HSPICE User Guide, RF Analysis

HSPICE User Guide, RF Analysis
HSPICE® User Guide: RF
Analysis
Version E-2010.12, December 2010
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ii
HSPICE® User Guide: RF Analysis
E-2010.12
Contents
1.
2.
3.
Inside This Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
xi
The HSPICE Documentation Set. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
xiii
Searching Across the HSPICE Documentation Set. . . . . . . . . . . . . . . . . . . . .
xiv
Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
xv
Customer Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
xv
HSPICE RF Features and Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
HSPICE RF Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
HSPICE RF Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
HSPICE and HSPICE RF Differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7
HSPICE/HSPICE RF Single Binary Integration . . . . . . . . . . . . . . . . . . . . . . . .
10
Use of Example Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
Getting Started. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
Running HSPICE RF Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
Netlist Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14
Parametric Analysis Extensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14
Generating Output Files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14
HSPICE RF Output File Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
Using Custom WaveViewTM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
HSPICE RF Tutorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19
Example 1: Using .LIN Analysis for a NMOS Low Noise Amplifier . . . . . . . . .
20
Example 2: Using HB Analysis for a Power Amplifier . . . . . . . . . . . . . . . . . . .
25
Example 3: Using HB Analysis for an Amplifier . . . . . . . . . . . . . . . . . . . . . . . .
29
Device Model Cards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
33
Example 4: Using HBOSC Analysis for a Colpitts Oscillator . . . . . . . . . . . . . .
37
Example 5: Using HBOSC Analysis for a CMOS GPS VCO . . . . . . . . . . . . . .
41
iii
Contents
Example 6: Using Multi-Tone HB and HBAC Analyses for a Mixer . . . . . . . . .
50
Two-tone HB Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
51
HBAC Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
52
Comparing Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
53
Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency Circuit and
a Ring Oscillator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
55
4.
iv
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
55
Shooting Newton Analysis Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
55
Driven Phase Frequency Detector Example . . . . . . . . . . . . . . . . . . . . . .
56
Ring Oscillator Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
62
Other Shooting Newton Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
66
RF Demonstration Input Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
67
Testbench Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
69
Values for Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
70
Ideal Transformer Format in HSPICE RF. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
70
DC Block and Choke Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
71
Multi-Terminal Linear Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
72
Scattering Parameter Data Element . . . . . . . . . . . . . . . . . . . . . . . . . . . .
72
Port Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
74
Port Element Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
75
Using the Port Element for Mixed-Mode Measurement . . . . . . . . . . . . . .
78
Steady-State Voltage and Current Sources . . . . . . . . . . . . . . . . . . . . . . . . . . .
79
I and V Element Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
79
Steady-State HB Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
83
Phase Differences Between HB and SIN Sources . . . . . . . . . . . . . . . . . . . . .
85
Behavioral Noise Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
86
Using Noise Analysis Results as Input Noise Sources . . . . . . . . . . . . . .
87
Power Supply Current and Voltage Noise Sources . . . . . . . . . . . . . . . . .
88
Function Approximations for Distributed Devices . . . . . . . . . . . . . . . . . . . . . .
90
Foster Pole-Residue Form for Transconductance or Gain . . . . . . . . . . . .
90
Advantages of Foster Form Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . .
90
G and E-element Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
91
Complex Signal Sources and Stimuli . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
92
Vector-Modulated RF (VMRF) Source . . . . . . . . . . . . . . . . . . . . . . . . . . .
92
Contents
5.
6.
Voltage and Current Source Elements. . . . . . . . . . . . . . . . . . . . . . . . . . .
94
SWEEPBLOCK in Sweep Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
100
Input Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
101
Using SWEEPBLOCK in a DC Parameter Sweep . . . . . . . . . . . . . . . . . .
101
Using in Parameter Sweeps in TRAN, AC, and HB Analyses . . . . . . . . .
102
Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
102
Clock Source with Random Jitter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
102
Syntax of SIN, COS, and Pulse Sources . . . . . . . . . . . . . . . . . . . . . . . . .
103
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
106
Steady-State Harmonic Balance Analysis . . . . . . . . . . . . . . . . . . . . . . . . . .
107
Harmonic Balance Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
108
Harmonic Balance Equations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
109
Features Supported . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
110
Input Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
110
HB Analysis Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
111
HB Analysis Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
113
Harmonic Balance Output Measurements . . . . . . . . . . . . . . . . . . . . . . . .
115
Output Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
116
Calculating Power Measurements After HB Analyses . . . . . . . . . . . . . . .
119
Calculations for Time-Domain Output . . . . . . . . . . . . . . . . . . . . . . . . . . .
122
Output Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
124
Using .MEASURE with .HB Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . .
124
HB Output Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
126
Errors and Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
128
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
130
Steady-State Shooting Newton Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . .
131
SN Steady-State Time Domain Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
131
SN Analysis Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
132
SN Analysis Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
134
Shooting Newton with Fourier Transform (.SNFT) . . . . . . . . . . . . . . . . . . . . . .
137
.SNFT Input Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
138
v
Contents
7.
8.
vi
Oscillator and Phase Noise Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
143
Harmonic Balance or Shooting Newton for Oscillator Analysis . . . . . . . . . . . .
144
Oscillator Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
144
Harmonic Balance Oscillator Analysis (.HBOSC) . . . . . . . . . . . . . . . . . . . . . .
144
Input Syntax for Harmonic Balance Oscillator Analysis . . . . . . . . . . . . . .
145
HB Simulation of Ring Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
150
HBOSC Analysis Using Transient Initialization . . . . . . . . . . . . . . . . . . . . . . . .
151
Additional .HBOSC Analysis Options. . . . . . . . . . . . . . . . . . . . . . . . . . . .
152
.HBOSC Output Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
153
Troubleshooting Convergence Problems . . . . . . . . . . . . . . . . . . . . . . . . .
153
Oscillator Analysis Using Shooting Newton (.SNOSC) . . . . . . . . . . . . . . . . . .
158
.SNOSC Output Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
160
Phase Noise Analysis (.PHASENOISE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
161
Phase Noise Analysis Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
161
Identifying Phase Noise Spurious Signals . . . . . . . . . . . . . . . . . . . . . . . .
163
PHASENOISE Input Syntax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
164
Phase Noise Algorithms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
167
PHASENOISE Output Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
168
Phase Noise Analysis Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
171
Measuring Phase Noise with .MEASURE PHASENOISE . . . . . . . . . . . .
172
Amplitude Modulation/Phase Modulation Separation . . . . . . . . . . . . . . .
173
Accumulated Jitter Measurement for Closed Loop PLL Analysis . . . . . . . . . .
177
Jitter Measurements from Phase Noise . . . . . . . . . . . . . . . . . . . . . . . . . .
178
Small-Signal Phase-Domain Noise Analysis (.ACPHASENOISE). . . . . . . . . .
184
AC Phase Noise Analysis Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
185
ACPHASENOISE Analysis .PRINT/.PROBE Syntax . . . . . . . . . . . . . . . .
185
Errors and Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
186
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
187
Large Signal Periodic AC, Transfer Function, and Noise Analyses . . . . .
189
Multitone Harmonic Balance AC Analysis (.HBAC) . . . . . . . . . . . . . . . . . . . . .
189
Prerequisites and Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
190
Input Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
191
Output Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
191
HBAC Output Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
193
Contents
Errors and Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
194
Shooting Newton AC Analysis (.SNAC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
195
Prerequisites and Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
196
Input Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
196
Output Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
197
SNAC Output Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
198
Errors and Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
199
SNAC Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
200
Phase Noise and Buffer Chains. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
200
Multitone Harmonic Balance Noise (.HBNOISE) . . . . . . . . . . . . . . . . . . . . . . .
201
Supported Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
202
Input Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
203
Output Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
205
Output Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
206
Measuring HBNOISE Analyses with .MEASURE . . . . . . . . . . . . . . . . . .
206
Errors and Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
209
HBNOISE Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
209
Shooting Newton Noise Analysis (.SNNOISE) . . . . . . . . . . . . . . . . . . . . . . . .
209
Supported Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
210
Input Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
211
Output Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
214
Output Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
215
Measuring SNNOISE Analyses with .MEASURE . . . . . . . . . . . . . . . . . .
215
SNNOISE Analysis Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
217
Periodic Time-Dependent Noise Analysis (.PTDNOISE) . . . . . . . . . . . . . . . . .
218
PTDNOISE Input Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
220
PTDNOISE Output Syntax and File Format. . . . . . . . . . . . . . . . . . . . . . .
222
Error Handling and Warnings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
224
Usage Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
224
Multitone Harmonic Balance Transfer Function Analysis (.HBXF). . . . . . . . . .
226
Supported Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
227
Input Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
227
Output Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
228
Output Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
229
Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
229
HBXF Test Listing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
230
Shooting Newton Transfer Function Analysis (.SNXF). . . . . . . . . . . . . . . . . . .
230
vii
Contents
Input Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
231
Output Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
232
Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
232
SNXF Test Listing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
233
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
234
Transient Noise Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
235
Overview of HSPICE/HSPICE RF Transient Noise Analysis . . . . . . . . . . . . . .
236
Techniques Available in HSPICE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
237
Modeling Frequency-Dependent Noise Sources . . . . . . . . . . . . . . . . . . . . . .
238
Monte Carlo Noise Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
239
Stochastic Differential Equation (SDE) Analysis . . . . . . . . . . . . . . . . . . . . . . .
241
Setting up a .TRANNOISE Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
243
Input Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
243
Monte Carlo Output Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
245
SDE Output Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
246
Monte Carlo Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
247
SDE Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
247
Jitter Measurements from .TRANNOISE Analysis Results . . . . . . . . . . . . . . .
247
Correlating Noise Results: .TRANNOISE (Monte Carlo) and .NOISE . . . . . . .
251
Error Handling, Error Recovery, Status Reporting . . . . . . . . . . . . . . . . . . . . . .
252
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
253
10. S-parameter Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
255
Frequency Translation S-Parameter (HBLIN) Extraction . . . . . . . . . . . . . . . . .
256
HB Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
258
9.
viii
231
Port Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
258
HBLIN Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
259
Output Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
262
Output Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
263
Large-Signal S-parameter (HBLSP) Analysis . . . . . . . . . . . . . . . . . . . . . . . . .
263
Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
264
Input Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
265
Output Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
267
Contents
Output Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
268
11. Envelope Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
269
Envelope Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
269
Envelope Analysis Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
270
Output Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
273
Envelope Output Data File Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
274
12. Post-Layout Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
277
Post-Layout Back-Annotation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
277
Standard Post-Layout Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
279
Selective Post-Layout Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
283
Additional Post-Layout Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
286
Selective Extraction Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
287
Overview of DSPF Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
288
Overview of SPEF Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
295
Linear Acceleration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
307
PACT Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
308
PI Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
309
Linear Acceleration Control Options Summary . . . . . . . . . . . . . . . . . . . .
309
13. Using HSPICE with HSPICE RF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
313
RF Numerical Integration Algorithm Control . . . . . . . . . . . . . . . . . . . . . . . . . .
313
RF Transient Analysis Accuracy Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
314
.OPTION SIM_ACCURACY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
314
Algorithm Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
315
RF Transient Analysis Output File Formats . . . . . . . . . . . . . . . . . . . . . . . . . . .
317
Tabulated Data Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
317
WDB Output Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
318
TR Output Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
318
NW Output Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
318
VCD Output Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
319
turboWave Output Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
319
Undertow Output Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
319
CSDF Output Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
320
Compressing Analog Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
320
ix
Contents
x
Eliminating Voltage Datapoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
320
Eliminating Current Datapoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
321
14. Advanced Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
323
Creating a Configuration File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
323
Inserting Comments in a .hspice File. . . . . . . . . . . . . . . . . . . . . . . . . . . .
326
Using Wildcards in HSPICE RF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
327
Limiting Output Data Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
327
SIM_POSTTOP Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
328
SIM_POSTSKIP Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
328
SIM_POSTAT Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
328
SIM_POSTDOWN Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
329
SIM_POSTSCOPE Option. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
329
Probing Subcircuit Currents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
329
Generating Measurement Output Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
331
Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
332
Optimizing AC, DC. and TRAN Analyses . . . . . . . . . . . . . . . . . . . . . . . . .
333
Optimizing HB Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
334
Optimizing HBOSC Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
335
Using CHECK Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
336
Setting Global Hi/Lo Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
336
Slew, Rise, and Fall Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
337
Edge Timing Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
338
Setup and Hold Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
338
IR Drop Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
340
POWER DC Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
340
Power DC Analysis Output Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
341
POWER Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
342
Setting Default Start and Stop Times. . . . . . . . . . . . . . . . . . . . . . . . . . . .
342
Controlling Power Analysis Waveform Dumps . . . . . . . . . . . . . . . . . . . . .
343
Detecting and Reporting Surge Currents. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
343
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
345
About This Guide
This manual contains detailed reference information, application examples, and
design flow descriptions that show how HSPICE RF features can be used for
RF circuit characterization. The manual supplements the HSPICE user
documentation by describing the additional features, built on top of the
standard HSPICE feature set, that support the design of RF and high-speed
circuits. Where necessary, the manual describes differences that might exist
between HSPICE RF and HSPICE.
Note:
This manual discusses only HSPICE RF features. For
information on other HSPICE applications, see the other
HSPICE manuals, listed in The HSPICE Documentation Set on
page xiii.
Inside This Manual
This manual contains the chapters described below. For access to the other
manuals in the HSPICE documentation set, see the next section, Searching
Across the HSPICE Documentation Set on page xiv.
Chapter
Description
Chapter 1, HSPICE RF
Features and Functionality
Introduces HSPICE RF features and functionality.
Chapter 2, Getting Started
Describes how to set up your environment, invoke HSPICE RF,
customize your simulation, and redirect input and output.
Chapter 3, HSPICE RF
Tutorial
Provides a quick-start tutorial for users new to HSPICE RF.
Chapter 4, Testbench
Elements
Discusses the syntax for the specialized elements supported
by HSPICE RF for high-frequency analysis and
characterization.
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xi
Inside This Manual
Chapter
Description
Chapter 5, Parameters and
Functions
Describes how to use parameters within HSPICE RF netlists.
Chapter 5, Steady-State
Harmonic Balance Analysis
Describes how to use harmonic balance analysis for
frequency-driven, steady-state analysis.
Chapter 6, Steady-State
Shooting Newton Analysis
Describes HSPICE RF steady-state time domain analysis
based on Shooting-Newton.
Chapter 7, Oscillator and
Phase Noise Analysis
Describes how to use HSPICE RF to perform oscillator and
phase noise analysis on autonomous (oscillator) circuits.
Chapter 8, Large Signal
Periodic AC, Transfer
Function, and Noise
Analyses
Describes how to use harmonic balance-based and Shooting
Newton AC analysis as well as nonlinear, steady-state noise
analysis and XF analysis.
Chapter 9, Transient Noise
Analysis
Describes the HSPICE and HSPICE RF solutions to perform
transient noise analysis and compute noise statistics and their
variation over time for circuits driven with non-periodic
waveforms.
Chapter 10, S-parameter
Analyses
Describes how to use periodically driven nonlinear circuit
analyses as well as noise parameter calculation.
Chapter 11, Envelope
Analysis
Describes how to use envelope simulation.
Chapter 12, Post-Layout
Analysis
Describes the post-layout flow, including post-layout backannotation, DSPF and SPEF files, linear acceleration, check
statements, and power analysis.
Chapter 13, Using HSPICE
with HSPICE RF
Describes how various analysis features differ in HSPICE RF
as compared to standard HSPICE.
Chapter 14, Advanced
Features
Describes how to invoke HSPICE RF and how to perform
advanced tasks, including redirecting input and output.
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HSPICE® User Guide: RF Analysis
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The HSPICE Documentation Set
The HSPICE Documentation Set
This manual is a part of the HSPICE documentation set, which includes the
following manuals:
Manual
Description
HSPICE User Guide:
Simulation and Analysis
Describes how to use HSPICE to simulate and
analyze your circuit designs, and includes simulation
applications. This is the main HSPICE user guide.
HSPICE User Guide:
Signal Integrity
Describes how to use HSPICE to maintain signal
integrity in your chip design.
HSPICE User Guide: RF
Analysis
Describes how to use special set of analysis and
design capabilities added to HSPICE to support RF
and high-speed circuit design.
HSPICE Reference
Manual: Commands and
Control Options
Provides reference information for HSPICE and
HSPICE RF commands and options.
HSPICE Reference
Manual: Elements and
Device Models
Describes standard models you can use when
simulating your circuit designs in HSPICE, including
passive devices, diodes, JFET and MESFET devices,
and BJT devices.
HSPICE Reference
Manual: MOSFET
Models
Describes available MOSFET models you can use
when simulating your circuit designs in HSPICE.
HSPICE Integration to
Cadence® Virtuoso®
Analog Design
Environment User Guide
Describes use of the HSPICE simulator integration to
the Cadence tool.
AMS Discovery
Simulation Interface
Guide for HSPICE
Describes use of the Simulation Interface with other
EDA tools for HSPICE.
AvanWaves User Guide
Describes the AvanWaves tool, which you can use to
display waveforms generated during HSPICE circuit
design simulation.
HSPICE® User Guide: RF Analysis
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xiii
Searching Across the HSPICE Documentation Set
Searching Across the HSPICE Documentation Set
You can access the PDF format documentation from your install directory for
the current release by entering -docs on the terminal command line when the
HSPICE tool is open.
Synopsys includes an index with your HSPICE documentation that lets you
search the entire HSPICE documentation set for a particular topic or keyword.
In a single operation, you can instantly generate a list of hits that are hyperlinked to the occurrences of your search term. For information on how to
perform searches across multiple PDF documents, see the HSPICE release
notes.
Note:
To use this feature, the HSPICE documentation files, the Index
directory, and the index.pdx file must reside in the same
directory. (This is the default installation for Synopsys
documentation.) Also, Adobe Acrobat must be invoked as a
standalone application rather than as a plug-in to your web
browser.
You can also invoke HSPICE and RF documentation in a browser-based help
system by entering-help on your terminal command line when the HSPICE
tool is open. This provides access to all the HSPICE manuals with the
exception of the AvanWaves User Guide which is available in PDF format only.
Known Limitations and Resolved STARs
You can find information about known problems and limitations and resolved
Synopsys Technical Action Requests (STARs) in the HSPICE Release Notes
shipped with this release. For updates, go to SolvNet.
To access the HSPICE Release Notes:
1. Go to https://solvnet.synopsys.com/ReleaseNotes. (If prompted, enter your
user name and password. If you do not have a Synopsys user name and
password, follow the instructions to register with SolvNet.)
2. Select Download Center> HSPICE> version number> Release Notes.
xiv
HSPICE® User Guide: RF Analysis
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Conventions
Conventions
The following typographical conventions are used in Synopsys HSPICE
documentation.
Convention
Description
Courier
Indicates command syntax.
Italic
Indicates a user-defined value, such as object_name.
Bold
Indicates user input—text you type verbatim—in syntax and
examples. Bold indicates a GUI element.
[ ]
Denotes optional parameters, such as:
write_file [-f filename]
...
Indicates that parameters can be repeated as many times as
necessary:
pin1 pin2 ... pinN
|
Indicates a choice among alternatives, such as
low | medium | high
+
Indicates a continuation of a command line.
/
Indicates levels of directory structure.
Edit > Copy
Indicates a path to a menu command, such as opening the
Edit menu and choosing Copy.
Control-c
Indicates a keyboard combination, such as holding down the
Control key and pressing c.
Customer Support
Customer support is available through SolvNet online customer support and
through contacting the Synopsys Technical Support Center.
HSPICE® User Guide: RF Analysis
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xv
Customer Support
Accessing SolvNet
SolvNet includes an electronic knowledge base of technical articles and
answers to frequently asked questions about Synopsys tools. SolvNet also
gives you access to a wide range of Synopsys online services, which include
downloading software, viewing Documentation on the Web, and entering a call
to the Support Center.
To access SolvNet:
1. Go to the SolvNet Web page at http://solvnet.synopsys.com.
2. If prompted, enter your user name and password. (If you do not have a
Synopsys user name and password, follow the instructions to register with
SolvNet.)
If you need help using SolvNet, click Help on the SolvNet menu bar.
The link to any recorded training is
https://solvnet.synopsys.com/trainingcenter/view.faces
Access recent release update training by going to
https://solvnet.synopsys.com/search/advanced_search.faces
Contacting the Synopsys Technical Support Center
If you have problems, questions, or suggestions, you can contact the Synopsys
Technical Support Center in the following ways:
■
Open a call to your local support center from the Web by going to
http://solvnet.synopsys.com/EnterACall (Synopsys user name and
password required).
■
Send an e-mail message to your local support center.
■
xvi
•
E-mail [email protected] from within North America.
•
Find other local support center e-mail addresses at
http://www.synopsys.com/support/support_ctr.
Telephone your local support center.
•
Call (800) 245-8005 from within the continental United States.
•
Call (650) 584-4200 from Canada.
•
Find other local support center telephone numbers at
http://www.synopsys.com/support/support_ctr.
HSPICE® User Guide: RF Analysis
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1
1
HSPICE RF Features and Functionality
Introduces HSPICE RF features and functionality.
HSPICE RF is a special set of analysis and design capabilities that support the
design of RF and high-speed circuits. This functionality, built on top of the
standard HSPICE feature set, is also useful for analog and signal integrity
applications. Although the HSPICE and HSPICE RF simulators share a
common set of device models and simulation capabilities, HSPICE RF includes
several modeling, simulation, and measurement additions that augment the
ultimate-accuracy analog circuit simulation capabilities of HSPICE.
Note:
This manual describes the additional features and capabilities of
HSPICE RF. Where necessary, the manual describes differences
between HSPICE RF and HSPICE. For information about
standard HSPICE device models, syntax, and simulation control,
you can refer to one of the other HSPICE manuals in the HSPICE
documentation set, listed in The HSPICE Documentation Set on
page xiii.
■
HSPICE RF Overview
■
HSPICE and HSPICE RF Differences
■
HSPICE/HSPICE RF Single Binary Integration
■
Use of Example Syntax
HSPICE® User Guide: RF Analysis
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1
Chapter 1: HSPICE RF Features and Functionality
HSPICE RF Overview
HSPICE RF Overview
HSPICE RF consists of:
■
The hspicerf simulation engine
■
The WaveView Analyzer tool
The hspicerf simulation engine contains extensions to HSPICE for RF design.
These extensions are in the form of new analysis commands and new
elements. The hspicerf simulation engine processes command and element
syntax for new RF simulation features but also accepts standard HSPICE
netlist files as input.
The WaveView Analyzer tool has been enhanced with special features for
reading and analyzing data created by the HSPICE RF simulation engine. For a
basic overview on how to use the WaveView Analyzer to view HSPICE RF
output, Using Custom WaveViewTM on page 16.
HSPICE RF can be launched with either the integrated executable (hspice) or
in standalone mode (hspicerf). Users can run RF features with one HSPICE
license and one HSPICE RF license or with two HSPICE licenses. The
following major RF analyses can be run by entering hspice on the commandline:
2
■
.ENV
■
.HB
■
.SN
■
.HBAC / .SNAC
■
.HBNOISE / .SNNOISE
■
.HBOSC /.SNOSC
■
.HBXF / .SNXF
■
.HBLIN
■
.PHASENOISE
■
.TRANNOISE
■
.STATEYE
HSPICE® User Guide: RF Analysis
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Chapter 1: HSPICE RF Features and Functionality
HSPICE RF Overview
HSPICE RF Features
This section briefly introduces the features of both the simulation engine and
the waveform display tool.
HSPICE RF supports most HSPICE capabilities, and also includes:
■
Steady-state frequency-domain analyses for linear and nonlinear circuits.
■
High-performance transient analysis for faster simulation of high-speed
digital and analog circuits.
■
Port-wise automated .AC analyses for S (scattering) parameters. The.LIN
command invokes extraction of noise and linear transfer parameters of a
multi-port linear network. Extracts the S parameter and generates the Nport model.
This command is used in conjunction with the .AC command to measure
multiport S, Y, and Z parameters, noise parameters, stability and gain
factors, and matching coefficients. Additionally, it is used with the Port
element, which identifies the network ports and their impedances. You can
also use mixed mode with .LIN.
■
The Port (P) element identifies ports used in LIN analysis (multiport S, Y, or
Z parameter and noise parameter extraction). A port element behaves as a
noiseless impedance or a voltage source in series with an impedance,
depending on the simulation being performed. Different impedances can be
specified for DC, transient, AC, HB, and HBAC analyses.
■
The S element describes a linear network using multi-port S, Y, or Z
parameters in the form of a frequency table. These parameters can come
from a .LIN simulation or from physical measurement. The standard
Touchstone (1.0/2.0) and CITIfile formats are supported in addition to a
proprietary HSPICE format.
■
The syntax of voltage and current sources as well as Port elements supports
the syntax for specifying power sources. In this case, the source value is
interpreted as a power value in Watts or dBm units, and the Port element is
implemented as a voltage source with a series impedance. The.HBLSP
command invokes periodically driven nonlinear circuit analyses for powerdependent S parameters.
■
Harmonic Balance (.HB) analysis using Direct and Krylov solvers. The.HB
command invokes the single and multitone Harmonic Balance algorithm for
periodic steady state analysis.
HSPICE® User Guide: RF Analysis
E-2010.12
3
Chapter 1: HSPICE RF Features and Functionality
HSPICE RF Overview
4
■
TRANFORHB element parameter to recognize V/I sources that include SIN
and PULSE transient descriptions as well as PWL and VMRF sources.
■
Harmonic balance-based periodic AC analysis. The .HBAC command
invokes periodic AC analysis for analyzing small-signal perturbations on
circuits operating in a large-signal periodic steady state.
■
Harmonic Balance-based Periodic Noise analysis (.HBNOISE) for noise
analysis of periodically modulated circuits, includes stationary,
cyclostationary, and frequency-dependent noise effects.
■
Autonomous Harmonic Balance analysis. The.HBOSC command invokes
the multitone, oscillator-capable Harmonic Balance algorithm for periodic
steady state analysis.
■
Perturbation analysis for Oscillator Phase Noise. The .HBAC command
invokes phase periodic AC noise for oscillators circuits operating in a largesignal steady-state.
■
Oscillator phase noise analysis, including both a nonlinear perturbation
method and a PAC method, and includes stationary, cyclostationary,
frequency-dependent, and correlated noise effects.
■
Frequency translation S-parameter and noise figure extraction with
the .HBLIN command.
■
Envelope analysis. The.ENV command: invokes standard envelope
simulation. The .ENVOSC command invokes envelope startup simulation.
The.ENVFFT command invokes envelope Fast Fourier Transform
simulation.
■
.OPTION HBTRANINIT, HBTRANPTS, and HBTRANSTEP for transient
analysis of ring oscillators.
■
Convolution for transient analysis of S-parameter data models (S-element).
■
Calculation of the transfer function from an arbitrary source and harmonic in
the circuit to a designated output with the .HBXF command.
■
Reading encrypted netlists.
■
.OPTION SIM_ACCURACY provides simplified accuracy control for all
simulations while .OPTION SIM_ORDER and SIM_TRAP improve transient
analysis simulation controls.
■
DSPF Flow for fast analysis using parasitic data from layout.
■
.OPTION SIM_LA provides linear acceleration for RC network reduction for
faster simulation.
HSPICE® User Guide: RF Analysis
E-2010.12
Chapter 1: HSPICE RF Features and Functionality
HSPICE RF Overview
■
Saving .PRINT simulation output to a separate file.
■
HERTZ variable for frequency-dependent equations.
■
IC=OFF in element statements, IC parameter (initial conditions).
■
Shooting Newton steady-state time domain analysis; the Shooting Newton
algorithm provides functionality to support the following commands: .SN,
.SNAC .SNFT, .SNNOISE, .SNOSC, and .SNXF.
■
Periodic Time-Dependent Noise Analysis (.PTDNOISE) calculates the
noise spectrum and the total noise at a point in time. Jitter in a digital
threshold circuit can then be determined from the total noise and the digital
signal slew rate.
■
PSF output using the PSF and ARTIST options to include HSPICE RF
analyses such as Harmonic Balance, Shooting Newton, and their
associated small-signal analyses within the CadenceTM design
environment.
■
With the 2008.09 release, the SX-WaveView waveform viewing tool is
capable of displaying the following HSPICE RF output file formats: .tr#, .sc#,
.hb#, .hr#, .ev#, .fe#, .jt#, .pn#, .ls#, .p2d#, .sw#, .ac#, .msn#, .sn#, and
Touchstone formatted files.
■
HSPICE RF supports ISUB syntax consistent with HSPICE with the
exception of wildcard support with the “?” sign. For example, isub(x1.a?)
is not supported by HSPICE RF.
■
HSPICE RF is consistent with HSPICE when handling .PRINT and .PROBE
statements containing wildcards.
■
When HSPICE RF is run in integrated executable (hspice) mode it is
supported by HSPICE Precision Parallel (-hpp) for multithread simulations
(but not in standalone mode).
■
When HSPICE RF is run in integrated executable mode (hspice), the case
sensitivity feature applies. (When run in standalone mode, HSPICE RF does
not support case sensitivity.)
HSPICE RF also adds the following measurement capabilities to HSPICE:
■
Small-signal scattering parameters.
■
Small-signal two-port noise parameters.
■
1dB compression point.
■
Intercept points (for example, IP2, IP3).
HSPICE® User Guide: RF Analysis
E-2010.12
5
Chapter 1: HSPICE RF Features and Functionality
HSPICE RF Overview
■
Mixer conversion gain and noise figure.
■
VCO output spectrum.
■
Oscillator phase noise.
■
Options simplify specifying levels of accuracy. As a result, HSPICE RF
provides effective simulation solutions for RF, high-speed, and PCB signal
integrity circuit challenges.
■
Verilog-A is supported for all HSPICE RF analyses, including:
■
■
6
•
HB
•
HBOSC
•
HBAC
•
HBNOISE
•
HBXF
•
PHASENOISE
•
SN
•
SNOSC
•
ENV
Standard restrictions for Verilog-A in periodic steady-state analysis are the
same as other RF simulators that use Verilog-A. For example:
•
Verilog-A modules that are time dependent cannot be used for HB or SN
unless the time dependence is periodic with a period that matches the
HB or SN setup.
•
Verilog-A modules with “internal states” are not guaranteed to work
correctly in HB or SN because the internal state cannot be tracked by
the engine, so HB or SN may think it is converged to a periodic steadystate even though the internal state may not be in periodic steady state.
•
Some event-driven constructs in Verilog-A may not be compatible with
HB.
For RF netlist input guidelines see Chapter 4, Input Netlist and Data Entry
in the HSPICE User Guide: Simulation and Analysis.
HSPICE® User Guide: RF Analysis
E-2010.12
Chapter 1: HSPICE RF Features and Functionality
HSPICE and HSPICE RF Differences
■
For information on RF use of Parameters and Functions see Chapter 10,
Parameters and Functions in the HSPICE User Guide: Simulation and
Analysis.
■
For information on use of Monte Carlo sweeps, see Chapter 20, Monte Carlo
- Traditional Flow and Statistical Analysis in the HSPICE User Guide:
Simulation and Analysis.
HSPICE and HSPICE RF Differences
The following tables give an overview of which features (Table 1) and device
models (Table 2 on page 10) in HSPICE are not supported in HSPICE RF.
Table 1
HSPICE Features Not in HSPICE RF
Feature
See
Read hspice.ini file.
HSPICE User Guide: Simulation and Analysis
Short names for internal sub-circuits, such as
10:M1.
HSPICE User Guide: Simulation and Analysis
.MODEL types: AMP and PLOT for graphs
HSPICE Reference Manual: Commands and
Control Options
Parameter definition (.PARAM) for Monte Carlo
statistical functions
HSPICE Reference Manual: Commands and
Control Options
.PLOT simulation output (obsolete for HSPICE
too which uses .PRINT/.PROBE)
HSPICE Reference Manual: Commands and
Control Options
.GRAPH simulation output (uses PLOT model
type) .GRAPH and .PLOT obsolete in
HSPICE.
HSPICE User Guide: Simulation and Analysis
HSPICE Reference Manual: Commands and
Control Options
.WIDTH, and many .OPTION COMMANDS
HSPICE User Guide: Simulation and Analysis
HSPICE Reference Manual: Commands and
Control Options
.OPTION ACCT
HSPICE User Guide: Simulation and Analysis
HSPICE Reference Manual: Commands and
Control Options
HSPICE® User Guide: RF Analysis
E-2010.12
7
Chapter 1: HSPICE RF Features and Functionality
HSPICE and HSPICE RF Differences
Table 1
HSPICE Features Not in HSPICE RF (Continued)
Feature
See
Element template output
HSPICE User Guide: Simulation and Analysis
Condition-controls: IF-ELSEIF-ELSE-ENDIF
structure is not currently supported in HSPICE
RF; however, you may be able to use the “a? b:
c” construct in expressions, which performs if/
then/else for expression evaluation
HSPICE User Guide: Simulation and Analysis
HSPICE Reference Manual: Commands and
Control Options
Group time delay parameters in AC analysis
output
HSPICE User Guide: Simulation and Analysis
.DISTO distortion analysis and associated
output commands
HSPICE User Guide: Simulation and Analysis
.SAVE and .LOAD
HSPICE Reference Manual: Commands and
Control Options
8
HSPICE® User Guide: RF Analysis
E-2010.12
Chapter 1: HSPICE RF Features and Functionality
HSPICE and HSPICE RF Differences
Table 1
HSPICE Features Not in HSPICE RF (Continued)
Feature
See
Options that activate unsupported features in
HSPICE RF:
FAST GSHDC GSHUNT
LIMPTS OFF RESMIN
TIMERES
All version options
HSPICE Reference Manual: Commands and
Control Options
Options ignored by HSPICE RF, because they
are not needed since they are replaced by
automated algorithms:
ABSH
ABSV ABSVAR
BELV
BKPSIZ CHGTOL
CONVERGE CSHDC CVTOL
DCFOR DCHOLD DCON
DCSTEP DI
DV
DVDT
FAST FS
FT
GMAX GRAMP
GSHDC GSHUNT ICSWEEP
IMAX
IMIN ITL3
ITL5
ITLPZ LIMPTS
LVLTIM MAXAMP MBYPASS
NEWTOL RELH RELI
RELQ
RELV RELVAR
TRTOL
All matrix options
All error options
Some Transient/AC input/output
(I/O) options. HSPICE RF does support POST
and PROBE options.
HSPICE Reference Manual: Commands and
Control Options
Sub-circuit cross-listing in a .pa file
HSPICE User Guide: Simulation and Analysis,
Chapter 3
-r command-line argument for a remote host
HSPICE User Guide: Simulation and Analysis
.OP supports node voltage for any time, but
supports element values only for t=0.
HSPICE Reference Manual: Commands and
Control Options
HSPICE® User Guide: RF Analysis
E-2010.12
9
Chapter 1: HSPICE RF Features and Functionality
HSPICE/HSPICE RF Single Binary Integration
Table 1
HSPICE Features Not in HSPICE RF (Continued)
Feature
See
Sensitivity analysis (.SENS)
HSPICE User Guide: Simulation and Analysis
HSPICE Reference Manual: Commands and
Control Options
DC mismatch analysis (.DCMATCH)
HSPICE User Guide: Simulation and Analysis
HSPICE Reference Manual: Commands and
Control Options
Table 2
Device Models Not in HSPICE RF
Model
See
B-element: IBIS buffer—
HSPICE User Guide: Signal Integrity
Bname n1 n2 [...] parameters
data-driven I element (current source)
HSPICE Reference Manual: Elements and Device
Models
data-driven V element (voltage source)
HSPICE Reference Manual: Elements and Device
Models
BJT LEVEL=10 (MODELLA)
HSPICE Reference Manual: Elements and Device
Models, Chapter 5
MOSFET Levels 4-8.
HSPICE Reference Manual: MOSFET Models
HSPICE/HSPICE RF Single Binary Integration
With the D-2010.03 release, users can run HSPICE and HSPICE RF features
from the unified HSPICE binary on all primary platforms. In addition, Synopsys
has unified HSPICE and HSPICE RF licensing. Users can now run RF features
with 1 HSPICE license and 1 HSPICE RF license or with 2 HSPICE licenses.
The command line entry is same as that of HSPICE:
hspice -i inputfile_name -o
10
HSPICE® User Guide: RF Analysis
E-2010.12
Chapter 1: HSPICE RF Features and Functionality
Use of Example Syntax
All major RF analyses listed here are supported in the HSPICE and HSPICE
RF Integration feature.
■
.ENV
■
.HB
■
.HBAC / .SNAC
■
.HBXF / SNXF
■
.HBLIN
■
.HBNOISE / .SNNOISE
■
.PHASENOISE
■
.TRANNOISE
■
.STATEYE
■
and more...
In addition, the other triggers for calling the RF engine include:
■
vmrf sources
■
cos sources
■
power sources
■
spur G and E control sources
■
sweepblock
■
source with “noisefile”
■
L-element with transformer_nt
■
G-element node1 node2 node3 node4 noise
■
vmrf sources
Use of Example Syntax
To copy and paste proven syntax use the demonstration files shipped with your
installation of HSPICE (see Listing of Demonstration Input Files). Attempting to
copy and paste from the book or help documentation may present unexpected
results, as text used in formatting may include hidden characters, white space,
etc. for visual clarity only.
HSPICE® User Guide: RF Analysis
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11
Chapter 1: HSPICE RF Features and Functionality
Use of Example Syntax
12
HSPICE® User Guide: RF Analysis
E-2010.12
2
Getting Started
2
Describes how to set up your environment, invoke HSPICE RF, customize your
simulation, redirect input and output, and use the Custom WaveViewTM tool.
Before you run HSPICE RF, you need to set up several environment variables.
You can also create a configuration file to customize your simulation run.
HSPICE RF accepts a netlist file from standard input and delivers the ASCII
text simulation results to HTML or to standard output. Error and warning
messages are forwarded to standard error output.
These topics are covered in the following sections:
■
Running HSPICE RF Simulations
■
Netlist Overview
■
Parametric Analysis Extensions
■
Generating Output Files
■
Using Custom WaveViewTM
Running HSPICE RF Simulations
Use the following syntax to invoke HSPICE RF:
hspicerf [-a] inputfile [outputfile] [-n] [-h] [-v]
For a description of the hspicerf command syntax and arguments, see
section hspicerf in the HSPICE Reference Manual: Commands and Control
Options.
HSPICE® User Guide: RF Analysis
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13
Chapter 2: Getting Started
Netlist Overview
Netlist Overview
The circuit description syntax for HSPICE RF is compatible with the SPICE and
HSPICE input netlist format. For a description of an input netlist file and
methods of entering data, see Chapter 4, Input Netlist and Data Entry in the
HSPICE User Guide: Simulation and Analysis.
Parametric Analysis Extensions
All major HSPICE RF analyses (.TRAN, .AC, .DC, and .HB) support the
following parameter sweeps with the same syntax as standard HSPICE:
■
LIN
■
DEC
■
OCT
■
DATA
■
POI
You can also use the MONTE keyword for a Monte Carlo analysis or the
OPTIMIZE keyword for optimization.
Generating Output Files
HSPICE RF generates a table of simulation outputs.
■
If the output is text (the default), the text is put into a .lis file.
■
If you specify .OPTION POST, then HSPICE RF generates simulation
output in a format suitable for a waveform display tool.
■
The default output format for transient analysis in HSPICE RF is the same
as in HSPICE: the .tr0 file format. For additional information, see Standard
Output Files in the HSPICE User Guide: Simulation and Analysis.
The Synopsys interactive waveform display tool, Custom WaveView, can
display both the text simulation results and binary output within the X-window
environment.
14
HSPICE® User Guide: RF Analysis
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Chapter 2: Getting Started
Generating Output Files
All output functions (.PRINT, .PROBE, .MEASURE, and so on) can use power
output variables in the form p(devicename), just as in HSPICE. You can also
use the “power” keyword.
Larger output files from multi-million transistor simulations might not be
readable by some waveform viewers. Options are available that enable you to
limit the output file size. See Limiting Output Data Size on page 327 for more
information.
HSPICE RF Output File Types
Table 3 shows the output file extensions that HSPICE RF analyses produce.
The base file name of each output file is the same as the input netlist file’s base
name. The # at the end of each file extension represents the .ALTER run from
which the file came.
In general, text output from .PRINT commands is intended to be read by users,
while binary output from .PROBE or .OPTION POST is intended to be read by
the Custom WaveView tool.
Table 3
HSPICE RF Output File Types
Command
Text Output
Output for CosmosScope
AC analysis (.AC)
.printac#
.ac#
AC noise analysis (.NOISE) .printac#
.ac#
DC sweep (.DC)
.printsw#
.sw#
Envelope analysis (.ENV)
.printev#
.ev#
Envelope FFT (.ENVFFT)
(none)
.fe#
Harmonic Balance (.HB)
.printhb#
.hb#
Harmonic Balance AC
(.HBAC)
.printhb#
.hb#
.HBLIN analysis
.PRINT output: .printhl#
S-param output: .SnP
.PROBE output: .hl#
S-paramr output: .SnP
.HBLSP large-signal
.PRINT output: .printls#
S-param output: .p2d#
.PROBE output: .ls#
S-param output: .p2d#
HSPICE® User Guide: RF Analysis
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15
Chapter 2: Getting Started
Using Custom WaveViewTM
Table 3
HSPICE RF Output File Types
Command
Text Output
Output for CosmosScope
.HBLSP small-signal
.PRINT output: .printss#
S/noise output: .S2P#
.PROBE output: .ss#
S/noise output: .S2P#
HBAC noise (.HBNOISE)
.printsnpn#
.pn#
Harmonic Balance OSC
(.HBOSC)
.printhb#
.hb#
Harmonic Balance TRAN
(.HBTRAN)
.printhr#
.hr#
Transfer Functions (.HBXF)
.printxf#
.xf#
Oscillator startup
(.ENVOSC)
.printev#
.ev#
.LIN analysis
.PRINT output: .printac#;
S/noise output: .sc#, .SnP,
.citi#
.PROBE output: .ac#;
S/noise output: .sc#,
.SnP, .citi#
Phase Noise
(.PHASENOISE)
.printsnpn#
.pn#
.SN analysis
.printsn#
.sn#
Transient analysis (.TRAN)
.printtr#
.tr#
Using Custom WaveViewTM
The Custom WaveView has been enhanced to support viewing and processing
of HSPICE RF output files. This section presents a basic overview of how to
use the WaveView to view HSPICE RF output.
16
■
To start the Custom WaveView tool, type wv on the UNIX/Linux command
line.
■
Choose File > Import Waveform File (or press CTRL-O) to open the Open
Waveform Files dialog box. Use the File Filters to limit the file names to
Waveform Files. A list of the HSPICE RF file types can be found in Table 3
HSPICE® User Guide: RF Analysis
E-2010.12
Chapter 2: Getting Started
Using Custom WaveViewTM
on page 15. When you open a file, its contents appear in the file browser.
The file browser lists all open plot files. If you click on the '+' near a waveform
file name, the hierarchy of the waveform file is shown and clicking on top
level or any hierarchy level will display the contents of the waveform file to
be shown in the signal browser. To plot one of the signals listed here in the
waveview, you can either double-click the signal label or select, drag, and
drop the signal label to the waveview.
■
To create a panel, use the Panel > New menu and select the panel type, XY, Smith Chart, or Polar Plot. You can also use the panel icon in the toolbar
to create new panels.
■
To create a new chart, use the File > New menu. Select either XY Graph,
Smith Chart, or Polar Chart. You can also use the first three icons in the
toolbar to create new chart windows.
■
Use the waveview tool bar to change how signals look, delete signals, group
or ungroup signals.
■
Right click on a frequency domain signal name and use the To Time Domain
command to convert the histogram waveform (for example, from an .hb0
file) to a time domain waveform.
■
Configure the axis scaling and grid by right-clicking a horizontal or vertical
axis and selecting the desired scale or grid from the context sensitive menu.
■
Zoom in and out, using the zoom icons on the waveview tool bar, or use the
mouse cursor to select an area directly on the waveview.
■
Dynamic meters can be used to see the signal's precise value at different
points. From the menu, select Tools > Dynamic Meter or use the Dynamic
Meter icon in the tool bar. Select and configure the desired Dynamic Meter.
The meter can then be moved to the desired location on the selected signal.
■
To use the measurement tools, choose Tools > Measurement. Three RF
measurements have been added under the All tab of the Measurement Tool
window:
•
1db compression point (P1dB).
•
2nd order intercept point (IP2).
•
3rd order intercept point and spurious free dynamic range (IP3/SFDR).
HSPICE® User Guide: RF Analysis
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17
Chapter 2: Getting Started
Using Custom WaveViewTM
18
HSPICE® User Guide: RF Analysis
E-2010.12
3
3
HSPICE RF Tutorial
Provides a quick-start tutorial for users new to HSPICE RF.
This tutorial assumes you are familiar with HSPICE and general HSPICE
syntax, but new to RF analysis features. The most basic RF analysis features
are presented here, using simple examples. The end of this chapter contains a
listing of HSPICE RF demonstration files available for your use when you have
access to the HSPICE RF installation directory.
This tutorial covers the following examples:
■
Example 1: Using .LIN Analysis for a NMOS Low Noise Amplifier
■
Example 2: Using HB Analysis for a Power Amplifier
■
Example 3: Using HB Analysis for an Amplifier
■
Example 4: Using HBOSC Analysis for a Colpitts Oscillator
■
Example 5: Using HBOSC Analysis for a CMOS GPS VCO
■
Example 6: Using Multi-Tone HB and HBAC Analyses for a Mixer
■
Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency
Circuit and a Ring Oscillator
HSPICE® User Guide: RF Analysis
E-2010.12
19
Chapter 3: HSPICE RF Tutorial
Example 1: Using .LIN Analysis for a NMOS Low Noise Amplifier
In addition, there is a section listing all RF examples, including those not
covered in these tutorial examples:
■
RF Demonstration Input Files
Example 1: Using .LIN Analysis for a NMOS Low Noise
Amplifier
The .LIN command simplifies the calculation of linear multi-port transfer
parameters and noise parameters. In the LIN analysis, Port (P) elements are
used to specify port numbers and their characteristic impedances. The analysis
automatically computes the frequency-dependent complex transfer coefficients
between ports. The result is a convenient means to get scattering parameters,
noise parameters, stability parameters, and gain coefficients. The .LIN
command renders obsolete the .NET command. By default, the output from
the .LIN command is saved in the *.sc0 file format that can, in turn, be
referenced as a model file for the S-parameter element.
To set up a linear transfer parameter analysis, the HSPICE input netlist must
contain the following:
■
Use the .AC command to activate small-signal AC analysis, and to specify
a frequency sweep. Also, use the .AC command to specify any other
parameter sweeps of interest.
■
Use the .LIN command with the .AC command to activate small-signal
linear transfer analysis. The .AC command specifies the base frequency
sweep for the LIN analysis. The LIN analysis automatically performs multiple
AC and NOISE analyses as needed to compute all complex signal transfer
parameters.
■
The necessary number of port (P) elements, numbered sequentially
beginning with one to define the terminals of the multi-port network. For
example, a two-port circuit must contain two port elements with one listed
as port=1 and the other as port=2. The port elements define the ordering for
the output quantities from the .LIN command (for example, the terminals
for port=1 are used for S11, Y11, and Z11 measurements).
Much of the LIN analysis is automated so the HSPICE input netlist often does
not require the following:
20
HSPICE® User Guide: RF Analysis
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Chapter 3: HSPICE RF Tutorial
Example 1: Using .LIN Analysis for a NMOS Low Noise Amplifier
■
AC signal sources. The .LIN command computes transfer parameters
between the ports with no additional AC sources needed.
■
DC sources. You can analyze a purely passive circuit without adding
sources of any kind.
The following tutorial example shows how to set up a LIN analysis for an NMOS
low noise amplifier circuit. This netlist is shipped with the HSPICE RF
distribution as gsmlna.sp and is available in the directory:
$installdir/demo/hspicerf/examples.
HSPICE® User Guide: RF Analysis
E-2010.12
21
Chapter 3: HSPICE RF Tutorial
Example 1: Using .LIN Analysis for a NMOS Low Noise Amplifier
Figure 1
22
Schematic Showing Instantiation for Low Noise Amplifier
HSPICE® User Guide: RF Analysis
E-2010.12
Chapter 3: HSPICE RF Tutorial
Example 1: Using .LIN Analysis for a NMOS Low Noise Amplifier
** NMOS 0.25um Cascode LNA for GSM applications
** setup for s-parameter and noise parameter measurements
**
.temp 27
.options post
.param
Vdd=2.3
.global gnd
**
** Cascode LNA tuned for operation near 1 GHz
**
M1 _n4 _n3 _n5 _n5 CMOSN l=0.25u w=7.5u
+
as=15p ad=15p ps=19u pd=19u m=80
M2 _n6 _n1 _n4 _n4 CMOSN l=0.25u w=7.5u
+
as=15p ad=15p ps=19u pd=19u m=80
M3 rfo _n6 gnd gnd CMOSN l=0.25u w=7.5u
+
as=15p ad=15p ps=19u pd=19u m=40
r1 _vdd _n6 400
l1 _n5 gnd l=0.9nH
l2 rfin _n3 l=13nH
vvb _n1 gnd
dc=1.19 $ bias for common base device
vvdd _vdd gnd dc=Vdd
rfb rfo _n6 120 $ feedback
**
** 50 Ohm input port (incl. bias), 255 Ohm output port.
**
P1 rfin gnd port=1 z0=50 dc = 0.595 $ input port includes DC bias
P2 rfo _vdd port=2 z0=255 $ port doubles as pull-up resistor
**
** Measure s-parameters and noise parameters
**
.AC DEC 50 100MEG 5G
.LIN noisecalc=1 sparcalc=1 format=touchstone
.PRINT S11(DB) S21(DB) S12(DB) S22(DB) NFMIN
**
.PROBE NFMIN G_AS K_STABILITY_FACTOR
** Approximate parameters for TSMC 0.25 Process (MOSIS run T17B)
**
.MODEL CMOSN NMOS (
LEVEL
= 49
3.1
TNOM
= 27
TOX
= 5.8E-9
+XJ
= 1E-7
NCH
= 2.3549E17
VTH0
= 0.3819327
+K1
= 0.477867
K2
= 2.422759E-3
K3
= 1E-3
+K3B
= 2.1606637
W0
= 1E-7
NLX
= 1.57986E-7
+DVT0W
= 0
DVT1W
= 0
DVT2W
= 0
+DVT0
= 0.5334651
DVT1
= 0.7186877
DVT2
= -0.5
+U0
= 289.1720829
UA
= -1.300598E-9
UB
= 2.3082E-18
HSPICE® User Guide: RF Analysis
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23
Chapter 3: HSPICE RF Tutorial
Example 1: Using .LIN Analysis for a NMOS Low Noise Amplifier
+UC
+AGS
+KETA
+RDSW
+WR
+XL
+DWB
+CIT
+CDSCB
+DSUB
+PDIBLC2
+PSCBE1
+DELTA
+PRT
+KT1L
+UB1
+WL
+WWN
+LLN
+LWL
+CGDO
+CJ
+CJSW
+CJSWG
+CF
+PK2
*
.END
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
2.841618E-11
0.2874763
-2.395348E-3
178.7751373
1
3E-8
4.613042E-9
0
0
0.0463218
4.422611E-3
7.982649E10
0.01
0
0
-7.61E-18
0
1
1
0
5.62E-10
1.641005E-3
4.179682E-10
3.29E-10
0
2.650965E-3
VSAT
B0
A1
PRWG
WINT
XW
VOFF
CDSC
ETA0
PCLM
PDIBLCB
PSCBE2
RSH
UTE
KT2
UC1
WLN
WWL
LW
CAPMOD
CGSO
PB
PBSW
PBSWG
PVTH0
WKETA
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
1.482651E5
-1.833193E-8
0
0.3774172
0
-4E-8
-0.0981658
2.4E-4
5.128492E-3
1.91946
-0.1
5.200359E-10
3.7
-1.5
0.022
-5.6E-11
1
0
0
2
5.62E-10
0.99
0.99
0.99
-8.385037E-3
7.293869E-3
A0
B1
A2
PRWB
LINT
DWG
NFACTOR
CDSCD
ETAB
PDIBLC1
DROUT
PVAG
MOBMOD
KT1
UA1
AT
WW
LL
LWN
XPART
CGBO
MJ
MJSW
MJSWG
PRDSW
LKETA
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
1.6856991
-1E-7
0.4177975
-0.2
1.88839E-8
-1.2139E-8
1.2032376
0
6.18609E-4
1
0.9817908
9.31443E-3
1
-0.11
4.31E-9
3.3E4
0
0
1
0.5
1E-12
0.4453094
0.3413857
0.3413857
-10
-6.070E-3)
A LIN analysis also includes the following:
■
.LIN command:
.LIN noisecalc=1 sparcalc=1 format=touchstone
This invokes a LIN analysis and activates noise calculations and Sparameter output files in TouchStone format.
■
Two port elements:
P1 rfin gnd port=1 z0=50 dc=0.595
Specifies that an input port is assumed between terminals rfin and
ground, that it is has a 50 ohm termination, and it has a built-in DC bias of
0.595 V. The output (second) port is:
P2 rfo _vdd port=2 z0=255
24
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Chapter 3: HSPICE RF Tutorial
Example 2: Using HB Analysis for a Power Amplifier
This syntax specifies that the output port is between terminals rfo and vdd,
and is being used as a pull up resistor with impedance of 255 ohms.
■
A .PRINT command for plotting the output S parameters in dB and the
noise figure minimum.
To run this netlist, type the following command:
hspicerf gsmlna.sp
This produces three output files, named gsmlna.ac0, gsmlna.s2p, and
gsmlna.printac0, containing the AC analysis results, S-parameter and noise
parameter results, and the requested PRINT data.
To view the output:
1. Type wv at the prompt to invoke Custom WaveView.
2. Use File > Import Waveform File and select the gmslna.s2p file from the
Open: Waveform Files dialog box.
3. Use Panel > New > Smith Chart or use the tool bar to open a blank Smith
chart in the waveform.
4. Select the S(1,1) and S(2,2) signals in the signal browser. Drag and drop the
selected signals in the Smith Chart.
5. Use Panel > New > Polar Plot or the use the tool bar to open a blank Polar
chart.
6. Select the S(2,1) signal in the signal browser. Drag and drop the signal in
the Polar chart to plot the complex gain of the LNA.
7. Use File > Import Waveform File and select the gmslna.ac0 file from the
Open: Waveform Files dialog box.
8. Use Waveview > New to open a new waveform.
9. Select the g_as (associated gain), k_stability_factor (Rollet stability factor)
and nfmin (the noise figure minimum) signals in the signal browser. Drag
and drop the selected signals in the new waveform.
Example 2: Using HB Analysis for a Power Amplifier
The .HB command computes periodic steady-state solutions of circuits. This
analysis uses the Harmonic Balance (HB) technique for computing such
solutions in the frequency domain. The circuit can be driven by a voltage,
HSPICE® User Guide: RF Analysis
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25
Chapter 3: HSPICE RF Tutorial
Example 2: Using HB Analysis for a Power Amplifier
power, or current source, or it may be an autonomous oscillator. The HB
algorithm represents the circuit’s voltage and current waveforms as a Fourier
series, that is, a series of sinusoidal waveforms.
To set up a periodic steady-state analysis, the HSPICE input netlist must
contain:
■
A .HB command to activate the analysis. The .HB command specifies the
base frequency (or frequencies, also called tones) for the analysis, and the
number of harmonics to use for each tone. The .HB command can specify
base tones so that the circuit solution is represented as a multi-dimensional
Fourier series. The number of terms in the series are determined by the
number of harmonics; more harmonics result in higher accuracy, but also
longer simulation times and higher memory usage.
■
One or more signal sources for driving the circuit in HB analysis, if the circuit
is driven. In the case of autonomous oscillator analysis, no signal source is
required. Signal sources are specified using the HB keyword on the voltage
or current source syntax. Power sources are specified by setting the power
switch on voltage/current sources to 1; in this case, the source value is
treated as a power value in Watts instead of a voltage or current.
Optionally, the netlist can also contain a set of control option for optimizing HB
analysis performance.
The following example shows how to set up a Harmonic Balance analysis on an
NMOS Class C Power Amplifier. The example compares transient analysis
results to Harmonic Balance results.
The following netlist performs both a transient and a Harmonic Balance
analysis of the amplifier driven by a sinusoidal input waveform. The accurate
option is set to ensure sufficient number of time points for comparison with HB.
This example is included with the HSPICE RF distribution as pa.sp and is
available in directory $installdir/demo/hspicerf/examples.
26
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Chapter 3: HSPICE RF Tutorial
Example 2: Using HB Analysis for a Power Amplifier
Figure 2
Power Amplifier
.options POST accurate
.param f0=950e6 PI=3.1415926 Ld=2e-9 Rload=5 Vin=3.0
.param Lin=0.1n Vdd=2 Cd='1.0/(4*PI*PI*f0*f0*Ld)'
M1 drain gt 0 0 CMOSN L=0.35u W=50u AS=100p AD=100p
PS=104u PD=104u M=80
Ls in gt
Lin $ gate tuning
Ld drain vdd Ld $ drain tuning
Cd drain 0
Cd
Cb drain out
INFINITY $ DC block
Rload out
0
Rload
Vdd vdd 0
DC
Vdd
Vrf1 in
0
DC 'Vin/2.0'
+ SIN ('Vin/2' 'Vin/2' 'f0' 0 0 90)
+ HB 'Vin/2' 0.0 1 1
.hb tones=f0 nharms=10
.tran 10p 10n
.probe hb p(Rload)
.probe tran p(Rload)
.include cmos49_model.inc
.end
An HB analysis uses the following:
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Chapter 3: HSPICE RF Tutorial
Example 2: Using HB Analysis for a Power Amplifier
■
An .HB command:
.hb tones=f0 nharms=10
For a single tone analysis with base frequency 950 mHz and 10 harmonics.
■
The HB source in Vrf1:
HB ‘Vin/2’ 0.0 1 1.
This creates a sinusoidal waveform matching the transient analysis one.
The amplitude is Vin/2=1.5 V, and it applies to the first harmonic of the first
tone, 950 MHz.
■
A .PROBE command for plotting the output power:
.probe hb p(Rload)
To run this netlist, type the following command:
hspicerf pa.sp
This produces two output files named pa.tr0 and pa.hb0, containing the
transient and HB output, respectively. To view and compare the output:
1. Type wv at the prompt to invoke Custom WaveView.
2. Use File > Import Waveform File and select the pa.tr0 and pa.hb0 files from
the Open: Waveform Files dialog box.
3. Select the v(out) signal from the pa.hb0 in the signal browser. Double-click
on the signal name or drag and drop the signal in the waveform. The
histogram shows lines at 950MHz, and multiples thereof, up to 9.5GHz.
4. In the waveform, right click in the name area of the panel containing the
signal v(out), left-click on the waveform label for v(out) from the pa.hb0 file.
From the Panel menu, choose Signal 'v(out)' > To Time-Domain.
5. In the Convert to Time Domain window, change the X-End(sec) value to
10n.
6. Click OK to accept the settings.
7. The new waveform shows a new time domain waveform named IFT.0|v(out).
8. Select the v(out) signal from the pa.tr0 in the signal browser. Drag and drop
the signal in the waveform containing IFT.0|v(out). This should overlay the
IFT.0|v(out) and v(out) signals on the same waveform. Zoom into the
transitions to see the slight differences between the waveforms.
28
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Chapter 3: HSPICE RF Tutorial
Example 3: Using HB Analysis for an Amplifier
Example 3: Using HB Analysis for an Amplifier
This example takes the LNA circuit of Example 1 and performs a simulation
using two closely spaced steady-state tones to study the compression and third
order distortion properties of the amplifier. The example file gsmlnaIP3.sp is
located at: /$installdir/demo/hspicerf/examples/
See Figure 1 on page 22 for the schematic view.
HSPICE® User Guide: RF Analysis
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Chapter 3: HSPICE RF Tutorial
Example 3: Using HB Analysis for an Amplifier
** NMOS 0.25um Cascode LNA for GSM applications
** Test bench setup for two-tone power sweep in dBm
** to extract IP3.
.temp 27
.options post=2
.param
Vdd=2.3
.global gnd
.param Pin:dBm=-30.0
.param Pin=Pin:dBm
.param Pin:W='1.0e-3*pwr(10.0,Pin/10.0)' $ Change to Watts for
sources
**
** Cascode LNA tuned for operation near 1 GHz
**
M1 _n4 _n3 _n5 _n5 CMOSN l=0.25u w=7.5u as=15p ad=15p ps=19u
pd=19u m=80
M2 _n6 _n1 _n4 _n4 CMOSN l=0.25u w=7.5u as=15p ad=15p ps=19u
pd=19u m=80
M3 rfo _n6 gnd gnd CMOSN l=0.25u w=7.5u as=15p ad=15p ps=19u
pd=19u m=40
r1 _vdd _n6 400
l1 _n5 gnd l=0.9nH
l2 rfin _n3 l=13nH $ 0.65n
vvb _n1 gnd
dc=1.19 $ bias for common base device
vinb rfinb gnd dc=0.595
lchk rfin rfinb INFINITY $ Choke
cblk rfin rfind INFINITY $ DC block
vvdd _vdd gnd dc=Vdd
rfb rfo _n6 120
$ feedback
**
** Two-tone input source (DC blocked at this point)
**
Vin rfind gnd dc=0 power=1 z0=50 $ 50 Ohm src
+ HB Pin:W 0 1 1 $ tone 1
+ HB Pin:W 0 1 2 $ tone 2
Rload rfo _vdd R=255
**
** HB test bench to measure IP3 and IP2
**
.HB tones=900MEG,910MEG nharms=11 11 intmodmax=7
+ SWEEP Pin:dBm -50.0 0.0 2.0
.print HB P(Rload) P(Rload)[1,0] P(Rload)[2,0] P(Rload)[2,-1]
.probe HB P(Rload) P(Rload)[1,0] P(Rload)[2,0] P(Rload)[2,-1]
**
** Approximate parameters for MOSIS 0.25um process (run T17B)
**
.MODEL CMOSN NMOS(
LEVEL
= 49
+VERSION
= 3.1
TNOM
= 27
TOX
= 5.8E-9
+XJ
= 1E-7
NCH
= 2.3549E17
VTH0
= 0.3819327
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Chapter 3: HSPICE RF Tutorial
Example 3: Using HB Analysis for an Amplifier
+K1
= 0.477867
K2
= 2.422759E-3
K3
= 1E-3
+K3B
= 2.1606637
W0
= 1E-7
NLX
= 1.579864E-7
+DVT0W
= 0
DVT1W
= 0
DVT2W
= 0
+DVT0
= 0.5334651
DVT1
= 0.7186877
DVT2
= -0.5
+U0
= 289.1720829
UA
= -1.300598E-9
UB
= 2.308197E-18
+UC
= 2.841618E-11
VSAT
= 1.482651E5
A0
= 1.6856991
+AGS
= 0.2874763
B0
= -1.833193E-8
B1
= -1E-7
+KETA
= -2.395348E-3
A1
= 0
A2
= 0.4177975
+RDSW
= 178.7751373
PRWG
= 0.3774172
PRWB
= -0.2
+WR
= 1
WINT
= 0
LINT
= 1.888394E-8
+XL
= 3E-8
XW
= -4E-8
DWG
= -1.213938E-8
+DWB
= 4.613042E-9
VOFF
= -0.0981658 NFACTOR = 1.2032376
+CIT
= 0
CDSC
= 2.4E-4
CDSCD
= 0
+CDSCB
= 0
ETA0
= 5.128492E-3
ETAB
= 6.18609E-4
+DSUB
= 0.0463218
PCLM
= 1.91946
PDIBLC1
= 1
+PDIBLC2 = 4.422611E-3
PDIBLCB
= -0.1
DROUT
= 0.9817908
+PSCBE1 = 7.982649E10 PSCBE2 = 5.200359E-10 PVAG = 9.314435E-3
+DELTA
= 0.01
RSH
= 3.7
MOBMOD
= 1
+PRT
= 0
UTE
= -1.5
KT1
= -0.11
+KT1L
= 0
KT2
= 0.022
UA1
= 4.31E-9
+UB1
= -7.61E-18
UC1
= -5.6E-11
AT
= 3.3E4
+WL
= 0
WLN
= 1
WW
= 0
+WWN
= 1
WWL
= 0
LL
= 0
+LLN
= 1
LW
= 0
LWN
= 1
+LWL
= 0
CAPMOD
= 2
XPART
= 0.5
+CGDO
= 5.62E-10
CGSO
= 5.62E-10
CGBO
= 1E-12
+CJ
= 1.641005E-3
PB
= 0.99
MJ
= 0.4453094
+CJSW
= 4.179682E-10
PBSW
= 0.99
MJSW
= 0.3413857
+CJSWG
= 3.29E-10
PBSWG
= 0.99
MJSWG
= 0.3413857
+CF
= 0
PVTH0
= -8.385037E-3
PRDSW
= -10
+PK2 = 2.650965E-3 WKETA= 7.293869E-3
LKETA = -6.070221E-3 )
*
.END
First, notice that we have defined variables that allow power to be swept in dBm
units.
.param Pin:dBm=-30.0
.param Pin=Pin:dBm
.param Pin:W='1.0e-3*pwr(10.0,Pin/10.0)'
References to sources must use SI units in with the previous equation to
convert from dBm to Watts. The colon (:) is used as a labeling convenience.
Second, a voltage source element is used as a two-tone power source by
setting the power flag and a source impedance of 50 ohms is specified. The HB
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Chapter 3: HSPICE RF Tutorial
Example 3: Using HB Analysis for an Amplifier
keyword is used to identify the amplitude (interpreted in Watts with the power
flag set), phase, harmonic index, and tone index for each tone.
Vin rfind gnd dc=0 power=1 z0=50 $ 50 Ohm src
+ HB Pin:W 0 1 1
$ tone 1
+ HB Pin:W 0 1 2
$ tone 2
Third, the .HB command designates the frequencies of the two tones and
establishes the power sweep using the dBm power variable. The intmodmax
parameter has been set to 7 to include intermodulation harmonic content up to
7th order effects.
.HB tones=900MEG,910MEG nharms=11 intmodmax=7
+ SWEEP Pin:dBm -50.0 0.0 2.0
Last, the HSPICE RF ability to specify specific harmonic terms is used in
the .PRINT and .PROBE statements to pull out the signals of particular
interest. Notice the three different formats:
.PRINT HB P(Rload)
This reference dumps a complete spectrum in RMS Watts for the power across
resistor Rload.
.PRINT HB P(Rload)[1,0]
This reference selectively dumps the power in resistor Rload at the first
harmonic of the 1st tone.
.PRINT HB P(Rload)[2,-1]
This reference selectively dumps the power in resistor Rload at the 3rd
intermodulation product frequency (890 MHz).
To run this simulation, type the following at the command line:
hspicerf gsmlnaIP3.sp
Viewing Results using Custom WaveView
For this analysis, the .PRINT statement will generate a gsmlnaIP3.printhb0 file.
Assume you want to find out the output power through the load resistor at the
first tone when the input power is 0.1mW.
To view the file:
1. Type wv at the prompt to invoke Custom WaveView.
2. Use File > Import Waveform File and select the gsmlnaIP3.hb0 file.
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Example 3: Using HB Analysis for an Amplifier
3. Select the signal Pr(rload) [1,0] in the signal browser. Drag and drop the
signal in the waveform. The X-axis will be the input power and the Y-axis will
be the output power. The input and output power in dBm will be displayed.
4. To measure the 1dB compression point of the amplifier, select Measurement
from the tools menu. In the Measurement Tools window, select the All tab.
In the type section of the window, click on the RF radial button. In the
measurement section, P1dB will be selected by default. Click OK; this will
place a dynamic meter in the waveform.
5. Move the dynamic meter near the signal, the meter will show the 1dB
compression point, the linear gain of the amplifier and the input power where
the 1dB compression point is measured. For best results, the asymptotic
line drawn by the dynamic meter should overlay the linear portion of the
amplifier power curve.
6. Use Waveview > New to open a new waveform.
7. Select the signals Pr(rload) [1,0], Pr(rload) [2,-1], and Pr(rload) [2,0] in the
signal browser. Drag and drop the signals in the waveform.
8. Click the signal mode icon in the waveform and select the Pr(rload) [1,0] and
Pr(rload) [2,-1] signals by clicking on the waveform labels displayed in the
waveform.
9. The 3rd order intercept point is also measured by using the measurement
tool. In the measurement section, select IP3/SFDR. Click OK; this will place
a dynamic meter in the waveform.
10. Move the dynamic meter near the Pr(rload)[1,0] signal, the meter will show
the 3rd order intercept point and the input power where the 3rd order
intercept point is measured. For best results, the asymptotic lines drawn by
the dynamic meter should overlay the linear portion of the Pr(rload) [1,0] and
Pr(rload) [2,-1] signals.
Device Model Cards
The following is an NMOS model in cmos49_model.inc file used in the power
amplifier example. It is available in directory $<installdir>/demo/hspicerf/
examples.
HSPICE® User Guide: RF Analysis
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Chapter 3: HSPICE RF Tutorial
Example 3: Using HB Analysis for an Amplifier
**
** NMOS IC Quadrature VCO circuit for GPS local oscillator
**
** Twin differential negative resistance VCOs
** using NMOS transistors for varactors, coupled
** to produce quadrature resonances.
** Design based on 0.35um CMOS process.
**
** References:
** >P. Vancorenland and M.S.J. Steyaert, "A 1.57-GHz fully
**
integrated very low-phase-noise quadrature VCO,"
**
IEEE Trans. Solid-State Circuits, May 2002, pp.653-656.
** >J. van der Tang, P. van de Ven, D. Kasperkovitz, and A.
Roermund,
** "Analysis and design of an optimally coupled 5-GHz quadrature
**
LC oscillator," IEEE Trans. Solid-State Circuits, May 2002,
**
pp.657-661.
** >F. Behbahani, H. Firouzkouhi, R. Chokkalingam, S. Delshadpour,
**
A. Kheirkhani, M. Nariman, M. Conta, and S. Bhatia,
** "A fully integrated low-IF CMOS GPS radio with on-chip analog
** image rejection," IEEE Trans. Solid-State Circuits, Dec. 2002,
**
pp. 1721-1727.
**
** Setup for Harmonic Balance Analysis
**
** Oscillation Frequency: ~ 1575 MHz (GPS L1 frequency)
** Amplitude: ~5 Volts peak-to-peak (zero to 5V)
** Vdd: 2.5 V
**
**
** Simulation Options :
.option POST
**
.param Vtune=2.0 $ Failures: vtune=1
.param Cval=0.2p
*--------------------------------Vtune vc gnd DC Vtune
Vdd vdd gnd 2.5
*--------------------------------* First oscillator section
** Low-Q resonator with Vdd at center tap of inductors
R1a IP ri 100k $ These R's set the Q
R1b ri IN 100k
L1 IP vdd 16.5nH
L2 vdd IN 16.5nH
Cc1 IP gnd Cval $ I to Q
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Example 3: Using HB Analysis for an Amplifier
Cc2 IN gnd Cval $ -I to Q
** Differential fets
M1 IP IN cs gnd NMOS l=0.35u w=15u
M2 IN IP cs gnd NMOS l=0.35u w=15u
** Bias fet - bias at Vdd -- too high?
Mb cs vdd gnd gnd NMOS l=0.35u w=15u
** fets used as varactors
Mt1 vc IP vc gnd NMOS l=0.35u w=2u M=50
Mt2 vc IN vc gnd NMOS l=0.35u w=2u M=50
*--------------------------------** Second oscillator section
** Low-Q resonator with Vdd at center tap of inductors
R1a_b QP ri_b 100k $ These R's set the Q
R1b_b ri_b QN 100k
L1_b QP vdd 16.5nH
L2_b vdd QN 16.5nH
Cc1_b QP gnd Cval $ -Q to -I
Cc2_b QN gnd Cval $ -Q to I
** Differential fets
M1_b QP QN cs_b gnd NMOS l=0.35u w=15u
M2_b QN QP cs_b gnd NMOS l=0.35u w=15u
** Bias fet - bias at Vdd -- too high? 2nd in parallel
Mb_b cs_b vdd gnd gnd NMOS l=0.35u w=15u
** fets used as varactors
Mt1_b vc QP vc gnd NMOS l=0.35u w=2u M=50
Mt2_b vc QN vc gnd NMOS l=0.35u w=2u M=50
*
*------------------------------* Differentiators Coupling transistors for quadrature
*
.param Cdiff=0.14p difMsize=50u
vidiff dbias gnd 1.25
viqdiff vdcdif gnd 1.75
Midiff1 dQP dbias gnd gnd NMOS l=0.35u w=difMsize
Midiff2 dQN dbias gnd gnd NMOS l=0.35u w=difMsize
Midiff3 dIN dbias gnd gnd NMOS l=0.35u w=difMsize
Midiff4 dIP dbias gnd gnd NMOS l=0.35u w=difMsize
Cdiff1 dQP QP Cdiff
Cdiff2 dQN QN Cdiff
Cdiff3 dIN IN
Cdiff
Cdiff4 dIP IP
Cdiff
Mc_QP1 IP vdcdif dQP gnd NMOS l=0.35u w=difMsize
Mc_QN2 IN vdcdif dQN gnd NMOS l=0.35u w=difMsize
Mc_QN3 QP vdcdif dIN gnd NMOS l=0.35u w=difMsize
Mc_QP4 QN vdcdif dIP gnd NMOS l=0.35u w=difMsize
*------------------------------* Transient Analysis Test Bench
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Chapter 3: HSPICE RF Tutorial
Example 3: Using HB Analysis for an Amplifier
* Use to show oscillator start up
* 2mA pulse used to start oscillator
*iosc IP IN PULSE ( 0 2m .01n .01n .01n 10n 1u )
*.probe tran v(IP) v(IN)
*.print tran v(IP) v(IN)
*.TRAN .01n 10n
*-----------------------------* Harmonic Balance Test Bench
*
.sweepblock vtune_sweep
+ 0 5 0.2
+ 2 3 0.1
.HBOSC tones=1550e6 nharms=12
+ PROBENODE=IP,QN,4
+ sweep Vtune sweepblock=vtune_sweep
**
.phasenoise dec 10 100 1e7
.print phasenoise phnz
.probe phasenoise phnz
.print hb v(IP,IN) v(IP,IN)[1] v(QP,QN) v(QP,QN)[1]
.probe hb v(IP,IN) v(IP,IN)[1] v(QP,QN) v(QP,QN)[1]
.probe hb hertz[1][1]
*
* NMOS Device from MOSIS 0.35um Process
*
* BSIM3 VERSION 3.1 PARAMETERS
*
* DATE: Mar 8/00
* LOT: n9co
WAF: 07
* Temperature_parameters=Default
*
.MODEL NMOS NMOS (
LEVEL
= 49
+VERSION = 3.1
TNOM
= 27
TOX = 7.9E-9
+XJ
= 1.5E-7
NCH
= 1.7E17
VTH0 = 0.5047781
+K1
= 0.5719698
K2
= 0.0197928
K3
= 33.4446099
+K3B
= -3.1667861
W0
= 1E-5
NLX
= 2.455237E-7
+DVT0W = 0
DVT1W
= 0
DVT2W
= 0
+DVT0
= 2.8937881
DVT1
= 0.6610934
DVT2
= -0.0446083
+U0
= 421.8714618
UA
= -1.18967E-10 UB
= 1.621684E-18
+UC
= 3.422111E-11 VSAT
= 1.145012E5
A0
= 1.119634
+AGS
= 0.1918651
B0
= 1.800933E-6
B1
= 5E-6
+KETA
= 3.313177E-3
A1
= 0
A2
= 1
+RDSW = 984.149934
PRWG = -1.133763E-3 PRWB = -7.19717E-3
+WR
= 1
WINT
= 9.590106E-8
LINT
= 1.719803E-8
+XL
= -5E-8
XW
= 0
DWG
= -2.019736E-9
+DWB
= 6.217095E-9
VOFF
= -0.1076921
NFACTOR = 0
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Chapter 3: HSPICE RF Tutorial
Example 4: Using HBOSC Analysis for a Colpitts Oscillator
+CIT
= 0
CDSC
= 2.4E-4
CDSCD
= 0
+CDSCB = 0
ETA0
= 0.0147171
ETAB
= -7.256296E-3
+DSUB
= 0.3377074
PCLM
= 1.1535622
PDIBLC1 = 2.946624E-4
+PDIBLC2 = 4.171891E-3
PDIBLCB = 0.0497942
DROUT = 0.0799917
+PSCBE1 = 3.380501E9
PSCBE2 = 1.69587E-9
PVAG
= 0.4105571
+DELTA
= 0.01
MOBMOD = 1
PRT
= 0
+UTE
= -1.5
KT1
= -0.11
KT1L
= 0
+KT2
= 0.022
UA1
= 4.31E-9
UB1
= -7.61E-18
+UC1
= -5.6E-11
AT
= 3.3E4
WL
= 0
+WLN
= 1
WW
= -1.22182E-15
WWN
= 1.1657
+WWL
= 0
LL
= 0
LLN
= 1
+LW
= 0
LWN
= 1
LWL
= 0
+CAPMOD = 2
XPART
= 0.4
CGDO
= 3.73E-10
+CGSO
= 3.73E-10
CGBO
= 1E-11
CJ
= 8.988141E-4
+PB
= 0.8616985
MJ
= 0.3906381
CJSW
= 2.463277E-10
+PBSW
= 0.5072799
MJSW
= 0.1331717
PVTH0 = -0.0143809
+PRDSW = -81.683425
WRDSW = -107.8071189 PK2
= 1.210197E-3
+WKETA = -1.00008E-3
LKETA = -6.1699E-3
PAGS
= 0.24968
+AF
= 1.0
KF
= 1.0E-30
)
*
.END
The following is the BJT model file, bjt.inc used in oscillator example. It is
available in directory $installdir/demo/hspicerf/examples.
* RF Wideband NPN Transistor die SPICE MODEL
.MODEL RF_WB_NPN
NPN
+ IS
= 1.32873E-015
BF
= 1.02000E+002
+ NF
= 1.00025E+000
VAF
= 5.19033E+001
+ EG
= 1.11000E+000
XTI
= 3.00000E+000
+ CJE
= 2.03216E-012
VJE
= 6.00000E-001
+ MJE
= 2.90076E-001
TF
= 6.55790E-012
+ XTF
= 3.89752E+001
VTF
= 1.09308E+001
+ ITF
= 5.21078E-001
CJC
= 1.00353E-012
+ VJC
= 3.40808E-001
MJC
= 1.94223E-001
Example 4: Using HBOSC Analysis for a Colpitts
Oscillator
This section demonstrates HSPICE RF oscillator analysis using a single
transistor oscillator circuit. Oscillator analysis is an extension of Harmonic
Balance in which the base frequency itself is an unknown to be solved for. In
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Chapter 3: HSPICE RF Tutorial
Example 4: Using HBOSC Analysis for a Colpitts Oscillator
oscillator analysis, the user supplies a guess at the base frequency, and no
voltage or current source stimulus is needed.
To activate oscillator analysis, include a .HBOSC command with:
■
The TONE parameter set to a guess of the oscillation frequency.
■
The PROBENODE parameter set to identify an oscillating node or pair of
nodes. Always specify a pair of nodes; if only one node oscillates, specify
ground as the second node. To speed up the simulation, also supply a guess
at the magnitude of the oscillating voltage across these nodes.
■
The FSPTS parameter set to a frequency range and number of search
points. When you set FSPTS, HSPICE RF precedes the HBOSC analysis
with a frequency search in the specified range to obtain an optimal initial
guess for the oscillation frequency. This can accelerate the HB oscillator
convergence.
In conjunction with oscillator analysis, HSPICE RF can perform phase noise
analysis. Phase noise analysis measures the effect of transistor noise on the
oscillator frequency. Phase noise analysis is activated using the .PHASENOISE
command; this command sets a set of frequency points for phase noise
analysis. The .PRINT and .PROBE commands can be used to output phase
noise values.
The following netlist, osc.sp, simulates an oscillator, and performs phase noise
analysis. This example is included with the HSPICE RF distribution as pa.sp
and is available in directory $installdir/demo/hspicerf/examples.
38
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Chapter 3: HSPICE RF Tutorial
Example 4: Using HBOSC Analysis for a Colpitts Oscillator
Figure 3
Colpitts Oscillator
Use the .HBOSC command with the PROBENODE and FSPTS parameters set.
PROBENODE=emitter,0,4.27
Identifies the emitter node as an oscillating node, and provides a guess value
of 4.27 volts for the oscillation amplitude at the emitter node.
FSPTS=40,9e6,1.1e7
Causes an initial frequency search using 40 equally-spaced points between 9
and 11 MHz.
In the .PHASENOISE, .PRINT, and .PROBE commands:
.PHASENOISE V(emitter) dec 10 10k 1meg
Runs phase noise analysis at the specified offset frequencies, measured from
the oscillation carrier frequency. The frequency points specified here are on a
logarithmic scale, 10 points per decade, 10 kHz to 1 MHz.
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Chapter 3: HSPICE RF Tutorial
Example 4: Using HBOSC Analysis for a Colpitts Oscillator
■
.PROBE PHASENOISE PHNOISE and the similar .PRINT command
instruct HSPICE RF to output phase noise results to the osc.pn0 and
osc.printpn0 files.
**
** Uses emitter resistor limiting to keep output sinusoidal.
** Output can be taken at the emitter (eml node).
**
*--------------------------------------------------------* Options for Oscillator Harmonic Balance Analysis...
*
.OPTIONS post sim_accuracy=100 hbsolver=0
*--------------------------------------------------------* Bias NPN transistor for 5V Vce, 10mA Ic
* Emitter follower Colpitts design
Vcc collector 0
9V
Q1 collector base emitter emitter RF_WB_NPN
Re1
emitter
eml
100
RLoad eml
0
300
Rb1
collector base 4300
Rb2
base
0
5600
*
*--------------------------------------------------------* Capacitive feedback network
Ce
0
eml
100pF
Cfb base eml
100pF
Cbb base bb
470pF
Lb bb
0
6uH
*--------------------------------------------------------* Simulation control for automated oscillator analysis
*
.HBOSC tones=1.0e7 nharms=15
+PROBENODE=emitter,0,4.27
+FSPTS=40,9.e6,1.1e7
*
.PHASENOISE V(emitter) DEC 10 10K 1MEG
+METHOD=0 CARRIERINDEX=1
*
.print hbosc vm(eml) vp(eml) vr(emitter) vi(emitter)
.print hbosc vm(emitter) vp(emitter) P(Rload)
.print phasenoise phnoise
.probe phasenoise phnoise
.probe hbosc v(emitter) v(eml)
.include bjt.inc
.END
40
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Chapter 3: HSPICE RF Tutorial
Example 5: Using HBOSC Analysis for a CMOS GPS VCO
After you run this netlist, examine the osc.printhb0 file.
■
At the top is the oscillator frequency (about 10.14 MHz) and the .PRINT
HBOSC output.
■
The first 2 lines show that the eml node oscillates around 3V with an
amplitude of about 2.85V.
■
The emitter node oscillates around 4V with an amplitude of about 4.27V.
Also examine the osc.printpn0 file, which contains the phase noise results in
text form.
You can view the osc.hb0 and osc.pn0 files in Custom WaveView.
1. Type wv at the prompt to invoke Custom WaveView.
2. Use File > Import Waveform File and select the osc.hb0 file from the Open:
Waveform Files dialog box.
3. Select the v(emitter) signal in the signal browser. Double-click on the signal
name or drag and drop the signal in the waveform.
4. In the waveform, right-click in the name area of the panel containing the
signal v(emitter), left-click on the waveform label for v(emitter) in the
waveform. From the Panel menu, choose Signal 'v(emitter)' > To TimeDomain.
5. To accept the defaults for range and interval, click OK in the Convert to Time
domain window.
6. In a new waveform, you should now see a time domain waveform named
IFT.0|v(emitter).
To run a transient simulation for comparison:
1. Use the .TRAN 1n 10u command.
2. Add ic=10n to the Lb inductor.
The resulting waveforms should be the same as those from HB oscillator
analysis.
Example 5: Using HBOSC Analysis for a CMOS GPS
VCO
This second oscillator analysis example involves two negative resistance
oscillators coupled at 90 degrees. MOS capacitors are used as varactors. This
HSPICE® User Guide: RF Analysis
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41
Chapter 3: HSPICE RF Tutorial
Example 5: Using HBOSC Analysis for a CMOS GPS VCO
VCO topology is common for GPS applications and produces quadrature LO
outputs near 1550 MHz. The purpose of this example is to generate the VCO
tuning curve (output level and frequency as a function of tuning voltage), as
well as its phase noise characteristics as a function of tuning voltage.
The oscillator analysis is activated using the .HBOSC command:
■
The TONE parameter sets an oscillation frequency (near 1550 MHz).
■
The NHARMS parameter sets the harmonic content to 11th order.
■
The PROBENODE parameters identify the drain pins across the first oscillator
section as the pair of oscillating nodes. This is a differential oscillator, and
the approximate value for this differential amplitude is 6.1 V.
■
The FSPTS parameters set the search frequency range between 1500 and
1600 MHz.
■
The SWEEP parameters set a tuning voltage sweep from 2.0 to 3.2 V.
The following example is based on demonstration netlist gpsvco.sp, which is
available in directory $installdir/demo/hspicerf/examples. This netlist simulates
the oscillator schematic Figure 4 and performs phase noise analysis.
Figure 4
42
VCO Schematic
HSPICE® User Guide: RF Analysis
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Chapter 3: HSPICE RF Tutorial
Example 5: Using HBOSC Analysis for a CMOS GPS VCO
**
** NMOS IC Quadrature VCO circuit for GPS local oscillator
**
** Twin differential negative resistance VCOs using NMOS
** transistors for varactors, coupled to produce quadrature
** resonances.
** Design based on 0.35um CMOS process.
**
** References:
** >P. Vancorenland and M.S.J. Steyaert, "A 1.57-GHz fully
**
integrated very low-phase-noise quadrature VCO,"
**
IEEE Trans. Solid-State Circuits, May 2002, pp.653-656.
** >J. van der Tang, P. van de Ven, D. Kasperkovitz, and A.
Roermund,
** "Analysis and design of an optimally coupled 5-GHz quadrature
**
LC oscillator," IEEE Trans. Solid-State Circuits, May 2002,
**
pp.657-661.
** >F. Behbahani, H. Firouzkouhi, R. Chokkalingam, S. Delshadpour,
**
A. Kheirkhani, M. Nariman, M. Conta, and S. Bhatia,
** "A fully integrated low-IF CMOS GPS radio with on-chip analog
** image rejection," IEEE Trans. Solid-State Circuits, Dec. 2002,
**
pp. 1721-1727.
**
** Setup for Harmonic Balance Analysis
**
** Oscillation Frequency: ~ 1575 MHz (GPS L1 frequency)
** Amplitude: ~5 Volts peak-to-peak (zero to 5V)
** Vdd: 2.5 V
**
** HSPICE Simulation Options:
*.option delmax=1n ACCURATE LIST NODE
**
** HSPICE RF Simulation Options :
.option sim_accuracy=10
**
*.option savehb=’a.hbs’ loadhb=’a.hbs’
.option POST
.param Vtune=2.0 $ Failures: vtune=1
.param Cval=0.2p
*--------------------------------Vtune vc gnd DC Vtune
Vdd vdd gnd 2.5
*--------------------------------* First oscillator section
** Low-Q resonator with Vdd at center tap of inductors
R1a IP ri 100k $ These R’s set the Q
R1b ri IN 100k
L1 IP vdd 16.5nH
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Chapter 3: HSPICE RF Tutorial
Example 5: Using HBOSC Analysis for a CMOS GPS VCO
L2 vdd IN 16.5nH
Cc1 IP gnd Cval $ I to Q
Cc2 IN gnd Cval $ -I to Q
** Differential fets
M1 IP IN cs gnd NMOS l=0.35u w=15u
M2 IN IP cs gnd NMOS l=0.35u w=15u
** Bias fet - bias at Vdd -- too high?
Mb cs vdd gnd gnd NMOS l=0.35u w=15u
** fets used as varactors
Mt1 vc IP vc gnd NMOS l=0.35u w=2u M=50
Mt2 vc IN vc gnd NMOS l=0.35u w=2u M=50
*--------------------------------** Second oscillator section
** Low-Q resonator with Vdd at center tap of inductors
R1a_b QP ri_b 100k $ These R’s set the Q
R1b_b ri_b QN 100k
L1_b QP vdd 16.5nH
L2_b vdd QN 16.5nH
Cc1_b QP gnd Cval $ -Q to -I
Cc2_b QN gnd Cval $ -Q to I
** Differential fets
M1_b QP QN cs_b gnd NMOS l=0.35u w=15u
M2_b QN QP cs_b gnd NMOS l=0.35u w=15u
** Bias fet - bias at Vdd -- too high? 2nd in parallel
Mb_b cs_b vdd gnd gnd NMOS l=0.35u w=15u
** fets used as varactors
Mt1_b vc QP vc gnd NMOS l=0.35u w=2u M=50
Mt2_b vc QN vc gnd NMOS l=0.35u w=2u M=50
*
*------------------------------* Differentiators Coupling transistors for quadrature
*
.param Cdiff=0.14p difMsize=50u
vidiff dbias gnd 1.25
viqdiff vdcdif gnd 1.75
Midiff1 dQP dbias gnd gnd NMOS l=0.35u w=difMsize
Midiff2 dQN dbias gnd gnd NMOS l=0.35u w=difMsize
Midiff3 dIN dbias gnd gnd NMOS l=0.35u w=difMsize
Midiff4 dIP dbias gnd gnd NMOS l=0.35u w=difMsize
Cdiff1 dQP QP Cdiff
Cdiff2 dQN QN Cdiff
Cdiff3 dIN IN
Cdiff
Cdiff4 dIP IP
Cdiff
Mc_QP1 IP vdcdif dQP gnd NMOS l=0.35u w=difMsize
Mc_QN2 IN vdcdif dQN gnd NMOS l=0.35u w=difMsize
Mc_QN3 QP vdcdif dIN gnd NMOS l=0.35u w=difMsize
Mc_QP4 QN vdcdif dIP gnd NMOS l=0.35u w=difMsize
*-------------------------------
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Chapter 3: HSPICE RF Tutorial
Example 5: Using HBOSC Analysis for a CMOS GPS VCO
* Transient Analysis Test Bench
*
* stimulate oscillation with 2mA pulse
*iosc IP IN PULSE ( 0 2m .01n .01n .01n 10n 1u )
*.probe tran v(IP) v(IN)
*.print tran v(IP) v(IN)
*.TRAN .01n 10n
*-----------------------------* Harmonic Balance Test Bench
*
.sweepblock vtune_sweep
+ 0 5 0.2
+ 2 3 0.1
.HBOSC tones=1550e6 nharms=12
+ PROBENODE=IP,QN,4
+ sweep Vtune sweepblock=vtune_sweep
**
.phasenoise dec 10 100 1e7
.print phasenoise phnz
.probe phasenoise phnz
.print hb v(IP,IN) v(IP,IN)[1] v(QP,QN) v(QP,QN)[1]
.probe hb v(IP,IN) v(IP,IN)[1] v(QP,QN) v(QP,QN)[1]
.probe hb hertz[1][1]
*
* NMOS Device from MOSIS 0.35um Process
*
* BSIM3 VERSION 3.1 PARAMETERS
*
* DATE: Mar 8/00
* LOT: n9co
WAF: 07
* Temperature_parameters=Default
*
.MODEL NMOS NMOS (
LEVEL
= 49
+VERSION = 3.1
TNOM
= 27
TOX
= 7.9E-9
+XJ
= 1.5E-7
NCH
= 1.7E17
VTH0
= 0.5047781
+K1
= 0.5719698
K2
= 0.0197928
K3
= 33.4446099
+K3B
= -3.1667861
W0
= 1E-5
NLX
= 2.455237E-7
+DVT0W
= 0
DVT1W
= 0
DVT2W
= 0
+DVT0
= 2.8937881
DVT1
= 0.6610934
DVT2
= -0.0446083
+U0
= 421.8714618
UA
= -1.18967E-10 UB
= 1.621684E-18
+UC
= 3.422111E-11 VSAT
= 1.145012E5
A0
= 1.119634
+AGS
= 0.1918651
B0
= 1.800933E-6
B1
= 5E-6
+KETA
= 3.313177E-3
A1
= 0
A2
= 1
+RDSW = 984.149934
PRWG = -1.133763E-3 PRWB = -7.19717E-3
+WR
= 1
WINT
= 9.590106E-8
LINT
= 1.719803E-8
+XL
= -5E-8
XW
= 0
DWG
= -2.019736E-9
+DWB
= 6.217095E-9
VOFF
= -0.1076921
NFACTOR = 0
+CIT
= 0
CDSC
= 2.4E-4
CDSCD
= 0
HSPICE® User Guide: RF Analysis
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Chapter 3: HSPICE RF Tutorial
Example 5: Using HBOSC Analysis for a CMOS GPS VCO
+CDSCB = 0
ETA0
= 0.0147171
ETAB
= -7.256296E-3
+DSUB
= 0.3377074
PCLM
= 1.1535622
PDIBLC1 = 2.946624E-4
+PDIBLC2 = 4.171891E-3
PDIBLCB = 0.0497942
DROUT = 0.0799917
+PSCBE1 = 3.380501E9
PSCBE2 = 1.69587E-9
PVAG
= 0.4105571
+DELTA
= 0.01
MOBMOD = 1
PRT
= 0
+UTE
= -1.5
KT1
= -0.11
KT1L
= 0
+KT2
= 0.022
UA1
= 4.31E-9
UB1
= -7.61E-18
+UC1
= -5.6E-11
AT
= 3.3E4
WL
= 0
+WLN
= 1
WW
= -1.22182E-15
WWN
= 1.1657
+WWL
= 0
LL
= 0
LLN
= 1
+LW
= 0
LWN
= 1
LWL
= 0
+CAPMOD = 2
XPART
= 0.4
CGDO
= 3.73E-10
+CGSO
= 3.73E-10
CGBO
= 1E-11
CJ
= 8.988141E-4
+PB
= 0.8616985
MJ
= 0.3906381
CJSW
= 2.463277E-10
+PBSW
= 0.5072799
MJSW
= 0.1331717
PVTH0 = -0.0143809
+PRDSW = -81.683425
WRDSW = -107.8071189 PK2
= 1.210197E-3
+WKETA = -1.00008E-3
LKETA = -6.1699E-3
PAGS
= 0.24968
+AF
= 1.0
KF
= 1.0E-30
)
*
.END
The results of the analysis are displayed in Figure 5 on page 47, Table 6 on
page 48 Figure 7 on page 49, and Figure 8 on page 50 using Custom
WaveView for VCO waveforms, tuning curves, and phase noise response.
46
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Chapter 3: HSPICE RF Tutorial
Example 5: Using HBOSC Analysis for a CMOS GPS VCO
Figure 5
VCO Spectra Output
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Chapter 3: HSPICE RF Tutorial
Example 5: Using HBOSC Analysis for a CMOS GPS VCO
Figure 6
48
VCO Waveform Output
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Chapter 3: HSPICE RF Tutorial
Example 5: Using HBOSC Analysis for a CMOS GPS VCO
Figure 7
VCO Tuning Curves Output
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Chapter 3: HSPICE RF Tutorial
Example 6: Using Multi-Tone HB and HBAC Analyses for a Mixer
Figure 8
VCO Phase Noise Response
Example 6: Using Multi-Tone HB and HBAC Analyses
for a Mixer
The example in this section shows how to use HSPICE RF to analyze a circuit
driven by multiple input stimuli with different frequencies. Mixer circuits provide
a typical example of this scenario: in this case, there might be two input signals
(LO and RF), which are mixed to produce an IF output signal. In this case,
HSPICE RF offers two options:
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Example 6: Using Multi-Tone HB and HBAC Analyses for a Mixer
■
Multi-tone HB analysis: specify the LO and RF base frequencies as two
separate tones on the .HB command.
■
Periodic AC analysis (HBAC): if one of the inputs is a small-signal, you can
use a faster linear analysis to analyze its effect. For example, if a mixer’s LO
is a large signal, but RF is a small signal, a single-tone HB analysis using
the LO frequency can be combined with HBAC in place of a 2-tone HB
analysis.
To demonstrate both techniques, this example analyzes an ideal mixer built
using behavioral elements. It is based on demonstration netlist mix_tran.sp,
which is available in directory $installdir/demo/hspicerf/examples.
* Ideal mixer example: transient analysis
.OPTIONS POST
vlo lo 0 1.0 sin (1.0 0.5 1.0g 0 0 90)
rrf1 rf1 rf 1.0
g1 0 if cur='1.0*v(lo)*v(rf)' $ mixer element
c1 0 if q='1.0e-9*v(lo)*v(rf)' $ mixer element
rout if ifg 1.0
vctrl ifg 0 0.0
h1 out 0 vctrl 1.0 $ convert I to V
rh1 out 0 1.0
vrf rf1 0 sin (0 0.001 0.8GHz 0 0 114)
.tran 10p 10n
.opt sim_accuracy=100
.end
This example uses behavioral controlled current and charge sources to
simulate a mixer. The LO signal is driven by a 0.5 Volt sinusoid at 1 GHz, and
RF is driven by a 10mV signal at 800 MHz. The mixer output is the voltage at
node out, v(out).
Two-tone HB Approach
To analyze this circuit using 2-tone HB, add:
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Example 6: Using Multi-Tone HB and HBAC Analyses for a Mixer
■
HB source for LO: add HB 0.5 0 1 1 to the LO voltage source; this sets
the amplitude to 0.5, no phase shift for the first harmonic of the first tone,
which is 1 GHz.
■
HB source for RF: add HB 0.001 24 1 2 to the RF voltage source; this
sets the amplitude to 0.001, 24 degrees phase shift for the first harmonic of
the second tone (0.8 GHz).
■
An .HB command specifying both tones: .hb tones=1g 0.8g nharms=6 3;
only a small number of harmonics is required to resolve the signals.
The complete mix_hb.sp netlist for 2-tone HB analysis is then:
* Ideal mixer example: 2-tone HB analysis
.OPTIONS POST
vlo lo 0 1.0 sin (1.0 0.5 1.0g 0 0 90) HB 0.5 0 1 1
rrf1 rf1 rf 1.0
g1 0 if cur='1.0*v(lo)*v(rf)' $ mixer element
c1 0 if q='1.0e-9*v(lo)*v(rf)' $ mixer element
rout if ifg 1.0
vctrl ifg 0 0.0
h1 out 0 vctrl 1.0 $ convert I to V
rh1 out 0 1.0
vrf rf1 0 sin (0 0.001 0.8GHz 0 0 114) HB 0.001 24 1 2
.opt sim_accuracy=100
.hb tones=1g 0.8g nharms=6 3
.end
This example is available in directory $<installdir>/demo/hspicerf/examples.
HBAC Approach
To analyze this circuit using HBAC, start with the 2-tone HB analysis setup, and
modify it as follows:
■
Replace the RF HB signal with an HBAC signal: change HB 0.001 24 1
2 to HBAC 0.001 24; this deactivates the source for HB and activates it for
HBAC with the same magnitude and phase.
■
Specify the frequency in the .HBAC command.
■
Change the .HB command to single tone:
.HB tones=1g nharms=6
HBAC takes care of the second tone.
■
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Example 6: Using Multi-Tone HB and HBAC Analyses for a Mixer
.HBAC lin 1 0.8g 0.8g
This command runs an analysis at a single frequency point, 0.8 GHz. In
general, HBAC analysis can sweep the RF frequency over a range of values.
The following is the complete mix_hbac.sp netlist for HBAC analysis of this
simple mixer. This netlist also contains commands for performing periodic noise
analysis. It is available in directory $installdir/demo/hspicerf/examples.
* Ideal mixer example: HBAC analysis
.OPTIONS POST
vlo lo 0 1.0 sin (1.0 0.5 1.0g 0 0 90)
+ HB 0.5 0 1 1
rrf1 rf1 rf 1.0
g1 0 if cur='1.0*v(lo)*v(rf)' $ mixer element
c1 0 if q='1.0e-9*v(lo)*v(rf)' $ mixer element
rout if ifg 1.0
vctrl ifg 0 0.0
h1 out 0 vctrl 1.0 $ convert I to V
rh1 out 0 1.0
vrf rf1 0 sin (0 0.001 0.8GHz 0 0 114)
+ HBAC 0.001 24
.opt sim_accuracy=100
.hb tones=1g nharms=6
.hbac lin 1 0.8g 0.8g
* Noise analysis
.hbnoise v(out) rrf1 lin 40 0.1g 4g
.print hbnoise onoise nf
.probe hbnoise onoise nf
.end
Comparing Results
After running all three netlists above, you will have generated 3 output files:
■
mix_tran.tr0
■
mix_hb.hb0
■
mix_hbac.hb0
You can compare the results of the three analyses in Custom WaveView.
1. To run the netlists and start Custom WaveView, type:
hspicerf mix_tran.sp
hspicerf mix_hb.sp
hspicerf mix_hbac.sp
wv &
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Example 6: Using Multi-Tone HB and HBAC Analyses for a Mixer
2. Use File > Import Waveform File and select the mix_tran.tr0, mix_hb.hb0,
and mix_hbac.hb0 files from the Open: Waveform Files dialog box. A
histogram displays.
3. Select the v(out) signal from the mix_hb.hb0 file in the signal browser.
Double-click on the signal name or drag and drop the signal in the waveform.
You should see a histogram similar to the one from the mix_hb.hb0 file.
4. Convert the HB and HBAC histograms to time domain. In the waveform,
right-click in the name area of the panel containing the signal v(out), leftclick on the waveform label for v(out) from the mix_hb.hb0 file. From the
Panel menu, choose Signal 'v(out)' > To Time-Domain. To accept the
defaults for range and interval, click OK in the Convert to Time domain
window.
5. Repeat Step 4 for the v(out) signal from the mix_hbac.hb0 file.
6. Use Waveview > New to open a new waveform.
7. Select the v(out) signal from the mix_tran.tr0 file in the signal browser.
Double-click on the signal name or drag and drop the signal in the waveform.
8. Compare the time domain waveforms from the mix_hb.hb0 and
mix_hbac.hb0 files with the time domain waveform from the mix_tran.tr0 file.
In the file browser, click on IFT under derived waveforms. The signals
0|v(out) and 1|v(out) should appear in the signal browser. Select the 0|v(out)
and 1|v(out) signals and drag and drop them in the waveform. All three time
domain signals should be displayed in the same panel. The three signals
are almost indistinguishable from each other.
You can also use HBAC to perform noise analysis on RF circuits by using
the .HBNOISE command, which is included in the mix_hbac.sp netlist.
■
The .HBNOISE command invokes noise analysis, identifying an output
node where the noise is measured, an input noise source (in this case, rrf1)
which serves as a reference for noise figure computation, and a frequency
sweep for the noise analysis.
■
The .PRINT and .PROBE hbnoise commands instruct HSPICE RF to
save the output noise and noise figure at each frequency in the
mix_hbac.printpn0 and mix_hbac.pn0 output files.
This ideal mixer is noiseless, except for the resistors at the input and output.
The mix_hbac.lis file contains detailed data on the individual noise source
contributions of the resistors. You can view mix_hbac.printpn0 to see the output
noise and noise figure at each frequency. In WaveView, you can view
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Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency Circuit and a Ring Oscillator
mix_hbac.pn0 to plot the output noise and noise figure data as a function of
frequency.
Example 7: Using Shooting Newton Analysis on a
Driven Phase Frequency Circuit and a Ring Oscillator
Introduction
While the Harmonic Balance (HB) algorithm represents the circuit's voltage and
current waveforms as a Fourier series (a series of sinusoidal waveforms), the
Shooting Newton (SN) algorithm provides analysis capability for digital logic
circuits and RF components that require steady-state analysis, but operate with
waveforms that tend to be square instead of sinusoidal.
Simple examples of using the Shooting Newton analysis functions are
presented in this section:
■
Driven Phase Frequency Detector Example
■
Ring Oscillator Example
Shooting Newton Analysis Setup
To set up a time-domain, steady-state analysis, the HSPICE input netlist must
contain:
■
A .SN command to activate the analysis. The .SN command specifies:
■
The expected period of the steady-state waveforms, which must match the
period of any input waveforms. The period is specified in time domain units
(seconds). Alternatively, you may specify a frequency in Hz.
■
A time resolution, which is analogous to the transient analysis (.TRAN)
command’s TSTEP parameter and will affect the time step size selection. It
also affects the number of frequency terms used in small-signal analyses,
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Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency Circuit and a Ring Oscillator
such as periodic AC or noise analysis. The time resolution is typically
specified in seconds but, alternatively, may be specified in the frequency
domain as a number of harmonics.
■
A transient initialization time that is used by HSPICE RF to run a basic
transient simulation of this length before attempting Newton-Raphson
iterations to converge on a steady-state solution. This parameter is optional.
If it is not specified, the specified period is used as the initialization time. The
initial transient analysis is used for circuit stabilization before the steady
state solution is found. Larger initialization values typically result in
convergence that is more robust.
■
For oscillator circuits, a .SNOSC command is used to activate the analysis.
The .SNOSC command specifies:
■
The approximate frequency of oscillation specified either as a frequency (in
Hertz) or as the time domain period.
■
The number of high frequency harmonics. Alternatively, a time resolution in
seconds can be specified.
■
A transient initialization time that is used by HSPICE RF to run a basic
transient simulation of this length before attempting Newton-Raphson
iterations to converge on a steady state solution. This parameter is optional.
If it is not specified, the period of the specified frequency of oscillation is
used as the initialization time. For oscillators we recommend specifying a
transient initialization time since the default initialization time is usually too
short to effectively stabilize the circuit.
■
A node at which to probe for oscillation conditions.
■
If the tuning curve of a VCO is to be analyzed, the optional parameter
MAXTRINITCYCLES can be specified.
■
One or more signal sources for driving the circuit in SN analysis, if the circuit
is driven. In the case of autonomous oscillator analysis, no signal source is
required. The sources are required to be time domain sources and must
match the period specified in the .SN command.
Driven Phase Frequency Detector Example
This example demonstrates the Shooting Newton-based analysis of a driven
phase-frequency detector. Extracted portions of the input file are presented
below. The complete phasefreqdet.sp input file for this example is located in the
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Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency Circuit and a Ring Oscillator
following directory:
$installdir/demo/hspicerf/examples/
Figure 9
Driven Phase Frequency Detector
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Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency Circuit and a Ring Oscillator
* Phase Frequency Detector Example
*
.global vdd gnd
.options wl post
* DC sources
vsup vdd 0 DC 1.0
* Reference signal (sine wave)
vref xin gnd DC 0 sin( 0.5 0.5 0.5g)
* Input buffers (square up Ref sine wave)
xfin1 xin fin1 inv
xfin2 fin1 FIN inv3
* Compare signal (sine wave)
vcRef cin gnd DC 0 sin( 0.5 0.5 0.5g 0.0 0.0 phase)
$ phase shift
* Input buffers (square up compare sine wave)
xcfin1 cin cfin1 inv
xcfin2 cfin1 cFIN inv3
*
** Phase/frequency detector
xPFD cFIN FIN pdn pu phasedet
** Chargepump
xCP LFIN Ibias pdn pu chargepump
** Bias voltage
vIbias Ibias gnd 0.15
$ Sets charge pump bias!
Vload LFIN 0 0
* Harmonic Balance Test Bench
*
.param phase=0.0
$ phase shift in degrees
.opt snaccuracy=30
.SN tres=10p period=2n SWEEP phase POI 5 0.0 22.5 45.0 67.5 90.0
.SNNOISE V(pu,pdn) Vref
+ DEC 21 100 10MEG
$ offset frequency sweep
+ [0,1]
$ Take low frequency noise
*
.probe sn v(fin) v(cfin) v(pu) v(pdn) v(lfin) i(vibias)
.print snfd i(vload) i(vload) [0]
.probe snfd i(vload) i(vload) [0]
.probe SNNOISE ONOISE
.print SNNOISE ONOISE
.end
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Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency Circuit and a Ring Oscillator
During the analysis, the phase of the input signal is swept between 0 degrees
and 90 degrees using five equally spaced steps. This enables you to measure
the phase detector gain at the output load. The .SN command syntax specifies
specifies the expected period of the steady-state waveforms (2nS) and the time
resolution (10pS) in the time domain.
A periodic, time-varying AC noise analysis based on the Shooting Newton
algorithm is performed using the .SNNOISE command. The .SNNOISE
analysis requires an output node (v(pu, pdn)) where the noise is to be
measured, an input noise source (Vref) which serves as the reference for the
noise computation and, a frequency sweep for the noise analysis. Optionally,
an index term can be defined. The index term specifies the output frequency
band at which the noise is evaluated. For this case, you will evaluate the low
frequency noise of the phase frequency detector.
The time-domain signals v(cfin), v(fin), v(pu) and v(pdn), and v(lfin) are probed.
The gain of the phase frequency detector can be found by probing the
frequency domain value of v(lfin) at DC (frequency indices 0).
During the simulation, the simulation status is displayed on the screen. In
addition to the screen display, more detailed status, cpu time, and memory
usage information is also written to the phasefreqdet.lis file.
Viewing Results in Custom WaveView
You can view the time-domain, phasefreqdet.sn0 file, the frequency domain,
phasefreqdet.snf0 file, and the noise results, phasefreqdet.snpn0 file in Custom
WaveView:
1. Enter wv at the prompt to start Custom WaveView.
2. The time domain results are used to show the input and output waveforms
of the phase frequency detector. Use File > Import Waveform File to open
the phasefreqdet.sn0 file.
3. Select the input signals, v(cfin) and v(fin), and the output signals, v(pu) and
v(pdn) from the signal browser. Drag and drop the selected signals in the
waveform. Figure 10 on page 60 shows the waveforms for the selected input
and output signals.
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Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency Circuit and a Ring Oscillator
Figure 10
Phase Frequency Detector Signals
4. The frequency domain results are used to show the gain of the phase
frequency detector. Use File > Import Waveform File to open the
phasefreqdet.snf0 file.
5. Use Waveview > New to open a new waveform.
6. Select the signal i(vload):(0) from the signal browser. Drag and drop the
signal i(vload):(0) in the waveform. The signal is the DC component of the
i(vload) signal spectrum. By default, the magnitude and phase of the load
current are plotted. To measure the gain of the phase frequency detector
verses phase, only the magnitude is required. Figure 11 on page 61 shows
the gain of the phase frequency detector.
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Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency Circuit and a Ring Oscillator
Figure 11
Phase Frequency Detector Gain
7. Next, plot the output noise of the phase frequency detector. Use File >
Import Waveform File to open the phasefreqdet.snpn0
file.phasefreqdet.snpn0 file.
8. Use Waveview > New to open a new waveform.
9. Select the signal onoise() from the signal browser. Drag and drop the signal
onoise() in the waveform. The noise results are shown in Figure 12 on
page 62. This displays the noise at the output, v(pu, vpd) at each phase
value swept in the .SN command.
10. Change the X-axis scale to log by left clicking on the X-axis and selecting
Log Scale from the X-Axis menu.
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Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency Circuit and a Ring Oscillator
Figure 12
Phase Detector Output Noise
Ring Oscillator Example
The Shooting Newton algorithm provides fast and effective analysis for ring
oscillators. The ringoscSN.sp input file for this example is located in the
following directory:
$installdir/demo/hspicerf/examples/
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Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency Circuit and a Ring Oscillator
Figure 13
Ring Oscillator
.title ringosc
.subckt inv in out vdd
mn1 out in 0 0 nmos l=0.25u w=2u
mp1 out in vdd vdd pmos l=0.25u w=6u
.ends
vdd vdd 0 3
x1 1 2 vdd inv
x2 2 3 vdd inv
x3 3 4 vdd inv
x4 4 5 vdd inv
x5 5 6 vdd inv
x6 6 7 vdd inv
x7 7 1 vdd inv
c1 1 0 0.022p
.ic v(1)=3
.options post
.options snaccuracy=50
.snosc tones=335meg nharms=10 oscnode=1 trinit=10n
.phasenoise v(7) dec 10 100 10meg
.probe
.probe
.print
.probe
sn v(7)
snfd v(7)
phasenoise phnoise v(7)
phasenoise phnoise v(7)
.end
This analysis finds the oscillation frequency of the ring oscillator. Since the
circuit is an oscillator, no input source is required. The oscillator is started by
setting an initial condition at the input of the ring (node 1). In the .SNOSC
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Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency Circuit and a Ring Oscillator
command, the node that the analysis will probe for oscillation conditions is
specified, as well as the approximate frequency of oscillation. The number of
harmonics to include in the analysis is specified, as well.
The phase noise characteristics of the oscillator are analyzed by using the
.PHASENOISE command. The .PHASENOISE command requires that an
output node, pair of nodes, or a two-port element and a frequency sweep be
specified. The frequency sweep is used to calculate the phase noise analysis at
the specified offset frequencies, measured from the oscillation carrier
frequency. For this example phase noise analysis, the default Nonlinear
Perturbation (NLP) method is used.
The signals v(7) will be probed in both the frequency and time domain. The
measure statement is used to measure the fundamental frequency of the
oscillator.
Simulation Status Output
During the simulation, the simulation status is displayed on the screen. In
addition to the screen display, more detailed status, cpu time and memory
usage information is also written to the ringoscSN.lis file.
Viewing Results in Custom WaveView
You can view the time-domain, ringoscSN.sn0 file, the frequency domain,
ringoscSN.snf0 file, and the phase noise, ringoscSN.snpn0 file in Custom
WaveView.
1. Enter wv at the prompt to start Custom WaveView.
2. Use File > Import Waveform File to open the ringoscSN.sn0 file.
3. Select the signal v(7) from the signal browser. Drag and drop the signal v(7)
to the right side of waveform so that panels are opened in row / column
format. The time domain trace shown at the right side of Figure 14 on
page 65.
4. Use File > Import Waveform File to open the ringoscSN.snf0 file.
5. Select the signal v(7) from the signal browser. Drag and drop the signal v(7)
to the right side of waveform so that panels are opened in row / column
format. The frequency domain spectrum is shown at the left side of
Figure 14 on page 65.
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Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency Circuit and a Ring Oscillator
Figure 14
Ring Oscillator Output
6. Use File > Import Waveform File to open the ringoscSN.snpn0 file.
7. Use Waveview > New to open a new waveform.
8. Select the signal nlp_l(f) from the signal browser. Drag and drop the signal
nlp_l(f) signal in the waveform. Figure 15 on page 66 shows the resulting
phase noise results for the oscillator.
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Example 7: Using Shooting Newton Analysis on a Driven Phase Frequency Circuit and a Ring Oscillator
Figure 15
Ring Oscillator Phase Noise
Other Shooting Newton Analyses
The following Shooting Newton Analyses are also supported by HSPICE RF.
66
■
.SNFT is equivalent to the .FFT command in transient (.TRAN) analysis.
.SNFT uses Fourier transform to represent a time domain signal in the
frequency domain. For more information, see Shooting Newton with Fourier
Transform (.SNFT).
■
.SNAC is used to perform a linear analysis of a driven (or nonautonomous)
circuit, where the linear coefficients are modulated by a periodic, steadystate signal. The functionality is similar to the .HBAC command. For more
information, see Shooting Newton AC Analysis (.SNAC).
■
.SNXF is used to calculate transfer functions from an arbitrary number of
small signal sources to a designated output in a circuit under periodic steady
state conditions. For more information, see Shooting Newton Transfer
Function Analysis (.SNXF).
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RF Demonstration Input Files
RF Demonstration Input Files
The following is a listing of shipped demonstration files for illustrating HSPICE
RF functionality. All of these example files are available at:
$installdir/demo/hspicerf/examples
File Name
Description
acpr.sp
Envelope simulation example
bjt.inc
Transistor model library used by osc.sp
cmos49_model.inc
Transistor model library used by example circuits
cmos90nmWflicker.lib
Transistor model library used by phasefreqdet.sp
gpsvco.sp
Oscillator and Phase Noise analysis example
gsmlna.sp
LNA Linear analysis example
gsmlnaIP3_A.sp
3rd order intercept point example
mix_hb.sp
Mixer HB analysis example
mix_hbac.sp
MIxer HBAC analysis example
mix_snac.sp
Mixer Shooting Newton AC example
mix_tran.sp
Mixer transient analysis example
osc.sp
Oscillator tuning curve and phase noise analysis example
pa.sp
Power amplifier HB analysis example
pfdcpGain.sp
Shooting Newton analysis example
phasefreqdet.sp
Shooting Newton and noise analysis example
ringoscSN.sp
Shooting Newton and Phase Noise analysis example
tsmc018.m
Transistor model library used by ringoscSN.sp
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RF Demonstration Input Files
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Testbench Elements
4
Describes the syntax for the specialized elements supported by HSPICE RF for
high-frequency analysis and characterization.
Elements are local and sometimes customized instances of a device model
specified in your design netlist. For discussion of the syntax for the basic
elements (passive, multi-linear, port, and active available to both HSPICE RF
and HSPICE), see Chapter 8, Elements in the HSPICE User Guide: Simulation
and Analysis. Examples for HSPICE RF are noted in that chapter.
For descriptions of the standard device models on which elements (instances)
are based, see the HSPICE Reference Manual: Elements and Device Models
and the HSPICE Reference Manual: MOSFET Models. For signal integrity
applications see the HSPICE User Manual: Signal Integrity.
HSPICE RF supports several specialized elements for high-frequency analysis
and characterization.
The following topics are discussed in these sections.
■
Values for Elements
■
Ideal Transformer Format in HSPICE RF
■
DC Block and Choke Elements
■
Multi-Terminal Linear Elements
■
Port Element
■
Steady-State Voltage and Current Sources
■
Steady-State HB Sources
■
Phase Differences Between HB and SIN Sources
■
Behavioral Noise Sources
■
Function Approximations for Distributed Devices
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Chapter 4: Testbench Elements
Values for Elements
■
Complex Signal Sources and Stimuli
■
SWEEPBLOCK in Sweep Analyses
■
Clock Source with Random Jitter
■
References
Values for Elements
HSPICE RF accepts equation-based resistors and capacitors. You can specify
the value of a resistor or capacitor as an arbitrary equation, involving node
voltages or variable parameters. Unlike HSPICE, you cannot use parameters to
indirectly reference node voltages in HSPICE RF.
Ideal Transformer Format in HSPICE RF
The ideal transformer format simplifies modeling of baluns. Previously, baluns
were modeled using mutual inductors (K elements) with the IDEAL keyword.
Multiple L and K elements were needed for a given balun model. The ideal
transformer model allows modeling of a balun using a single L element.
In the ideal transformer format, no absolute inductance or reluctance values
are specified. Instead, the transformer’s coupling characteristics are specified
using inductor number-of-turns values. The behavior of the ideal transformer
depends on ratios of the inductors’ number of turns.
Syntax
Lxxx n1p n1n ... nNp nNn TRANSFORMER_NT=(nt1, ... , ntN)
70
Parameter
Description
Lxxx
Inductor element name. Must begin with L, followed by up to
1023 alphanumeric characters.
n1p n1n ... nNp nNn
Positive and negative terminal node names. The number of
terminals must be even. Each pair of reports represents the
location of an inductor.
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DC Block and Choke Elements
Parameter
Description
TRANSFORMER_NT Number of turns values. These parameters must match the
number of inductors.
The ideal transformer element obeys the standard ideal transformer equations:
ν
ν
νN
------1- = ------2- = … = ------nt 1
nt 2
nt N
i 1 nt 1 + i 2 nt 2 + …+ i N nt N = 0
Example
L1 1 0 0 2 3 0 transformer_nt=(1,2,2)
DC Block and Choke Elements
In HSPICE RF, you can specify an INFINITY value for capacitors and inductors
to model ideal DC block and choke elements. The following input syntax is for
the DC block (ideal infinite capacitor):
Syntax
Cxxx node1 node2 [C=] INFINITY [IC=val]
HSPICE RF does not support any other capacitor parameters for DC block
elements, because HSPICE RF assumes that the infinite capacitor value is
independent of temperature and scaling factors. The DC block acts as an open
circuit for all DC analyses. HSPICE RF calculates the DC voltage across the
circuit’s nodes. In all other (non-DC) analyses, a DC voltage source of this
value represents the DC block (that is, HSPICE RF does not then allow dv/dt
variations).
The following input syntax is for the Choke (ideal infinite inductor):
Syntax
Lxxx node1 node2 [L=] INFINITY [IC=val]
HSPICE RF does not support any other inductor parameters, because HSPICE
RF assumes that the infinite inductance value is independent of temperature
and scaling factors. The choke acts as a short circuit for all DC analyses.
HSPICE RF calculates the DC current through the inductor. In all other (non-
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Multi-Terminal Linear Elements
DC) analyses, a DC current source of this value represents the choke (that is,
HSPICE RF does not then allow di/dt variations).
Multi-Terminal Linear Elements
A multi-terminal linear element such as a transmission line is a passive element
that connects any two conductors at any distance apart. One conductor sends
the input signal through the transmission line, and the other conductor receives
the output signal from the transmission line. The signal is voltage between the
conductors that is transmitted from one end of the pair to the other end.
Scattering Parameter Data Element
All HSPICE and HSPICE RF analyses can use the S-element. For more
information about S-parameters, see S-parameter Modeling Using the Selement in the HSPICE Signal Integrity Guide.
Frequency-Dependent Multi-Terminal (S-element)
When used with the generic frequency-domain model (.MODEL SP), an Selement is a convenient way to describe the behavior of a multi-terminal
network.
The S-element describes a linear time-invariant system, and provides a series
of data that describe the frequency response of the system. The S-element is
particularly useful for high-frequency characterization of distributed passive
structures. A common use of the S-element is in microwave circuits such as
spiral inductors, because electronic devices in this frequency domain no longer
act as they do in low frequencies. In this case, distributed system parameters
must be considered. See the example below for an application of the state
space stamping to generate a frequency invariant modified nodal analysis
(NMA) matrix from frequency-dependent characteristics using the Shooting
Newton (.SN) algorithm.
For scattering parameter element and model syntax, see S-element Syntax
and S Model Syntax in the HSPICE User Manual: Signal Integrity.
Example
The following netlist and data file (test.rfm) show how the S-element “S1” uses
the “STAMP=YSTS” configuration which invokes the state space stamping to
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Multi-Terminal Linear Elements
generate a frequency invariant modified nodal analysis (NMA) matrix from
frequency-dependent characteristics. This stamping method allows the
Shooting-Newton algorithm (.SN) to obtain the steady state. Note that unless
RFM file input is given, the S-element first applies the rational function
approximation (equivalent behavior to RATIONAL_FUNCTION=1) to the
original S-parameters in order to generate the state space stamping.
======= main netlist =======
*** .SN with s-element example
P1 n1 gnd port=1 dc=1v ac=1v pulse(1 0 1n 1n 1n 10n 20n)
P2 n2 gnd port=2 dc=1v ac=1v pulse(1 0 1n 1n 1n 10n 20n)
S1 n1 n2 0 mname=s_model
.model s_model S n=2
+ rfmfile='test.rfm'
+ STAMP=YSTS
.SN tone=0.05Ghz nharms=32
.option post accurate
.end
The following is from the .lis file for this netlist.
======= rational function matrix file (test.rfm) ======
VERSION 200600 NPORT 2 MATRIX_TYPE Y SYMMETRIC PRECFAC 0.75 Z0 50 50
BEGIN 1 1
BEGIN_REAL 9
DC 2.10290261e-02
2.80562648113e+07
1.36806220992e+08
1.16867967247e+09
1.23552099406e+09
1.92568095149e+09
4.15005808751e+09
1.00149288271e+10
2.27536895845e+10
3.54118199282e+10
1.791888661818e+00
-5.313505935943e+01
2.840375731037e+06
-4.257158329976e+06
3.038955064913e+06
-8.058749095413e+06
3.846931398394e+06
1.702938150800e+05
-1.243885701867e+07
BEGIN_COMPLEX 5
5.53251427579e+05 1.28282249537e+06 -3.17377193705e-03 1.20935639131e-03
2.39642428296e+09 1.39710928734e+08 -1.99538130185e+07 6.93072640638e+07
2.41275272760e+09 4.88535891322e+09 2.92904966609e+04
4.08311621367e+04
9.49575839142e+08 -2.82753080087e+10 -1.69178467311e+05 1.42790736653e+04
3.74702282735e+10 2.26461714292e+1
6.18960971035e+06 2.73309486084e+05 END BEGIN 2 2 DC 2.10290261e02
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Port Element
BEGIN REAL 9
2.80562648113e+07
1.36806220992e+08
1.16867967247e+09
1.23552099406e+09
1.92568095149e+09
4.15005808751e+09
1.00149288271e+10
2.27536895845e+10
3.54118199282e+10
1.79188866181e+00
-5.31350593594e+01
2.84037573103e+06
-4.25715832997e+06
3.03895506491e+06
-8.05874909541e+06
3.84693139839e+06
1.70293815080e+05
-1.24388570186e+07
BEGIN_COMPLEX 5
5.53251427579e+05 1.28282249537e+06 -3.17377193705e-03 1.20935639131e-03
2.39642428296e+09 1.39710928734e+08 -1.99538130185e+07 6.93072640638e+07
2.41275272760e+09 4.88535891322e+09 2.92904966609e+04
4.08311621367e+04
9.49575839142e+08 -2.82753080087e+10 -1.69178467311e+05 1.42790736653e+04 3.74702282735e+10 2.26461714292e+10
6.18960971035e+06 2.73309486084e+05
END
Port Element
The port element identifies the ports used in LIN analysis and behaves as
either a noiseless impedance or a voltage source in series with the port
impedance for all other analyses (DC, AC, or TRAN). Each port element
requires a unique port number. If your design uses N port elements, your netlist
must contain the sequential set of port numbers, 1 through N. For example, in a
design containing 512 ports, you must number each port sequentially, 1 to 512.
Each port has an associated system impedance, zo. If you do not explicitly
specify the system impedance, the default is 50 ohms.
■
You can use this element as a pure terminating resistance or as a voltage or
power source.
■
You can use the RDC, RAC, RHB, RHBAC, and RTRAN values to override the
port impedance value for a particular analysis.
The port element accepts transient waveforms AM, EXP, PULSE, PWL, SFFM,
SIN, LFSR, and, for signal integrity usage, the PAT source (see Pattern
Source).
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Port Element
Port Element Syntax
Pxxx p n port=portnumber
+ $ **** Port Impedence ****
+ [Z0=val]
+ $ **** Voltage or Power Information ********
+ [DC mag] [AC mag phase] [HBAC mag phase]
+ [HB mag phase harm tone modharm modtone]
+ [transient_waveform] [ENCODE=DW8B10B] [RD_INIT=0|1]
+ [TRANFORHB=[0|1]] [DCOPEN=[0|1]]
+ $ **** Power Switch ********
+ [power=[0|1|2|W|dbm]]
+ $ **** Source Impedance Overrides ********
[RDC=val] [RAC=val]
+ [RHBAC=val] [RHB=val] [RTRAN=val]
Parameter
Description
port=portnumber
The port number. Numbered sequentially beginning with 1 with
no shared port numbers.
z0=val
Port impedance (Ohms). (Default: 50). Sets port characteristic
impedance used for .LIN analysis, sets port termination
impedance for other analyses, and also sets source impedance
when the port element is used as a signal source.
DC mag
DC voltage or power source value.
AC mag phase
AC voltage or power source value.
HBAC mag phase
(HSPICE RF) HBAC voltage or power source value.
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Port Element
Parameter
Description
HB mag phase harm tone
modharm modtone
(HSPICE RF) HB voltage, current, or power source value.
Multiple HB specifications with different harm, tone, modharm,
and modtone values are allowed.
■
■
■
phase is in degrees
harm and tone are indices corresponding to the tones
specified in the .HB statement. Indexing starts at 1
(corresponding to the first harmonic of a tone).
modtone and modharm specify sources for multi-tone
simulation. A source specifies a tone and a harmonic, and up
to 1 offset tone and harmonic (modtone for tones and
modharm for harmonics). The signal is then described as:
V(or I)=mag*cos(2*pi*
(harm*tone+modharm*modtone)*t + phase)
transient_waveform
(Transient analysis) Voltage or power source waveform. Any one
of waveforms: AM, EXP, PULSE, PWL, SFFM, SIN, or PRBS.
Multiple transient descriptions are not allowed.
ENCODE=DW8b10b
Keyword to specify 8b/10b encoding.
RD_INIT=0|1
Initial value of Running Disparity. The one bit memory that recalls
the bias of the last unbalanced code word is called the Running
Disparity.1: Specifies that a Running Disparity value of zero is
synonymous with negative Running Disparity (?).
■
■
76
0: Specifies that a Running Disparity value of one is
synonymous with negative Running Disparity (-)
1: Specifies that a Running Disparity value of one is
synonymous with positive Running Disparity (+).
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Port Element
Parameter
Description
TRANFORHB=[0|1]
■
■
(HSPICE RF) 0 (default): The transient description is ignored
if an HB value is given or a DC value is given. If no DC or HB
value is given and TRANFORHB=0, then HB analysis treats
the source as a DC source, and the DC source value is the
time=0 value.
1: HB analysis uses the transient description if its value is
VMRF, SIN, PULSE, PWL, or LFSR. If the type is a nonrepeating PWL source, then the time=infinity value is used as
a DC analysis source value. For example, the following
statement is treated as a DC source with value=1 for HB
analysis:
v1 1 0 PWL (0 0 1n 1 1u 1)
+ TRANFORHB=1
In contrast, the following statement is a 0V DC source:
v1 1 0 PWL (0 0 1n 1 1u 1)
+ TRANFORHB=0
The following statement is treated as a periodic source with a
1us period that uses PWL values:
v1 1 0 PWL (0 0 1n 1 0.999u 1 1u 0) R
+ TRANFORHB=1
To override the global TRANFORHB option, explicitly set
TRANFORHB for a voltage or current source.
DCOPEN
Switch for open DC connection when DC mag is not set.
■
■
0 (default): P element behaves as an impedance termination.
1 : P element is considered an open circuit in DC operating
point analysis. DCOPEN=1 is mainly used in .LIN analysis so
the P element will not affect the self-biasing device under test
by opening the termination at the operating point.
RDC=val
(DC analysis) Series resistance (overrides z0).
RAC=val
(AC analysis) Series resistance (overrides z0).
RHBAC=val
(HSPICE RF HBAC analysis) Series resistance (overrides z0).
RHB=val
(HSPICE RF HB analysis) Series resistance (overrides z0).
RTRAN=val
(Transient analysis) Series resistance (overrides z0).
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Port Element
Parameter
Description
power=[0 | 1 | 2 | W | dbm]
(HSPICE RF) power switch
■
■
■
When 0 (default), element treated as a voltage or current
source.
When 1 or W, element treated as a power source, realized as
a voltage source with a series impedance. In this case, the
source value is interpreted as RMS available power in units of
Watts.
When 2 or dbm, element treated as a power source in series
with the port impedance. Values are in dbms.
You can use this parameter for transient analysis if the power
source is either DC or SIN.
Example
For example, the following port element specifications identify a 2-port network
with 50-ohm reference impedances between the “in” and “out” nodes.
P1 in gnd port=1 z0=50
P2 out gnd port=2 z0=50
Computing scattering parameters requires z0 reference impedance values.
The order of the port parameters (in the P-element) determines the order of
the S, Y, and Z parameters. Unlike the .NET command, the .LIN command
does not require you to insert additional sources into the circuit. To calculate
the requested transfer parameters, HSPICE automatically inserts these
sources as needed at the port terminals. You can define an unlimited number of
ports.
Using the Port Element for Mixed-Mode Measurement
To measure mixed mode S-parameters you can use a port element with three
terminals. Except for the number of external terminals, the syntax of the port
element remains the same. The LIN analysis function internally sets the
necessary drive mode (common/differential) of these mixed mode port
elements. For analyses other than the LIN analysis (such as DC, AC, TRAN,
and so on), the mixed-mode P-element acts as a differential driver that drives
positive nodes with half of their specified voltage and the negative nodes with a
negated half of the specified voltage. Figure 16 on page 79 shows the block
diagram of the mixed mode port element.
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P1 (Port element)
n1+
Z0
V+
Z0
Vn2-
n1_ref
Pl nl+ nl- nl_ref Zo=50
Figure 16
Mixed Mode Port Element
Steady-State Voltage and Current Sources
The I (current source) and V (voltage source) elements include extensions that
allow you to use them as sources of steady-state sinusoidal signals for HB and
HBAC analyses. When you use a power parameter to specify the available
power, you can also use these elements as power sources.
For a general description of the I and V elements, see Power Sources in the
HSPICE User Guide: Simulation and Analysis.
I and V Element Syntax
Vxxx p n
+ $ **** Voltage or Power Information ********
+ [[dc] mag] [ac [mag [phase]]] [HBAC [mag [phase]]]
+[SNAC [mag [phase]]]
+ [hb [mag [phase [harm [tone [modharm [modtone]]]]]]]
+ [transient waveform] [TRANFORHB=[1|0]]
+ $ **** Power Switch ********
+ [power=[0 | 1 | W | dbm]] [z0=val] [rdc=val] [rac=val]
+ [RHBAC=val] [rhb=val] [rtran=val]
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Steady-State Voltage and Current Sources
Ixxx p n
+ $ **** Current or Power Information ********
+ [[dc] mag] [ac [mag [phase]]] [HBAC [mag [phase]]]
+[SNAC [mag [phase]]]
+ [hb [mag [phase [harm [tone [modharm [modtone]]]]]]]
+ [transient waveform] [TRANFORHB=[1|0]]
+ $ **** Power Switch ********
+ [power=[0 | 1 | W | dbm]] [z0=val] [rdc=val] [rac=val]
+ [RHBAC=val] [rhb=val] [rtran=val]
Parameter
Description
[[dc] mag]
DC voltage or power source value. You don’t need to
specify DC explicitly (default=0).
[ac [mag [phase]]]
AC voltage or power source value.
[HBAC [mag [phase]]]
(HSPICE RF) HBAC voltage or power source value.
[SNAC [mag [phase]]]
(HSPICE RF) SNAC voltage or power source value.
[hb [mag [phase [harm
[tone [modharm
[modtone]]]]]]]
(HSPICE RF) HB voltage, current, or power source value.
Multiple HB specifications with different harm, tone,
modharm, and modtone values are allowed.
■
■
■
[transient waveform]
80
phase is in degrees
harm and tone are indices corresponding to the tones
specified in the .HB statement. Indexing starts at 1
(corresponding to the first harmonic of a tone).
modtone and modharm specify sources for multi-tone
simulation. A source specifies a tone and a harmonic,
and up to 1 offset tone and harmonic (modtone for
tones and modharm for harmonics). The signal is then
described as:
V(or I) = mag*cos(2*pi*
(harm*tone+modharm*modtone)*t + phase)
(Transient analysis) Any one of waveforms: AM, EXP,
PULSE, PWL, SFFM, or SIN. Multiple transient
descriptions are not allowed.
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Parameter
Description
[power=[0 | 1 | W | dbm]]
(HSPICE RF) Power Switch
■
■
■
When 0 (default), element treated as a voltage or
current source.
When 1 or W, element treated as a power source,
realized as a voltage source with a series impedance.
In this case, the source value is interpreted as RMS
available power in units of Watts.
When dbm, element treated as a power source in
series with the port impedance. Values are in dbms.
You can use this parameter for Transient analysis if the
power source is either DC or SIN.
[z0=val]
(LIN analysis) System impedance used when converting
to a power source, inserted in series with the voltage
source. Currently, this only supports real impedance.
■
■
When power=0, z0 defaults to 0.
When power=1, z0 defaults to 50 ohms.
You can also enter zo=val.
[rdc=val]
(DC analysis) Series resistance (overrides z0).
[rac=val]
(AC analysis) Series resistance (overrides z0).
[RHBAC=val]
(HSPICE RF HBAC analysis) Series resistance (overrides
z0).
[rhb=val]
(HSPICE RF HB analysis) Series resistance (overrides
z0).
[rtran=val]
(Transient analysis) Series resistance (overrides z0).
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Parameter
Description
[TRANFORHB=[0|1]]
■
■
0 (default): The transient description is ignored if an HB
value is given or a DC value is given. If no DC or HB
value is given and TRANFORHB=0, then HB treats the
source as a DC source, and the DC source value is the
time=0 value.
1: HB analysis uses the transient description if its value
is VMRF, SIN, PULSE, PWL, or LFSR. If the type is a
non-repeating PWL source, then the time=infinity value
is used as a DC source value. For example, the
following statement is treated as a DC source with
value=1 for HB:
v1 1 0 PWL (0 0 1n 1 1u 1) TRANFORHB=1
In contrast, the following statement is a 0V DC source:
v1 1 0 PWL (0 0 1n 1 1u 1) TRANFORHB=0
The following statement is treated as a periodic source
with a 1us period that uses PWL values:
v1 1 0 PWL (0 0 1n 1 0.999u 1 1u 0) R
TRANFORHB=1
To override the global TRANFORHB option, explicitly set
TRANFORHB for a V/I source.
Example 1
This example shows an HB source for a single tone analysis:
.hb tones=100MHz harms=7
I1 1 2 dc=1mA hb 3mA 0. 1 1
I1 is a current source with a the following time-domain description:
I1=1mA + 3mA*cos(2*pi*1.e8*t)
Example 2
This example shows HB sources used for a two-tone analysis:
.hb tones=1.e9 1.1e9 intmodmax=5
Vin lo 0 dc=0. hb 1.5 90 1 1
Vrf rf 0 dc=0. hb 0.2 0 1 2
These sources have the following time-domain descriptions:
Vin=1.5*cos(2*pi*1.e9*t - 90*pi/180) V
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Vrf = 0.2*cos(2*pi*1.1e9*t) V
Example 3
The following HB source uses a modtone and modharms:
.hb tones=2.e9 1.9e9 harms=5 5
Vm input gnd dc=0.5 hb 0.2 0. 1 1 -1 2
Vm has the following time-domain description:
Vm = 0.5 + cos(2*pi*1.e8*t)
Example 4
This example uses an HB source specified with a SIN source and
HBTRANINIT.
.hb tone=1.e8 harms=7
Vt 1 2 SIN(0.1 1.0 2.e8 0. 0. 90) tranforhb=1
Vt is converted to the following HB source:
Vt 1 2 dc=0.1 hb 1.0 0.0 2 1
Example 5
This example shows a power source (the units are Watts).
.hb tones=1.1e9 harms=9
Pt Input Gnd power=1 Z0=50. 1m 0. 1 1
Pt delivers 1 mW of power through a 50 ohm impedance.
Steady-State HB Sources
The fundamental frequencies used with harmonic balance analysis are
specified with the .HB TONES command. These frequencies can then be
referenced by their integer indices when specifying steady-state signal sources.
For example, the .HB specification given by the following line:
.HB TONES=1900MEG,1910MEG INTMODMAX=5
This specifies two fundamental frequencies: f [ tone = 1 ] = 1.9GHz and
f [ tone = 2 ] = 1.91GHz . Their mixing product at 10 MHz can then be referenced
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Steady-State HB Sources
using indices as f [ 2 ] – f [ 1 ] , while their 3rd order intermodulation product at 1.89
GHz can be referenced as 2f [ 1 ] – f [ 2 ] .
Steady-state voltage and current sources are identified with the HB keyword
according to
[HB [mag [phase [harm [tone [modharm [modtone]]]]]]]
The source is mathematically equivalent to a cosine signal source that follows
the equation
A cos ( ωt + φ)
where
A = mag
ω = 2π harm ⋅ f [ tone ] + modharm ⋅ f [ mo dtone ]
π
φ = --------- ⋅ phase
180
Values for tone and modtone (an optional modulating tone) must be nonnegative integers that specify index values for the frequencies specified with
the .HB TONES command. Values for harm (harmonic) and modharm
(modulating tone harmonic) must be integers (negative values are OK) that
specify harmonic indices.
Example 1
The following example is a 1.0 Volt (peak) steady-state cosine voltage source,
which is at the fundamental HB frequency with zero phase and with a zero volt
DC value:
Vsrc
in
gnd
DC
0
HB
1.0
0
1
1
Example 2
The following example is a steady-state cosine power source with 1.0mW
available power, which is implemented with a Norton equivalent circuit and a 50
ohm input impedance:
Isrc
in
gnd
HB
1.0e-3
0
1
1
power=1 z0=50
Example 3
Five series voltage sources sum to produce a stimulus of five equally spaced
frequencies at and above 2.44 GHz using modharm and modtone parameters.
These are commensurate tones (an integer relation exists); therefore, you only
need to specify two tones when invoking the HB analysis.
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Phase Differences Between HB and SIN Sources
.param Vin=1.0
.param f0=2440MEG
.param deltaf=312.5K
.param fcenter='f0 + 2.0*deltaf'
Vrfa
in
ina
HB
'Vin'
0
1
GHz
Vrfb
ina
inb
HB
'Vin'
0
1
2.4403125
GHz
Vrfc
inb
inc
HB
'Vin'
0
1
2.440
GHz
Vrfd
inc
ind
HB
'Vin'
0
1
2.4409375
GHz
Vrfe
ind
gnd
HB
'Vin'
0
1
GHz
.HB tones=fcenter,deltaf intmodmax=5
1
$ 2.440625
1
-1
2
$
1
-2
2
$
1
+1
2
$
1
+2
2
$ 2.44125
Phase Differences Between HB and SIN Sources
The HB steady-state cosine source has a phase variation compared to the
TRAN time-domain SIN source. The SIN source (with no offset, delay or
damping) follows the equation:
A sin ( ωt + φ)
while the HB sources follow
Equation 1
A cos ( ωt + φ)
In order for the two sources to yield identical results it is necessary to align
them by setting their phase values accordingly using:
Equation 2
Equation 3
A cos ( ωt + φ) = A sin ( ωt + φ + 90° )
A sin ( ωt + φ) = A cos ( ωt + φ – 90° )
To specify sources with matching phase for HB and TRAN analysis, use a
convention similar to:
Equation 4
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** Example #1 with equivalent HB and SIN sources
** SIN source is given +90 phase shift
.param freq1=2400MEG Vin=1.0
Vsrc in gnd DC 0 HB 'Vin' 0 1 1 SIN(0 'Vin' 'freq1' 0 0 90)
.HB tones=freq1 intmodmax=7
** Example #2 with equivalent HB and SIN sources
** HB source is given -90 phase shift to align with SIN
.param freq1=2400MEG Vin=1.0
Vsrc in gnd DC 0 HB 'Vin' -90 1 1 SIN(0 'Vin' 'freq1' 0)
.HB tones=freq1 intmodmax=7
** Example #3 with equivalent .HB and .TRAN sources
** SIN source is activated for HB using "TRANFORHB"
.param freq1=2400MEG Vin=1.0
Vsrc in gnd DC 0 SIN(0 'Vin' 'freq1' 0) TRANFORHB=1
.HB tones=freq1 intmodmax=7
Behavioral Noise Sources
In HSPICE RF, you can use the G-element to specify noise sources. Frequency
domain noise analyses (.NOISE, .HBNOISE, and .PHASENOISE) take these
noise sources into account.
You can attach noise sources to behavioral models. For example, you can use
a G-element with the VCCAP parameter to model a varactor, which includes a
noise model. You can also simulate effects such as substrate noise, including
its effect on oscillator phase noise. You can also use this G element syntax to
simulate behavioral descriptions of substrate noise during any frequency
domain noise analysis, which includes phase noise analysis. For example,
gname node1 node2 noise=’noise_equation’
gname node1 node2 node3 node4 noise=’noise_equation’
The first line creates a simple two-terminal current noise source, whose value
is described in A2/(Hz). The output noise generated from this noise source is:
noise_equation*H
Where H is the transfer function from the terminal pair (node1,node2) to the
circuit output, where HSPICE RF measures the output noise.
The second line produces a noise source correlation between the
(node1,node2) and (node3,node4) terminal pairs. The resulting output noise is
calculated as noise_equation*sqrt(H1*H2*); where,
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■
H1 is the transfer function from (node1,node2) to the output
■
H2 is the transfer function from (node3,node4) to the output.
The noise_equation expression can involve node voltages and currents through
voltage sources.
For the PAC phasenoise simulation to evaluate the frequency-dependent noise,
the frequency-dependent noise factor in the phasenoise must be expressed in
between the parentheses. For example:
gname node1 node2 noise = '(frequency_dependent_noise)*
bias_dependent_noise'
This is only true when the total noise can be expressed in this form and when
the frequency-dependent noise can be evaluated in the PAC phasenoise
simulation. You can also input the behavioral noise source as a noise table with
the help of predefined Table() function. The Table() function takes two formats:
■
Noise table can be input directly through the Table() function. For example:
gname node1 node2 noise = 'Table(arg1,f1,v1,f2,v2,......)'
■
The f1,v1,f2,v2,..... parameters describe the noise table. When arg1 == f1,
the function returns v1. The arg1 can be an expression of either HERTZ,
bias, or both. For example, arg1 = 'HERTZ * 1.0E+3'.
■
The noise table can be input through a .DATA structure:
.DATA d1
+ x y
+ f1 v1
+ f2 v2
.ENDDATA
gname node1 node2 noise = 'TABLE(arg1,d1)'
The x, y parameters in the DATA structure are two placeholder strings that can
be set to whatever you prefer even if they are in conflict with other parameters
in the netlist. The arg1 parameter can be an expression of HERTZ and bias.
When arg1 == f2, the function will return v2.
Using Noise Analysis Results as Input Noise Sources
SN phase noise and phase noise analyses can output simulation results as
ASCII data in *.printsnpn0 files for SNOSC and SNNOISE. By extending
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the E and G voltage-controlled source syntax, the phase noise data in ASCII
phase noise files can used as input for specifying behavioral noise sources
Usage Model
The syntax for the voltage controlled voltage (E) or current (G) source is as
follows:
Exxx node1 node2 noisefile='filename' [mname='measname']
Gxxx node1 node2 noisefile='filename' [mname='measname']
Where,
noisefile='filename' is the name of the ASCII phase noise data file. The
file name is typically designated as 'design.printsnpn0', for a .SNOSC phase
noise analysis or .SNNOISE analysis. But it also supports .PHASENOISE,
.HBNOISE, .NOISE, and .ACPHASENOISE outputs.
mname='measname' is used to select the appropriate noise measurement
name to be taken from the *.printpn0 file.
measname can be one of the following:
■
NLP_L(f) - selects the nlp_L(f) phase noise data in units of dBc/Hz
■
PAC_L(f) - selects the pac_l(f) phase noise data in units of dBc/Hz
■
BPN_L(f) - selects the bpn_l(f) phase noise data in units of dBc/Hz
■
ONOISE - selects the onoise data based on .SNNOISE analysis
The following syntaxes are supported in both HSPICE RF and HSPICE:
■
Exxx n1 n2 noise data=dataname
■
Exxx n1 n2 noise data=datablock
■
Exxx n1 n2 noisefile='filename'
■
Exxx n1 n2 noise='expression'
■
Exxx n1 n2 noise='Table(arg1,f1,v1,f2,v2...)'
■
Exxx n1 n2 noise='Table(arg1,dotDataBlockName)', where
dotDataBlockName is the .data statement reference
Power Supply Current and Voltage Noise Sources
You can implement the power supply noise source with G and E elements. The
G-element for the current noise source and the E-element for the voltage noise
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source. As noise elements, they are two-terminal elements that represent a
noise source connected between two specified nodes.
Syntax
Expression form
Gxxx node1 node2 noise=‘expression’
Exxx node1 node2 noise=‘expression’
The G noise element represents a noise current source and the E noise
element represents a noise voltage source. The xxx parameter can be set with
a value up to 1024 characters. The node1 and node2 are the positive and
negative nodes that connect to the noise source. The noise expression can
contain the bias, frequency, or other parameters.
Data form
Gxxx node1 node2 noise data=dataname
Exxx node1 node2 noise data=dataname
.data dataname
+ pname1 pname2
+ freq1 noise1
+ freq2 noise2
+ ...
.enddata
The data form defines a basic frequency-noise table. The .DATA statement
contains two parameters: frequency and noise to specify the noise value at
each frequency point. The unit for frequency is hertz, and the unit for noise is
A2/Hz (for G current noise source) or V2/Hz (for E voltage noise source).
Example
The following netlist shows a 1000 ohm resistor (g1) using a G-element. The
g1noise element, placed in parallel with the g1 resistor, delivers the thermal
noise expected from a resistor. The r1 resistor is included for comparison: The
noise due to r1 should be the same as the noise due to g1noise.
* Resistor implemented using g-element
v1 1 0 1
r1 1 2 1k
g1 1 2 cur='v(1,2)*0.001'
g1noise 1 2
+ noise='4*1.3806266e-23*(TEMPER+273.15)*0.001'
rout 2 0 1meg
.ac lin 1 100 100
.noise v(2) v1 1
.end
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Function Approximations for Distributed Devices
Function Approximations for Distributed Devices
High-order rational function approximations constructed for distributed devices
used at RF frequencies are obtained in the pole-residue form (also known as
Foster canonical form). The popular method of recursive convolution also uses
this form.
HSPICE supports the pole-residue form for its frequency-dependent controlled
sources (G and E-elements). You can enter the pole-residue form directly
without first converting to another form.
Foster Pole-Residue Form for Transconductance or
Gain
The Foster pole-residue form for transconductance G(s) or gain E(s) has the
form:
A i∗ ⎞
⎛ Ai
-------------------------+
⎜
∑ ⎝ s – pi s – p ∗-⎟⎠
i
N
Equation 5
G ( s ) = k0 + k1 s +
i=1
Where,
■
k0, k1 are real constants
■
residues Ai and poles pi are complex numbers (or real as a special case of
complex
■
asterisk (*) denotes the expression's complex conjugate
Advantages of Foster Form Modeling
The advantages of Foster canonical form modeling are:
90
■
models high-order systems. It can theoretically model systems having
infinite poles without numerical problems.
■
equivalent to Laplace and Pole-zero models
■
popular method of recursive convolution uses this form.
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G and E-element Syntax
Transconductance G(s) form
Gxxx n+ n+ (Re{A1},
+ (Re{A2},
+ (Re{A3},
+ ...
FOSTER in+ in- k0
Im{A1})/ (Re{p1},
Im{A2})/ (Re{p2},
Im{A3})/ (Re{p3},
k1
Im{p1})
Im{p2})
Im{p3})
FOSTER in+ in- k0
Im{A1})/ (Re{p1},
Im{A2})/ (Re{p2},
Im{A3})/ (Re{p3},
k1
Im{p1})
Im{p2})
Im{p3})
Gain E(s) form
Exxx n+ n+ (Re{A1},
+ (Re{A2},
+ (Re{A3},
+ ...
In this syntax, parentheses, commas, and slashes are separators—they have
the same meaning as a space. A pole-residue pair is represented by four
numbers (real and imaginary part of the residue, then real and imaginary part
of the pole).
You must make sure that Re[pi]<0; otherwise, the simulations will certainly
diverge. Also, it is a good idea to assure passivity of the model (for an N-port
admittance matrix Y, Re{Y} should be positive-definite), or the simulation is
likely to diverge).
Example
To represent a G(s) in the form,
Equation 6
( 0.001 – j0.006 )
0.0008 - --------------------------------------------------------------------+
+
s + ---------------------------10
8
10
s – ( – 1 × 10 + j1.8 × 10 )
s + 1 × 10
(
0.001
+
j0.006
)
-------------------------------------------------------------------8
10
s – ( – 1 × 10 – j1.8 × 10 )
G ( s ) = 0.001 + 1 × 10
– 12
You would input:
G1 1 0 FOSTER 2 0 0.001 1e-12
+(0.0004, 0)/(-1e10, 0) (0.001, -0.006)/(-1e8, 1.8e10)
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Note:
In the case of a real poles, half the residue value is entered,
because it's essentially applied twice. In the above example, the
first pole-residue pair is real, but we still write it as “A1/(s-p1)+A1/
(s-p1)”; therefore, 0.0004 is entered rather than 0.0008.
Complex Signal Sources and Stimuli
To predict radio-frequency integrated circuit (RFIC) performance, some
analyses require simulations that use representative RF signal sources. Among
the representative sources available in HSPICE RF is the complex modulated
RF source. Also known as the Vector Modulated source, it allows digital
modulation of an RF carrier using in-phase and quadrature components
created from a binary data stream.
Vector-Modulated RF (VMRF) Source
Digital RF waveforms are typically constructed by modulating an RF carrier with
in-phase (I) and quadrature (Q) components. In HSPICE RF, this is
accomplished using the Vector Modulated RF (VMRF) signal source.
The VMRF signal source function is supported both for independent voltage
and current sources (V and I elements), and with controlled sources (E, F, G,
and H elements).
■
When used with independent sources, a baseband data stream can be input
in binary or hexadecimal format, and the scheme used to divide the data into
I and Q signals can be specified.
■
With controlled VMRF sources, the modulating I and Q signals can be
separately specified with other signal sources (such as a PWL source) and
then used as control inputs into the VMRF source.
VMRF Implementation
The VMRF source is a mathematical implementation of the following block
diagram:
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l(t)
cos(wt)
Data in
Serial to
Parallel
S(t)
sin(wt)
Q(t)
The following equation calculates the time and frequency domain stimuli from
the quadrature modulated signal sources:
Equation 7
s ( t ) = I ( t ) cos ( 2πf c t + φ0 ) – Q ( t ) sin ( 2πfct + φ0 )
The discrete ideal I (in-phase) and Q (quadrature) signal components are
digital. Discrete values allow uniform scaling of the overall signal. HSPICE RF
generates data streams for the I and Q signals based on interpreting the data
string, breaking the data string into a binary representation, and then using the
bit pairs to assign values for the I and Q data streams.
For BPSK (binary phase shift keying) modulation, the discrete signals are
scaled so that
2
2
I + Q = 1:
Data In
I Data
Q Data
0
–1
------2
–1
------2
1
1
------2
1
------2
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For QPSK (quadrature phase shift keying) modulation, the data stream is
broken into bit pairs to form the correct I and Q values. This function is
represented as the serial to parallel converter:
Data In
I Data
Q Data
00
–1
------2
–1
------2
01
–1
------2
1
------2
10
1
------2
–1
------2
11
1
------2
1
------2
To generate a continuous-time waveform, the VMRF source takes the resulting
digital I and Q data streams and passes them through ideal filters. Rectangular
and Nyquist (raised-cosine) filter options are available. The output waveforms
are therefore band-limited according to the specified data rate.
Voltage and Current Source Elements
The V and I elements can include VMRF signal sources that you can use to
generate BPSK and QPSK waveforms.
V and I Element Syntax
Vxxx n+ n- VMRF [(] AMP=sa FREQ=fc PHASE=ph MOD=MOD
+ FILTER=FIL FILCOEF=filpar RATE=Rb BITSTREAM=data
+ [TRANFORHB=0/1] [)]
Ixxx n+ n- VMRF [(] AMP=sa FREQ=fc PHASE=ph MOD=MOD
+ FILTER=FIL FILCOEF=filpar RATE=Rb BITSTREAM=data
+ [TRANFORHB=0/1] [)]
94
Parameter
Description
Vxxx
Independent voltage source.
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Parameter
Description
Ixxx
Independent current source.
n+ n-
Positive and negative controlled source connecting nodes.
VMRF
Keyword that identifies and activates the Vector Modulated RF signal
source.
AMP
Signal amplitude (in volts or amps).
FREQ
Carrier frequency in hertz. Set fc=0.0 to generate baseband I/Q
signals. For harmonic balance analysis, the frequency spacing must
coincide with the .HB TONES settings.
PHASE
Carrier phase (in degrees). If fc=0.0,
■
■
■
MOD
One of the following keywords identifies the modulation method used
to convert a digital stream of information to I(t) and Q(t) variations:
■
■
FILTER
ph=0 and baseband I(t) is generated
ph=-90 and baseband q(t) is generated
Otherwise, s ( t ) = I ( t ) cos ( φ0 ) – Q ( t ) sin ( φ0 )
BPSK (binary phase shift keying)
QPSK (quadrature phase shift keying)
One of the following keywords identifies the method used to filter the
I and Q signals before modulating the RF carrier signal:
■
■
COS (raised cosine Nyquist filter)
RECT (rectangular filtering)
FILCOEF
Filter parameter for the COS filter: 0 ≤filpar ≤1
RATE
Bit rate for modulation (bits per second).
■
■
For BPSK modulation, the data rate and the symbol rate are the
same.
For QPSK modulation, the symbol rate is half the data rate.
The Rb value must be greater than zero.
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Parameter
Description
BITSTREAM A binary (b) or hexadecimal (h) string that represents an input data
stream.
Valid data string characters are:
■
■
0 or 1 for binary (b) mode.
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F, a, b, c, d, e, or f for
hexadecimal (h) mode.
For example:
■
■
01010011b (binary)
0F647A30E9h (hexadecimal)
You can also use the standard V source and I source options for non-transient
simulations (such as DC=val and AC=mag,ph) a with the VMRF source.
Example
BITSTREAM=01010010011100b
data
1/dr
BPSK I and Q Signals
.707
1/dr
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QPSK I Signal
.707
1/dr
QPSK Q Signal
.707
1/dr
The Rb parameter represents the data rate. The associated symbol rate
represents how fast the I and Q data streams change. The period for each bit of
data is:
Equation 8
1
T b = -----Rb
The symbol rate depends on whether you select BPSK or QPSK modulation:
■
For BPSK, the symbol rate is the same as the data rate:
S
■
R
BPSK
= Rb
For QPSK modulation, two bits are used to create each symbol so the
symbol rate is half the data rate.
R
S
QPSK
Rb
= -----2
The period for each symbol is computed as:
Equation 9
1
T s = ----Rs
This value is necessary for establishing the characteristics of Nyquist filters.
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The following equation calculates the raised cosine (COS) filter response:
1–α
f ≤-----------2T s
Equation 10
H rc ( f ) =
∫
Ts
0
1–α
2 πT s
T s cos -------- ⎛ f – ------------⎞
2α ⎝
2T s ⎠
1–α
1+α
------------ ≤ f ≤-----------2T s
2T s
1+a
f > -----------2T s
The VMRF signal source is designed primarily for TRAN and HB analyses, and
can generate baseband signals. You can also specify DC and AC values as
with any other HSPICE signal source:
■
In DC analysis, the VMRF source is a constant DC source.
■
In AC analysis, the source is a short or an open, unless you specify an AC
value.
■
In HB analysis, you must specify .OPTION TRANFORHB on the source
statement line. The TRANFORHB option supports the VMRF signal source as
well as the SIN, PULSE, and PWL sources.
The VMRF quadrature signal source typically involves an HF carrier signal that
is modulated with a baseband signal on a much different time scale. You must
set source and simulation control parameters appropriately to avoid timeconsuming simulations in both the time and frequency domains.
E, F, G, and H Element Statements
For E, F, G, and H elements, you can use the VMRF function to modulate I(t)
and Q(t) signals with a RF carrier signal. The I and Q signal are driven by PWL
sources that might be generated by an external tool, such as MATLAB. The
PWL source accepts a text file containing time and voltage (or current) pairs.
When the VMRF function is used with controlled sources, it is anticipated that
the in-phase (I) and quadrature (Q) signals are not digital, but continuous-time
analog signals. The VMRF function therefore includes no filtering, and merely
serves to create the complex modulation on the RF carrier.
Exxx n+ n- [VCVS] VMRF [(] Iin+ Iin- Qin+ Qin- FREQ=fc
+ PHASE=ph [SCALE=A] [)]
Fxxx n+ n- [CCCS] VMRF [(] VI VQ FREQ=fc PHASE=ph
+ [SCALE=A] [)]
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Gxxx n+ n- [VCCS] VMRF [(] Iin+ Iin- Qin+ Qin- FREQ=fc
+ PHASE=ph [SCALE=A] [)]
Hxxx n+ n- [CCVS] VMRF [(] VI VQ FREQ=fc PHASE=ph
+ [SCALE=A] [)]
Parameter
Description
Exxx
Voltage-controlled voltage source.
Fxxx
Current-controlled current source.
Gxxx
Voltage-controlled current source.
Hxxx
Current-controlled current source.
VCVS
Keyword for voltage-controlled voltage source.
CCCS
Keyword for current-controlled current source.
VCCS
Keyword for voltage-controlled current source.
CCVS
Keyword for current-controlled current source.
n+ n-
Positive and negative controlled source connecting nodes.
VMRF
Keyword that identifies and activates the vector-modulated RF signal
source.
Iin+ Iin-
Node names for input I(t) signal.
Qin+ Qin-
Node names for input Q(t) signal.
VI VQ
FREQ
Carrier frequency in Hertz. Set fc=0.0 to generate baseband I/Q
signals.
PHASE
Carrier phase (in degrees). If fc=0.0,
■
■
SCALE
ph=0 and baseband I(t) is generated
ph=-90 and baseband Q(t) is generated
Unit-less amplitude scaling parameter.
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SWEEPBLOCK in Sweep Analyses
Example
Emod1 inp1 inn1 VMRF It_plus It_neg Qt_plus Qt_neg
+ freq=1g phase=0 scale=1.5
SWEEPBLOCK in Sweep Analyses
You can use the .SWEEPBLOCK statement to specify complicated sweeps.
Sweeps affect:
■
DC sweep analysis
■
Parameter sweeps around TRAN, AC, or HB analyses
■
Frequency values used in AC or HBAC analyses
Currently, HSPICE supports the following types of sweeps:
■
■
■
Linear sweeps: sweeps a variable over an interval with a constant
increment. The syntax is one of the following:
•
variable start stop increment
•
variable lin npoints start stop
Logarithmic sweeps: sweeps a variable over an interval. To obtain each
point, this sweep multiplies the previous point by a constant factor. You can
specify the factor as a number of points per decade or octave as in:
•
variable dec npoints start stop
•
variable oct npoints start stop
Point sweeps: a variable takes on specific values that you specify as a list.
The syntax is:
variable poi npoints p1 p2 …
■
Data sweeps: a .DATA statement identifies the swept variables and their
values. The syntax is:
data=dataname
You can use the SWEEPBLOCK feature to combine linear, logarithmic, and point
sweeps, which creates more complicated sets of values over which a variable is
swept.
The .TRAN, .AC, .DC, and .HB commands can specify
SWEEPBLOCK=blockname as a sweep instead of LIN, DEC, OCT, and so forth.
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Also, you can use SWEEPBLOCK for frequency sweeps with
the .AC, .HBAC, .PHASENOISE, and .HBNOISE commands.
All commands that can use SWEEPBLOCK must refer to the SWEEPBLOCK
sweep type. In addition, you must specify SWEEPBLOCK as one of the syntax
types allowed for frequency sweeps with the .HBAC, .PHASENOISE,
and .HBNOISE commands.
Input Syntax
The SWEEPBLOCK feature creates a sweep whose set of values is the union of
a set of linear, logarithmic, and point sweeps. To specify the set of values in the
SWEEPBLOCK, use the .SWEEPBLOCK command. This command also assigns
a name to the SWEEPBLOCK. For example,
.SWEEPBLOCK swblockname sweepspec [sweepspec
+ [sweepspec […]]]]
You can use SWEEPBLOCK to specify DC sweeps, parameter sweeps, AC and
HBAC frequency sweeps, or wherever HSPICE accepts sweeps.
You can specify an unlimited number of sweepspec parameters. Each
sweepspec can specify a linear, logarithmic, or point sweep by using one of
the following forms:
start stop increment
lin npoints start stop
dec npoints start stop
oct npoints start stop
poi npoints p1 p2 …
Example
The following example specifies a logarithmic sweep from 1 to 1e9 with more
resolution from 1e6 to 1e7:
.sweepblock freqsweep dec 10 1 1g dec 1000 1meg 10meg
Using SWEEPBLOCK in a DC Parameter Sweep
To use the sweepblock in a DC parameter sweep, use the following syntax:
.DC sweepspec [sweepspec [sweepspec]]
Each sweepspec can be a linear, logarithmic, point, or data sweep, or it can be
in the form:
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variable SWEEPBLOCK=swblockname
The SWEEPBLOCK syntax sweeps the specified variable over the values
contained in the SWEEPBLOCK.
Example
.dc vin1 0 5 0.1 vin2 sweepblock=vin2vals
Using in Parameter Sweeps in TRAN, AC, and HB
Analyses
To use the sweepblock in parameter sweeps on .TRAN, .AC, and .HB
commands, and any other commands that allow parameter sweeps, use the
following syntax:
variable sweepblock=swblockname
Example 1
.tran 1n 100n sweep rout sweepblock=rvals
AC and HBAC analysis frequency sweeps can use
sweepblock=swblockname to specify the frequency values.
Example 2
.ac sweepblock=freqsweep
Limitations
■
You cannot use recursive SWEEPBLOCK specifications. That is,
a .SWEEPBLOCK command cannot refer to another SWEEPBLOCK to build its
list of values.
■
You cannot include data sweeps in a .SWEEPBLOCK statement.
Clock Source with Random Jitter
In many applications involving signal integrity, RF, analog, and mixed-signal
design, it is desirable to have an ideal signal source, such as a sine wave or
square wave, that also includes a non-ideal random drift in phase (jitter). Such
a source is useful for representing non-ideal clock sources during time-domain
transient simulation. Modeling jitter in this way can be used to examine eye102
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diagram behavior or study how jitter may propagate through a circuit or system.
A source with jitter is useful for representing non-ideal clock sources during
time-domain transient simulation.
The PERJITTER option allows you to add periodic jitter to SIN, COS and
PULSE time domain sources.
Syntax of SIN, COS, and Pulse Sources
The syntax of SIN source is:
Vxxx n+ n- SIN [(] vo va [freq [td [q [j ]]]] [)]
+ [PERJITTER=val SEED=val]]
Ixxx n+ n- SIN [(] vo va [freq [td [q [j ]]]] [)]
+ [PERJITTER=val SEED=val]]
Parameter
Description
Vxxx
Independent voltage source.
Ixxx
Independent current source.
PERJITTER
Period jitter
PWL
Keyword for piecewise linear.
PWLFILE
Text file containing the PWL data consisting of time and voltage (or
current) pairs. This file should not contain a header row, unless it is a
comment. The PWL source data is obtained by extracting col1 and
col2 from the file.
col1, [col2]
Time values are in col1 and voltage (or current) values are in col2. By
default, col1=1 and col2=2.
R
Repeat function. When an argument is not specified, the source
repeats from the beginning of the function. The argument repeated is
the time, in seconds, which specifies the start point of the waveform
being repeat. The repeat time must be less than the greatest time point
in the file.
TD
Time delay, in seconds, of the PWL function.
options
Any standard V or I source options.
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The sine wave behavior following the td time delay now becomes
Equation 11
V(t) + e
– ( t – td ) ⋅ θ
= V0 + Va ⋅
π
sin 2πf 0 ( t – t d ) + --------- ϕ + φt – d d
180
The Syntax of COS source is:
Vxxx n+ n- COS [(] vo va [freq [td [q][j]] [)]
+ [PERJITTER=val SEED=val]
Ixxx n+ n- COS [(] vo va [freq [td [q] [j]] [)]
+ [PERJITTER=val SEED=val]
The new cosine wave becomes
Equation 12
V(t) + e
– ( t – td ) ⋅ θ
= V0 + Va ⋅
π
cos 2 πf 0 ( t – t d + x ( t ) ) + --------- ϕ
180
The syntax for the PULSE source is:
Vxxx n+ n- PU[LSE] [(]v1 v2 [td [tr] [tf] [pw] [per] [)]
+ [PERJITTER=val SEED=val]
Ixxx n+ n- PU[LSE] [(]v1 v2 [td [tr] [tf] [pw] [per] [)]
+ [PERJITTER=val SEED=val]
The effect of jitter on the PULSE source results in random shifts of the rise and
fall transitions that takes place at
RISE edge: td + n ⋅ T 0 ≤t ≤td + tr + n ⋅ T 0
FALL edge: td + pw + n ⋅ T 0 ≤t ≤td + pw + tf + n ⋅ T 0
The jitter effect is equivalent to introducing random shifts in the period T 0
consistent with the 1st order jitter model based on Period Jitter.
A Gaussian random number generator computes the time deviation x ( t ) after
each leading edge of the clock sources. For flexibility, the SEED parameter
(integer) is supported for generating different random number sequences when
different SEED integers are used for initialization. SEED does not set a fixed
time deviation. It only changes the sequence of random samples. By HSPICE
(Monte Carlo) convention, the default value for SEED is 1.
An interpretation of PERJITTER is to view it as causing each period of the
PULSE/SIN/COS to be a random variable T j , where period T j will have a
Gaussian distribution about the (mean) given period value of T 0 . The standard
deviation of this Gaussian is the PERJITTER value (it is considered RMS
period jitter), which results in a bell curve distribution centered about period T 0 .
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Apply the following considerations when using PERJITTER:
■
T j should be forced to be between: 0 < T j < 2 ⋅ T 0 , since period cannot go
negative, and the curve should be symmetrical.
■
It is reasonable to require that 2 ⋅ PERJITTER < T 0 . Otherwise, the jitter
would result in very large period changes, and many would be T j < 0 .
■
To establish a waveform reference, the first period should be T 0 (i.e., no jitter
in the first period). This helps to establish good eye diagrams.
Example
As an alternative to using a Verilog-A module, you can generate a pseudorandom binary sequence (PRBS) using the following steps:
1. Construct your usual linear feedback shift register (LFSR) generator.
2. Construct a matching (T,tr,tf) PULSE source as a clock, but add jitter to it
with the PERJITTER keyword.
3. Use the PULSE source to gate (buffer) the LFSR output (through an ideal
AND gate, VCCS, and so forth).
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Chapter 4: Testbench Elements
References
References
[1] L.J. Greenstein and M.Shafi, Microwave Digital Radio, IEEE Press, 1988.
[2] N. Sheikholeslami and P. Kabal, “A Family of Nyquist Filters Based on
Generalized Raised-Cosine Spectra,” Proceedings of the 19th Biennial
Symposium on Communications (Kingston, Ontario), pages 131-135, June
1998.
[3] IEEE Standard Definitions of Physical Quantities for Fundamental
Frequency and Time Metrology - Random Instabilities, IEEE Std. 11391999.
[4] A. van der Ziel, Noise in Solid State Devices and Circuits, John Wiley &
Sons, © 1986.
[5] A. Demir, A. Mehrotra, and J. Roychowdhury, “Phase noise in oscillators: A
unifying theory and numerical methods for characterization,” IEEE Trans.
Circuits Syst. I, vol. 47, pp. 655-674, May 2000.
[6] A. Hajimiri, S. Limotyrakis, and T.H. Lee, “Jitter and phase noise in ring
oscillators,” IEEE J. Solid-State Circuits, vol. 34, no. 6, pp. 790-804, June
1999.
[7] Jitter Analysis Techniques for High Data Rates, Application Note 1432,
Agilent Technologies, Feb. 2003.[6] Characterization of Clocks and
Oscillators, NIST Technical Note 1337, National Institute of Standards and
Technology.
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5
5
Steady-State Harmonic Balance Analysis
Describes how to use harmonic balance analysis for frequency-driven, steadystate analysis.
HSPICE RF provides several analyses that support the simulation and analysis
of radio-frequency integrated circuits (RFICs). These analyses provide
simulation capabilities that are either much more difficult to perform, or are not
practically possible by using standard HSPICE analyses. The RF analyses
include:
■
Harmonic Balance (HB) for frequency-domain, steady-state analysis, see
Harmonic Balance Analysis on page 108.
■
Shooting Newton (SN) for frequency or time domain steady state analysis,
see Chapter 6, Steady-State Shooting Newton Analysis plus spectrum
analysis specific to the SN analysis (see Shooting Newton with Fourier
Transform (.SNFT).
■
Harmonic Balance oscillator analysis (HBOSC), see Harmonic Balance
Oscillator Analysis (.HBOSC) on page 144.
■
Shooting Newton oscillator analysis (SNOSC), see Oscillator Analysis
Using Shooting Newton (.SNOSC) on page 158.
■
Harmonic Balance AC (HBAC) for periodic AC analysis, see Chapter 8,
Large Signal Periodic AC, Transfer Function, and Noise Analyses, Multitone
Harmonic Balance AC Analysis (.HBAC) on page 189.
■
Shooting Newton AC analysis, see Shooting Newton AC Analysis (.SNAC)
on page 195.
■
Harmonic Balance Noise (HBNOISE) for periodic, time-varying AC noise
analysis (see Chapter 8, Large Signal Periodic AC, Transfer Function, and
Noise Analyses).
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Harmonic Balance Analysis
■
Shooting Newton noise analysis, see Shooting Newton Noise Analysis
(.SNNOISE) on page 209.
■
Harmonic balance transfer functions, see Multitone Harmonic Balance
Transfer Function Analysis (.HBXF) on page 226.
■
Shooting Newton transfer functions, see Shooting Newton Transfer Function
Analysis (.SNXF) on page 230
■
Frequency translation S-parameter extraction for describing N-port circuits
that exhibit frequency translation effects (see Frequency Translation SParameter (HBLIN) Extraction on page 256).
■
Envelope Analysis (ENV) (see Chapter 11, Envelope Analysis).
You can use steady-state analysis on a circuit if it contains only DC and
periodic sources. These analyses assume that all “start-up” transients have
completely died out with only the steady-state response remaining. Sources
that are not periodic or DC are treated as zero-valued in these analyses.
Harmonic Balance Analysis
Harmonic balance analysis (HB) is a frequency-domain, steady-state analysis
technique. In HSPICE RF, you can use this analysis technique on a circuit that
is excited by DC and periodic sources of one or more fundamental tones. The
solution that HB finds is a set of phasors for each harmonic signal in the circuit.
You can think of this solution as a set of truncated Fourier series. HSPICE RF
allows you to specify the solution spectrum to use in an analysis. HB analysis
then finds the set of phasors at these frequencies that describes the circuit
response. The result is a set of complex valued Fourier series coefficients that
represent the waveforms at each node in the circuit.
Linear circuit elements are evaluated in the frequency domain, while nonlinear
elements are evaluated in the time domain. The nonlinear response is then
transformed to the frequency domain where it is added to (or “balanced” with)
the linear response. The resulting composite response satisfies KCL and KVL
(Kirchoff's current and voltage laws) when the circuit solution is found.
Typical applications include performing intermodulation analysis, oscillator
analysis, and gain compression analysis, on amplifiers and mixers. HB analysis
also serves as a starting point for periodic AC and noise analyses.
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Harmonic Balance Analysis
Harmonic Balance Equations
We can write Kirchoff's current law in the time domain as:
t
Equation 13
f ( v, t ) = i ( v ( t ) ) + d q ( v ( t ) ) + ∫ y ( t – τ )v ( τ ) dτ + i s ( t ) = 0
dt
–∞
■
i(v(t)) represents the resistive currents from nonlinear devices
■
q represents the charges from nonlinear devices
■
y represents the admittance of the linear devices in the circuit
■
is represents the vector of independent current sources
■
v is a variable that represents the circuit unknowns, both node voltages and
branch currents, and f(v,t) is an error term that goes to zero when Kirchoff's
current law is satisfied.
Transforming this equation to the frequency domain results in:
Equation 14
Note:
F ( V ) = I ( V ) + ΩQ ( V ) + Y ( ω)V + I s = 0
Time-differentiation is transformed to multiplication by jω terms
(which make up the Ω matrix) in the frequency domain. The
convolution integral is transformed to a simple multiplication. The
Y matrix is the circuit’s modified nodal admittance matrix.
All terms above are vectors, representing the circuit response at each analysis
frequency.
The following equation shows the vector of (complex-valued) unknowns in the
frequency domain for a circuit with K analysis frequencies and N unknowns.
Equation 15
V = V ( 1,
0)
V ( 1,
1)
…V ( 1,
K – 1)
V ( 2,
0)
…V ( N,
K – 1)
HSPICE RF finds the unknown vector (V), which satisfies the system of
nonlinear equations shown in the equation above. This is done via the NewtonRaphson technique by using either a direct solver to factor the Jacobian matrix,
or an indirect solver. The indirect solver available in HSPICE RF is the
Generalized Minimum Residual (GMRES) Solver, a Krylov technique, and uses
a matrix-implicit algorithm.
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Features Supported
HB supports the following features:
■
All existing HSPICE RF models.
■
Unlimited number of independent input tones.
■
Sources with multiple HB specifications.
■
SIN, PULSE, VMRF, and PWL sources with TRANFORHB=1.
Prerequisites and Limitations
The following prerequisites and limitations apply to HB:
■
Requires one .HB statement.
■
Treats sources without a DC, HB, or TRANFORHB description as a zerovalue for HB unless the sources have a transient description, in which case,
the time=0 value is used as a DC value.
Input Syntax
Without SS_TONE
.HB TONES=F1 [F2 ... FN] [SUBHARMS=SH]
+ [NHARMS=H1, [H2 ...HN] [INTMODMAX=n]
+ [SWEEP parameter_sweep]
With SS_TONE
.HB TONES=F1 [F2 ... FN]
+ [NHARMS=H1, [H2 ...HN] [INTMODMAX=n]
+ [SS_TONE=n] [SWEEP parameter_sweep]
110
Parameter
Description
TONES
Fundamental frequencies.
SUBHARMS
Allows subharmonics in the analysis spectrum. The minimum nonDC frequency in the analysis spectrum is f/subharms, where f is the
frequency of oscillation.
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Harmonic Balance Analysis
Parameter
Description
NHARMS
Number of harmonics to use for each tone. Must have the same
number of entries as TONES. You must specify NHARMS,
INTMODMAX, or both.
INTMODMAX
INTMODMAX is the maximum intermodulation product order that
you can specify in the analysis spectrum. You must specify
NHARMS, INTMODMAX, or both.
SS_TONE
Small-signal tone number for HBLIN analysis. The value must be an
integer number. The default value is 0, indicating that no small
signal tone is specified. For additional information, see Frequency
Translation S-Parameter (HBLIN) Extraction on page 256.
SWEEP
Type of sweep. You can sweep up to three variables. You can specify
either LIN, DEC, OCT, POI, SWEEPBLOCK, DATA, OPTIMIZE, or
MONTE. Specify the nsteps, start, and stop frequencies using the
following syntax for each type of sweep:
■
■
■
■
■
■
■
■
LIN nsteps start stop
DEC nsteps start stop
OCT nsteps start stop
POI nsteps freq_values
SWEEPBLOCK nsteps freq1 freq2 ... freqn
DATA=dataname
OPTIMIZE=OPTxxx
MONTE=val
HB Analysis Spectrum
The NHARMS and INTMODMAX input parameters define the spectrum.
■
If INTMODMAX=N, the spectrum consists of all f=a*f1 + b*f2 + ... + n*fn
frequencies so that f>=0 and |a|+|b|+...+|n|<=N. The a,b,...,n coefficients are
integers with absolute value <=N.
■
If you do not specify INTMODMAX, it defaults to the largest value in the
NHARMS list.
■
If entries in the NHARMS list are > INTMODMAX, HSPICE RF adds the m*fk
frequencies to the spectrum, where fk is the corresponding tone, and m is a
value <= the NHARMS entry.
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Example 1
.hb tones=f1, f2 intmodmax=1
The resulting HB analysis spectrum={dc, f1, f2}
Example 2
.hb tones=f1, f2 intmodmax=2
The resulting HB analysis spectrum={dc, f1, f2, f1+f2, f1-f2, 2*f1, 2*f2}
Example 3
.hb tones=f1, f2 intmodmax=3
The resulting HB analysis spectrum={dc, f1, f2, f1+f2, f1-f2, 2*f1, 2*f2, 2*f1+f2,
2*f1-f2, 2*f2+f1, 2*f2-f1, 3*f1, 3*f2}
Example 4
.hb tones=f1, f2 nharms=2,2
The resulting HB analysis spectrum={dc, f1, f2, f1+f2, f1-f2, 2*f1, 2*f2}
Example 5
hb tones=f1, f2 nharms=2,2 intmodmax=3
The resulting HB analysis spectrum={dc, f1, f2, f1+f2, f1-f2, 2*f1, 2*f2, 2*f1-f2,
2*f1+f2, 2*f2-f1, 2*f2+f1}
Example 6
.hb tones=f1, f2 nharms=5,5 intmodmax=3
The resulting HB analysis spectrum={dc, f1, f2, f1+f2, f1-f2, 2*f1, 2*f2, 2*f1-f2,
2*f1+f2, 2*f2-f1, 2*f2+f1, 3*f1, 3*f2, 4*f1, 4*f2, 5*f1, 5*f2}
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HB Analysis Options
The following table lists the .OPTION command options specific to HB
analysis.
Table 4
HB Analysis Options
Option
Description
HBCONTINUE
Specifies whether to use the sweep solution from the
previous simulation as the initial guess for the present
simulation.
■
■
HBJREUSE
HBCONTINUE=1 (default): Use solution from previous
simulation as the initial guess.
HBCONTINUE=0: Start each simulation in a sweep from
the DC solution.
Controls when to recalculate the Jacobian matrix:
■
■
HBJREUSE=0 recalculates the Jacobian matrix at each
iteration.
HBJREUSE=1 reuses the Jacobian matrix for several
iterations, if the error is sufficiently reduced.
The default is 0 if HBSOLVER=1 or 2, or 1 if HBSOLVER=0.
HBJREUSETOL
Determines when to recalculate Jacobian matrix (if
HBJREUSE=1). The percentage by which HSPICE RF must
reduce the error from the last iteration so you can use the
Jacobian matrix for the next iteration. Must be a real number,
between 0 and 1. The default is 0.05.
HBKRYLOVDIM
Dimension of the Krylov subspace that the Krylov solver
uses. Must be an integer, greater than zero. Default is 40.
HBKRYLOVTOL
The error tolerance for the Krylov solver. Must be a real
number, greater than zero. The default is 0.01.
HBLINESEARCHFAC
The line search factor. If Newton iteration produces a new
vector of HB unknowns with a higher error than the last
iteration, then scale the update step by
HBLINESEARCHFAC, and try again. Must be a real number,
between 0 and 1. The default is 0.35.
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Table 4
HB Analysis Options (Continued)
Option
Description
HBMAXITER (or
HB_MAXITER)
Specifies the maximum number of Newton-Raphson
iterations that the HB engine performs. Analysis stops when
the number of iterations reaches this value. The default is
10000.
HBKRYLOVMAXITER (or
HB_KRYLOV_MAXITER
Specifies the maximum number of GMRES solver iterations
performed by the HB engine.
HBSOLVER
Specifies a preconditioner to solve nonlinear circuits.
■
■
■
HBSOLVER=0: invokes the direct solver.
HBSOLVER=1 (default): invokes the matrix-free Krylov
solver.
HBSOLVER=2: invokes the two-level hybrid timefrequency domain solver.
HBTOL
The absolute error tolerance for determining convergence.
Must be a real number that is greater than zero. The default
is 1.e-9.
LOADHB
LOADHB=’filename’ loads the state variable information
contained in the specified file. These values are used to
initialize the HB simulation.
SAVEHB
SAVEHB=’filename’ saves the final state (that is, the no
sweep point or the steady state of the first sweep point)
variable values from a HB simulation in the specified file. This
file can be loaded as the starting point for another simulation
by using a LOADHB option.
TRANFORHB
■
■
TRANFORHB=1: forces HB to recognize V/I sources that
include SIN, PULSE, VMRF, and PWL transient
descriptions, and to use them in analysis. However, if the
source also has an HB description, analysis uses the HB
description instead.
TRANFORHB=0: forces HB to ignore transient
descriptions of V/I sources, and to use only HB
descriptions.
To override this option, specify TRANFORHB in the source
description.
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Harmonic Balance Output Measurements
This section explains the harmonic balance output measurements you receive
after HSPICE runs an HB simulation.
Harmonic Balance Signal Representation
The HB cosine sources can be interpreted in real/imaginary and polar formats
according to:
v ( t ) = A cos ( αt + φ) = Re {Ae
j ( αt + φ)
jφ jωt
}= Re {Ae e }
jφ
Equation 16
= Re {Ae [ cos ( αt ) + j sin ( αt ) ] }
= Re {[ V R + jV I ] [ cos ( αt ) + j sin ( αt ) ] }
= V R cos ( αt ) – V I sin ( at )
= A cos ( φ) cos ( αt ) – A sin ( φ) sin ( αt )
Note that real/imaginary and polar formats are related with the standard
convention:
Equation 17
V R + jV I = Ae
jφ
V R = A cos ( φ)
V I = A sin ( φ)
A =
2
2
VR + VI
VI
tan φ = -----VR
The result of HB analysis is a complex voltage (current) spectrum at each
circuit node (or specified branch). Let a[i] be the real part and b[i] be the
imaginary part of the complex voltage at the ith frequency index. Conversion to
a steady-state time-domain waveform is given by the Fourier series expansion:
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Equation 18
v(t) = a[0] + a[1]*cos(2πf[1]*t) – b[1]*sin(2πf[1]*t)
+ a[2]*cos(2πf[2]*t) – b[2]*sin(2πf[2]*t)
+ a[3]*cos(2πf[3]*t) – b[3]*sin(2πf[3]*t)
+...
+ a[N]*cos(2πf[N]*t) – b[N]*sin(2πf[N]*t)
Where:
■
v(t) is the resulting time domain waveform.
■
N+1 is the total number of harmonics (including DC) in the frequency
domain spectrum of the *.hb0 file (the zero-th data point represents DC).
■
a[i] is the real component at the ith frequency
■
b[i] is the imaginary component at the ith frequency
■
f[i] is the ith frequency value (with i=0 representing the zero frequency DC
term). These frequencies need not be harmonically related.
This frequency domain (Fourier coefficient) representation can be converted
into a steady-state time domain waveform output representation by using
the .PRINT or .PROBE HBTRAN output option or by invoking the To Time
Domain function on complex spectra within Custom WaveView.
Output Syntax
This section describes the syntax for the HB .PRINT and .PROBE statements.
.PRINT and .PROBE Statements
.PRINT HB TYPE(NODES or ELEM)[INDICES]
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.PROBE HB TYPE(NODES or ELEM)[INDICES]
Parameter
Description
TYPE(NODES or ELEM) Specifies a harmonic type node or element.
TYPE can be one of the following:
■
■
■
■
Voltage type –
V = voltage magnitude and phase in degrees
VR = real component
VI = imaginary component
VM = magnitude
VP - Phase in degrees
VPD - Phase in degrees
VPR - Phase in radians
VDB - dB units
VDBM - dB relative to 1 mV
Current type –
I = current magnitude and phase in degrees
IR = real component
II = imaginary component
IM = magnitude
IP - Phase in degrees
IPD - Phase in degrees
IPR - Phase in radians
IDB - dB units
IDBM - dB relative to 1 mV
Power type – P
Frequency type –
‘HERTZ[i]’ (for single tone analysis), ‘HERTZ[i][j]’ (for
two-tone analysis) , ‘HERTZ[i][j][k]’ (for 3-tone analysis),
etc.
You must specify the harmonic index integer for the
HERTZ keyword. The frequency of the specified
harmonics is dumped.
NODES or ELEM can be one of the following:
■
■
■
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Voltage type – a single node name (n1), or a pair of node
names, (n1,n2)
Current type – an element name (elemname)
Power type – a resistor (resistorname) or port
(portname) element name.
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Parameter
Description
INDICES
Index to tones in the form [n1, n2, ..., nN], where nj is the
index of the HB tone and the HB statement contains N
tones. If INDICES is used, then wildcards are not
supported.
HB data can be transformed into the time domain and output using the
following syntax:
.PRINT hbtran ov1 [ov2 ... ]
.PROBE hbtran ov1 [ov2 ... ]
Where ov1 ... are the output variables to print or probe.
Outputting Phase Noise Source as ASCII Data Files Using
*.printpn0
HB phase noise and phase noise analyses can output simulation results as
ASCII data in *.printpn0 files for HBOSC and HBNOISE. By extending the E
and G voltage-controlled source syntax, the phase noise data in ASCII phase
noise files can used as input for specifying behavioral noise sources
Usage Model
The syntax for the voltage controlled voltage (E) or current (G) source is as
follows:
Exxx node1 node2 noise file='filename' [mname='measname']
Gxxx node1 node2 noise file='filename' [mname='measname']
Where file='filename' is the name of the ASCII phase noise data file. The
file name is typically designated as 'design.printpn0', for a .HBOSC phase
noise analysis or .HBNOISE analysis.
mname='measname' is used to select the appropriate noise measurement
name to be taken from the *.printpn0 file.
measname can be one of the following:
118
■
NLP_L(f) selects the nlp_L(f) phase noise data in units of dBc/Hz
■
PAC_L(f) - selects the pac_l(f) phase noise data in units of dBc/Hz
■
BPN_L(f) - selects the bpn_l(f) phase noise data in units of dBc/Hz
■
ONOISE - selects the onoise data based on .HBNOISE or .SNNOISE
analysis
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Calculating Power Measurements After HB Analyses
Two types of power measurements are available: dissipated power in resistors
and delivered power to port elements. The following subtle differences between
these two measurements are described in this section.
Power Dissipated in a Resistor
All power calculations make use of the fundamental phasor power relationship
given as the following equation, where voltage V and current I are complex
phasors given in peak values (not rms, nor peak-to-peak):
1
P rms = --- Re {VI∗ }
2
In the case of a simple resistor, its current and voltage are related according to
Vn=InR. The power dissipated in a resistor of (real) value R at frequency index
n is then given by:
Equation 19
2
Equation 20
Vn
P rms ( resistor ) [ n ] = ----------2R
Power Delivered to a Port Element
The port element can be either a source or sink for power. You can use a
special calculation that computes the power flowing into a port element even if
the port element itself is the source of that power. In the following figure is a
port element connected to a circuit (the port element may or may not include a
voltage source).
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Zo
In
+
+
Vs
Port
Element
Remainder
Of
Circuit
Vn
-
Figure 17
Port Element
Let Vn be the (peak) voltage across the terminals of the port element (at
frequency index n). Let In be the (peak) current into the (1st) terminal of the port
element (at frequency index n). Let Zo be the impedance value of the z0 port
element. Then, the power wave flowing into the terminals of the port element
(at frequency index n) can be computed according to:
Equation 21
1 Vn + Zo In
P in [ n ] = --- ---------------------2 2 Z
o
2
This power expression remains valid whether or not the port element includes
an internal voltage source at the same frequency. If the port element includes a
voltage source at the same frequency, you can use this power calculation to
compute the magnitude of the related large-signal scattering parameters.
If you expand the preceding formula, the power delivered to a port element with
(real) impedance Zo is given by
2
Equation 22
2
2
1 ⎧ Vn + Zo In
1
P rms ( port ) [ n ] = --- ⎨ ------------------------------------ + --- Re {V n I∗n
2⎩
2
4Z o
⎫
}⎬
⎭
This power value represents the power incident upon and delivered to the port
element's load impedance (Zo) due to other power sources in the circuit, and
due to reflections of its own generated power.
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If the port element is used as a load resistor (no internal source), the preceding
equation reduces to that for the simple resistor.
If you used the port element as a power source (with non-zero available power,
i.e. a non-zero Vs) and it is terminated in a matched load (Zo), the port power
measurement returns 0 W, because no power is reflected.
You can request power measurements in the form of complete spectra or in the
form of scalar quantities that represent power at a particular element. To
request a complete power spectrum, use the following syntax.
.PRINT HB P(Elem)
.PROBE HB P(Elem)
To request a power value at a particular frequency tone, use the following
syntax:
.PRINT HB P(Elem)[<n1<,n2<n3,...>>>]
.PROBE HB P(Elem)[<n1<,n2<,n3,...>>>]
The Elem is the name of either a Resistor (R) or Port (P) element, and n1,n2,
and n3 are integer indices used for selecting a particular frequency in the
Harmonic Balance output spectrum.
Example 1
Prints a table of the RMS power (spectrum) dissipated by resistor R1.
.PRINT HB P(R1)
Example 2
Outputs the RMS power dissipated by resistor R1 at the fundamental HB
analysis frequency following a one-tone analysis.
.PROBE HB P(R1)[1]
Example 3
Prints the power dissipated by resistor R1 at DC following a one-tone analysis.
.PRINT HB P(R1)[0]
Example 4
Outputs the RMS power dissipated by resistor R1 at the (low-side) 3rd order
intermodulation product following an HB two-tone analysis.
.PROBE HB P(R1)[2,-1]
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Example 5
Prints the RMS power dissipated by resistor R1 at the (high-side) 3rd order
intermodulation product following an HB two-tone analysis.
.PRINT HB P(R1)[-1,2]
Example 6
Outputs the RMS power (spectrum) delivered to port element Pload.
.PROBE HB P(Pload)
Example 7
Prints the RMS power delivered to port element Pload at the fundamental HB
analysis frequency following a one-tone analysis.
.PRINT HB P(Pload)[1] $
Example 8
Outputs the RMS power delivered to port element Pload at the (low-side) 3rd
order intermodulation product following an HB two-tone analysis.
.PROBE HB P(Pload)[2,-1]
Calculations for Time-Domain Output
In addition to a frequency-domain output, HB analysis also supports a timedomain output. The equivalent time-domain waveform is generated according
to the Fourier series expansion given by
Equation 23
V ( n1 )@time t = SUM OVERm ( REALV ( n1 ) [ m ] ) • cos "" ( Ω[ m ] • t ) – IMAG(V ( n1 ) [ m ] sin Ω[ m • t ] • t
Where m starts from 0 to the number of frequency points in the HB simulation.
The output syntax is
.PRINT [HBTRAN | HBTR] V(n1)
.PROBE [HBTRAN | HBTR] V(n1)
The output time ranges from 0 to twice the period of the smallest frequency in
the HB spectra.
Minimizing Gibbs Phenomenon
You can use the HB_GIBBS option for HBTRAN output to minimize Gibbs’
phenomenon that may occur in transforming a square-wave signal from the
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frequency domain to the time domain. The syntax is
.OPTION HB_GIBBS=n (defaults to zero, which is equivalent to not using it at
all).
N
The result is that the HBTRAN waveforms are filtered by a ( sin c ( x ) ) function
before being transformed to the time domain via FFT. This option applies only
to single-tone output. For example:
.option hb_gibbs = 2
...
.print hbtran v(2)
Figure 18
Upper square-wave signal shows HB_GIBBS = 2, while the lower shows
the option = 0
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Harmonic Balance Analysis
Output Examples
.PRINT HB P(rload)
.PROBE
.PRINT
.PROBE
.PRINT
.PROBE
$
$
HB V(n1,v2)
$
$
HB VP(out)[1]
$
$
$
HB P(Pout)[2,-1] $
$
HBTRAN V(n1)
$
HBTRAN V(n1, n2) $
$
RMS power (spectrum)
dissipated at the rload resistor
Differential voltage (spectrum)
between the n1,n2 nodes
Phase of voltage at the out
node, at the fundamental
frequency
RMS power delivered to the Pout
port, at third-order intermod
Voltage at n1 in time domain
Differential voltages between n1
and n2 node in time domain.
Using .MEASURE with .HB Analyses
■
For transient analysis (TRAN), the independent variable for
calculating .MEASURE is time.
■
For AC analysis, the independent variable for calculating .MEASURE is
frequency.
■
However, as with DC analysis, the use of a .MEASURE command is peculiar
for HB analysis, because it has no obvious independent variable.
In HSPICE RF, the independent variable for HB .MEASURE analysis is the first
swept variable specified in the .HB simulation control statement. This variable
can be anything: frequency, power, voltage, current, a component value, and so
on.
Example 1
For the following .HB simulation control statement, the independent variable is
the swept tone frequency, and the .MEASURE command values return results
based on this frequency sweep:
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* HARMONIC BALANCE tone-frequency sweep for amplifier
.param freq1=1.91e9 power=1e-3
.HB tones=freq1 nharms=10 sweep freq1 LIN 10 1.91e9 2.0e9
.MEASURE HB Patf0 FIND P(Rload)[1] AT=1.95e9 $ Power at
+ f0=1.95Ghz
.MEASURE HB Frq1W WHEN P(Rload)[1]=1. $ freq1 @ 1 Watt
.MEASURE HB BW1W TRIG AT=1.92e9 TARG P(Rload)[1] VAL=1.
+ CROSS=2 $ 1 Watt bandwidth
.MEASURE HB MaxPwr MAX P(Rload)[1] FROM=1.91e9 TO=2.0e9
+ $ Finds max output power
.MEASURE HB MinPwr MIN P(Rload)[1] FROM=1.91e9 TO=2.0e9
+ $ Finds min output power
Example 2
In the following example, the independent variable is the power variable, and
the .MEASURE values return results based on the power sweep. Units are in
Watts.
* HARMONIC BALANCE power sweep for amplifier
.param freq1=1.91e9 power=1e-3
.HB tones=freq1 nharms=10 sweep power DEC 10 1e-6 1e-3
.MEASURE HB Pat1uW FIND P(Rload)[1] AT=1e-6 $ Pout at 1uW
.MEASURE HB Pin1W WHEN P(Rload)[1]=1. $ Pin @ 1 Watt Pout
.MEASURE HB Prange1W TRIG AT=1.92e9 TARG P(Rload)[1] VAL=1.
+ CROSS=2
$ 1W oper. range
.MEASURE HB ssGain DERIV P(Rload)[1] AT=1e-5
+ $ relative power gain at 10uW input
.MEASURE HB Gain3rd DERIV P(Rload)[3] AT=1e-5
+ $ 3rd harmonic gain at 10uW input
.MEASURE HB PAE1W FIND ‘(P(Rload)[1]-power)/P(Vdc)[0]’
+ WHEN P(Rload)[1]=1 $ PAE at 1 Watt output
Example 3
In this example, the independent variable is again the power variable, and
the .MEASURE values return results based on the power sweep. This is a twotone sweep, where both input frequency sources are at the same power level in
Watts.
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HB Output Data Files
* HARMONIC BALANCE two-tone sweep for amplifier
* An IP3 calculation is made at 10uW in the sweep
.param freq1=1.91e9 freq2=1.91e9 power=1e-3
.HB tones=freq1,freq2 nharms=6,6 sweep power DEC 10 1e-6 1e-3
.MEASURE HB Pf1dBm FIND ’10.*LOG(P(Rload)[1,0]/1.e-3)’
+ AT=1e-5 $ P(f1) at 10uW input
.MEASURE HB P2f1_f2dBm FIND ’10.*LOG(P(Rload)[2,-1]/1.e-3)’
+ AT=1e-5 $ P(2f1-f2) at 10uW input
.MEASURE HB OIP3dBm PARAM = ‘0.5*(3.*Pf1dBm-P2f1_f2dBm)’
.MEASURE HB IIP3dBm PARAM = ‘OIP3dBm-Pf1dBm+20.0’
.MEASURE HB AM2PM DERIV VP(outp,outn)[1] AT=1e-5
+ $ AM to PM Conversion in Deg/Watt
If you do not specify an HB sweep, then .MEASURE assumes a single-valued
independent variable sweep.
You can apply the measurements to current, voltage, and power waveforms.
The independent variable for measurements is the swept variable (such as
power), not the frequency axis corresponding to a single HB steady state point.
HSPICE RF also supports the .MEASURE [HBTRAN | HBTR] ... syntax.
Similar to the .PROBE and .PRINT HBTR statements in the section
Calculations for Time-Domain Output on page 122, a .MEASURE HBTR
statement is applied on the signals obtained in the same way. Moreover, like a
.MEASURE statement in transient analysis, the independent variable in a
.MEASURE HBTR statement is time.
HSPICE RF optimization can read the data from .MEASURE HB and .MEASURE
HBTR statements. The optimization syntax in HSPICE RF is identical to that in
the HSPICE. Due to the difference in the independent variable between the
.MEASURE HB and .MEASURE HBTR statements, these two types of
measurements cannot be mixed in a HSPICE RF optimization. But a
.MEASURE HBTR statement can be combined with a .MEASURE PHASENOISE
statement (see Measuring Phase Noise with .MEASURE PHASENOISE on
page 172) and a .MEASURE HBNOISE statement (see Measuring HBNOISE
Analyses with .MEASURE on page 206) in a HSPICE RF optimization flow.
HB Output Data Files
The results of an HB analysis are complex spectral components at each
frequency point. The a[i] is the real part, and b[i] is the imaginary part of the
complex voltage at frequency index i. The conversion to a steady state timedomain is then given by the Fourier series expansion.
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HB Output Data Files
An HB analysis produces these output data files:
■
Output from the .PRINT HB statement is written to a .printhb# file.
•
The header contains the large signal fundamental frequencies.
•
The columns of data are labeled as HERTZ, followed by frequency
indices, and then the output variable names.
•
The sum of the frequency indices, multiplied by the corresponding
fundamental frequencies, add up to the frequency in the first column.
■
Output from the .PROBE HB statement is written to a .hb# file. It is in the
same format as the HSPICE transient analysis .tr# file. Besides the output
waveform, it contains the information of harmonic indices and basic tone
frequencies.
■
Output from the .PRINT HBTRAN statement is written to a .printhr# file. The
format is identical to a .print# file.
■
Output from the .PROBE HBTRAN statement is written to a .hr# file. The
format is identical to a .tr# file.
■
Reported performance log statistics are written to a .lis file:
•
Name of HB data file.
•
Simulation time:
DC operating point (op) time
HB time
Total simulation time
•
Memory used
•
Size of matrix (nodes * harmonics)
•
Final HB residual error
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HB Output Data Files
Errors and Warnings
Table 5 lists the errors messages and Table 6 on page 129 lists the warning
messages.
Table 5
128
HB Analysis Error Messages
File
Description
HB_ERR.1
Harmonic numbers must be positive non-zero.
HB_ERR.2
No .hb frequencies given.
HB_ERR.3
Negative frequency given.
HB_ERR.4
Number of harmonics should be greater than zero.
HB_ERR.5
Different number of tones, nharms.
HB_ERR.6
Bad probe node format for oscillator analysis.
HB_ERR.7
Bad format for FSPTS.
HB_ERR.8
Bad .hb keyword.
HB_ERR.9
Tones must be specified for .hb analysis.
HB_ERR.10
Nharms or intmodmax must be specified for .hb analysis.
HB_ERR.11
Source harmonic out of range.
HB_ERR.12
Source named in the tones list is not defined.
HB_ERR.13
Source named in the tones list does not have TRANFORHB
specified.
HB_ERR.14
Source named in the tones list has no transient description.
HB_ERR.15
Source named in the tones list must be HB, SIN, PULSE, PWL,
or VMRF.
HB_ERR.16
Tone specification for the source is inconsistent with its
frequency.
HB_ERR.17
HB oscillator analysis has reached the NULL solution.
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HB Output Data Files
Table 5
HB Analysis Error Messages (Continued)
File
Description
HB_ERR.18
Bad subharms format.
HB_ERR.19
Modtone may not be set to the same value as tone.
Table 6
HB Analysis Warning Messages
File
Description
HB_WARN.1
.hb multiply defined. Last one will be used.
HB_WARN.2
Tone specified for V/I source not specified in .HB command.
HB_WARN.3
HB convergence not achieved.
HB_WARN.4
Source specifies both HB and transient description. HB
description will be used.
HB_WARN.5
Source specifies exponential decay. HB will ignore it.
HB_WARN.6
Source specifies a non-positive frequency.
HB_WARN.7
Source does not fit the HB spectrum.
HB_WARN.8
Source cannot be used with the TRANFORHB option.
HB_WARN.9
Frequency not found from transient analysis
HB_WARN.10
.hb/.hbosc will be ignored due to .env/.envosc.
HB_WARN.11
HBTRANINIT does not support more than one input tone.
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Chapter 5: Steady-State Harmonic Balance Analysis
References
References
[1] S. Maas, Nonlinear Microwave Circuits, Chapter 3, IEEE Press, 1997.
[2] R. Gilmore and M.B. Steer, “Nonlinear Circuit Analysis Using the Method of
Harmonic Balance - A Review of the Art, Part I, Introductory Concepts.”
International Journal of Microwave and Millimeter-wave Computer-Aided
Engineering, Volume 1, No. 1, pages 22-37, 1991.
[3] R. Gilmore and M.B. Steer, “Nonlinear Circuit Analysis Using the Method of
Harmonic Balance - A Review of the Art. Part II. Advanced Concepts.”
International Journal of Microwave and Millimeter-wave Computer-Aided
Engineering, Volume 1, No. 2, pages 159-180, 1991.
[4] V. Rizzoli, F. Mastri, F. Sgallari, G. Spaletta, “Harmonic-Balance Simulation
of Strongly Nonlinear Very Large-Size Microwave Circuits by Inexact
Newton Methods,” MTT-S Digest, pages 1357-1360, 1996.
[5] S. Skaggs, Efficient Harmonic Balance Modeling of Large Microwave
Circuits, Ph.D. thesis, North Carolina State University, 1999.
[6] R.S. Carson, High-Frequency Amplifiers, 2nd Edition, John Wiley & Sons,
1982
[7] S.Y. Liao, Microwave Circuit Analysis and Amplifier Design, Prentice-Hall,
1987.
[8] J. Roychowdhury, D. Long, P. Feldmann, “Cyclostationary Noise Analysis of
Large RF Circuits with Multitone Excitations”, IEEE JSCC, volume 33,
number 3, March 1998.
[9] Y. Saad, Iterative Methods for Sparse Linear Systems, PWS Publishing
Company, 1995.
[10] J. Roychowdhury, D. Long, and P. Feldmann, “Cyclostationary Noise
Analysis of Large RF Circuits with Multitone Excitations,” IEEE Journal of
Solid-State Circuits, volume 33, pages 324–336, March 1998.
[11] K. Kurakawa, “Power waves and the Scattering Matrix,” IEEE Trans.
Microwave Theory Tech., vol. MTT-13, pp. 194-202, March 1965.
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Steady-State Shooting Newton Analysis
6
Describes HSPICE RF steady-state time domain analysis based on a
Shooting-Newton algorithm.
These topics are covered in the following sections:
■
SN Steady-State Time Domain Analysis
■
SN Analysis Syntax
■
SN Analysis Output
■
Shooting Newton with Fourier Transform (.SNFT)
SN Steady-State Time Domain Analysis
An advanced Shooting Newton (SN) algorithm provides additional performance
and functionality to HSPICE RF for time-domain, steady-state analysis.
Shooting-Newton adds analysis capabilities for PLL components, digital
circuits/logic, such as ring oscillators, frequency dividers, phase/frequency
detectors (PFDs), and for other digital logic circuits and RF components that
require steady-state analysis, but operate with waveforms that are more square
wave than sinusoidal.
The Shooting-Newton algorithm effectively analyzes applications including:
■
Ring oscillators (see Chapter 7, Oscillator and Phase Noise Analysis)
■
Frequency dividers (prescalers)
■
Mixer conversion gain
■
Phase-frequency detectors (PFDs)
■
Mixer noise figure
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SN Analysis Syntax
Functionality includes:
■
Both driven and oscillator (autonomous) analyses
■
Time Domain or Frequency analysis based on advanced Shooting Newton
algorithm
■
Spectrum analysis specific to the SN analysis (see Shooting Newton with
Fourier Transform (.SNFT) on page 137)
■
Shooting Newton-based AC analysis (SNAC) (see Shooting Newton AC
Analysis (.SNAC) on page 195)
■
Shooting Newton-based noise analysis (SNNOISE) (see Oscillator Analysis
Using Shooting Newton (.SNOSC) on page 158)
■
Shooting Newton-based phase noise analysis (PHASENOISE) (see
Oscillator and Phase Noise Analysis on page 143)
SN Analysis Syntax
Shooting Newton provides two syntaxes. Syntax #1 is recommended when you
are using/making Time Domain sources and measurements (for example,
going from .TRAN to .SN). Syntax #2 effectively supports Frequency Domain
sources and measurements (and should be used, for example, when going
from .HB to .SN).
Syntax #1
.SN TRES=Tr PERIOD=T [TRINIT=Ti]
+ [SWEEP parameter_sweep] [MAXTRINITCYCLES=integer]
or, Syntax #2
.SN TONE=F1 NHARMS=N [TRINIT=Ti]
+ [SWEEP parameter_sweep] [MAXTRINITCYCLES=integer]
where
132
Parameter
Description
TRES
The time resolution to be computed for the steady-state
waveforms (in seconds).
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SN Analysis Syntax
Parameter
Description
PERIOD
The expected period T (seconds) of the steady-state
waveforms. Enter an approximate value when using for
oscillator analysis. The period of the steady-state waveform
may be entered either as PERIOD or its reciprocal, TONE.
TONE
The fundamental frequency (in Hz).
NHARMS
Specifies the number of high-frequency harmonic
components to include in the analysis. NHARMS defaults to
PERIOD/TRES rounded to nearest integer. NHARMS is
required to run subsequent SNAC, SNNOISE, SNXF, and
PHASENOISE analyses. When using Syntax #1, NHARMS is
computed automatically as NHARMS=Round(PERIOD/
TRES).
TRINIT
This is the transient initialization time. If not specified, the
transient initialization time will be equal to the period (for
Syntax 1) or the reciprocal of the tone (for Syntax 2).
SWEEP
Specifies the parameter sweep. As in all main analyses in
HSPICE RF such as .TRAN, .HB, etc., you can specify LIN,
DEC, OCT, POI, SWEEPBLOCK, DATA, MONTE, or
OPTIMIZE.
MAXTRINITCYCLES
Stops SN stabilization simulation and frequency detection
when the simulator detects that maxtrinitcycles have been
reached in the oscnode signal, or when time=trinit, whichever
comes first. Minimum cycles is 1.
Options
In addition to all .TRAN options, .SN analysis supports the following options.
Option
Default Description
.OPTION SNMAXITER |
SN_MAXITER=integer
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SN Analysis Output
Option
Default Description
.OPTION SNCONTINUE= 1|2
1
Specifies whether to use the sweep
solution from the previous simulation as
the initial guess for the present
simulation.
■
■
.OPTION SNACCURACY=integer
10
SNCONTINUE=1 (default): Use
solution from previous simulation as
the initial guess.
HBCONTINUE=0: Start each
simulation in a sweep from the DC
solution.
Similar to the sim_accuracy definition
in.TRAN, i.e., larger values of
snaccuracy result in a more accurate
solution but may require more time
points. Because Shooting-Newton
must store derivative information at
every time point, the memory
requirements may be significant if the
number of time points is very large.
The maximum integer value is 50.
.OPTION LOADSNINIT=”filename”
Loads the operating point saved at the
end of SN initialization which is used as
initial conditions for the ShootingNewton method.
.OPTION SAVESNINIT=”filename”
Saves the operating point at the end of
SN initialization (sninit).
SN Analysis Output
The output from .SN analysis is generated in both time and frequency domains.
The time domain output variables are the same as for standard transient
analysis:
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SN Analysis Output
■
individual nodal voltages: V(n1 [,n2])
■
branch currents: I(Vxx)
■
element power dissipation: In(element)
It is also possible to output the results from Shooting Newton analysis in terms
of complex, frequency-domain output variables. This output format is activated
by using the “SNFD” keyword in the output syntax.
For output in the frequency domain, the syntax is identical to the Harmonic
Balance output syntax:
.PRINT SNFD TYPE(NODES | ELEM)[INDICES]
.PROBE SNFD TYPE(NODES | ELEM)[INDICES]
Parameter Description
TYPE Specifies a harmonic type node or element. TYPE can be one of the
following:
■
Voltage type –
■
V = voltage magnitude and phase in degrees
■
VR = real component
■
VI = imaginary component
■
VM = magnitude
■
VP - Phase in degrees
■
VPD - Phase in degrees
■
VPR - Phase in radians
■
VDB - dB units
■
VDBM - dB relative to 1 mV
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SN Analysis Output
■
Current type –
■
I = current magnitude and phase in degrees
■
IR = real component
■
II = imaginary component
■
IM = magnitude
■
IP - Phase in degrees
■
IPD - Phase in degrees
■
IPR - Phase in radians
■
IDB - dB units
■
IDBM - dB relative to 1 mV
■
Power type – P
■
Frequency type –
■
hertz[index], hertz[index1, index2, ...]
You must specify the harmonic index for the hertz variable. The frequency of
the specified harmonics is dumped.
Parameter Description
NODES | ELEM can be any of the following:
■
Voltage type – a single node name (n1), or a pair of node names, (n1,n2)
■
Current type – an element name (elemname)
■
Power type – a resistor (resistorname) or port (portname) element name
■
INDEX n1, is the harmonic index of the SNFD tone. Index is limited to the
single tone associated with the SN analysis.
Output Files
The time domain data are output to printsn0 and .sn0 files. Frequency domain
data are output to .printsnf0 and .snf0 files.
Output Format
The format for time domain output is the same as standard transient analysis.
For frequency domain output, the format is similar to HB. The main difference is
that Shooting Newton output in the frequency domain is single tone only.
The results of an SN analysis are complex spectral components at each
frequency point. The a[i] is the real part, and b[i] is the imaginary part of the
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Shooting Newton with Fourier Transform (.SNFT)
complex voltage at frequency index i. The conversion to a steady state timedomain is then given by the Fourier series expansion.
An SN analysis produces these output data files:
■
Output from the .PRINT SN statement is written to a .printsn# file.
•
The header contains the large signal fundamental frequencies.
•
The columns of data are labeled as HERTZ, followed by frequency
indices, and then the output variable names.
•
The sum of the frequency indices, multiplied by the corresponding
fundamental frequencies, add up to the frequency in the first column.
■
Output from the .PROBE SN statement is written to a .sn# file in the same
format as the HSPICE transient analysis .tr# file. It contains the information
of harmonic indices and basic tone frequencies plus the output waveform.
■
Reported performance log statistics are written to a .lis file:
•
Name of SN data file.
•
Simulation time:
DC operating point (op) time
SN time
Total simulation time
•
Memory used
•
Size of matrix (nodes * harmonics)
•
Final SN residual error
Shooting Newton with Fourier Transform (.SNFT)
The .SNFT command is to the .SN analysis what .FFT is to the TRAN analysis,
a means to provide spectrum analysis. Spectrum analysis represents a timedomain signal, within the frequency domain. .SNFT uses the Fourier transform:
a Discrete Fourier Transform (DFT) uses sequences of time values to
determine the frequency content of analog signals, in circuit simulation.
The .SNFT statement uses the internal time point values.
By default, the .SNFT statement uses a second-order interpolation to obtain
waveform samples, based on the number of points that you specify.
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Shooting Newton with Fourier Transform (.SNFT)
You can use windowing functions to reduce the effects of waveform truncation
on the spectral content. You can also use the .SNFT command to specify:
■
output format
■
frequency
■
number of harmonics
■
total harmonic distortion (THD)
.SNFT Input Syntax
The .SNFT command an take arguments with either alphanumeric or numerics
and expressions.
Syntax # 1 Alphanumeric input
.SNFT output_var [START=val] [STOP=val]
+ [NP=value] [FORMAT=keyword]
+ [WINDOW=keyword] [ALFA=val]
+ [FREQ=val] [FMIN=val] [FMAX=val]
Syntax #2 Numerics and expressions
.SNFT output_var [START=param_expr1] [STOP=param_expr2]
+ [NP=param_expr3] [FORMAT=keyword]
+ [WINDOW=keyword] [ALFA=param_expr4]
+ [FREQ=param_expr5] [FMIN=param_expr6] [FMAX=param_expr7]
Arguments
138
Argument
Description
output_var
Can be any valid output variable, such as voltage, current, or power.
START
Start of the output variable waveform to analyze. Defaults to the START
value in the .SN statement, which defaults to 0.
FROM
An alias for START in .SNFT statements.
STOP
End of the output variable waveform to analyze. Defaults to the TSTOP
value in the .SN statement.
TO
An alias for STOP, in .SNFT statements.
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Shooting Newton with Fourier Transform (.SNFT)
Argument
Description
NP
Number of points to use in the SNFT analysis. NP must be a power of
2. If NP is not a power of 2, HSPICE automatically adjusts it to the
closest higher number that is a power of 2. The default is 1024.
FORMAT
Specifies the output format:
■
■
WINDOW
Specifies the window type to use:
■
■
■
■
■
■
■
■
ALFA
NORM= normalized magnitude (default)
UNORM=unnormalized magnitude
RECT=simple rectangular truncation window (default).
BART=Bartlett (triangular) window.
HANN=Hanning window.
HAMM=Hamming window.
BLACK=Blackman window.
HARRIS=Blackman-Harris window.
GAUSS=Gaussian window.
KAISER=Kaiser-Bessel window.
Parameter to use in GAUSS and KAISER windows to control the
highest side-lobe level, bandwidth, and so on.
1.0 <= ALFA <= 20.0
The default is 3.0
FREQ
Frequency to analyze. If FREQ is non-zero, the output lists only the
harmonics of this frequency, based on FMIN and FMAX. HSPICE also
prints the THD for these harmonics. The default is 0.0 (Hz).
FMIN
Minimum frequency for which HSPICE prints SNFT output into the
listing file. THD calculations also use this frequency.
T=(STOP-START)
The default is 1.0/T (Hz).
FMAX
Maximum frequency for which HSPICE prints SNFT output into the
listing file. THD calculations also use this frequency. The default is
0.5*NP*FM IN (Hz).
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Shooting Newton with Fourier Transform (.SNFT)
Example 1
.SNFT v(1)
.SNFT v(1,2) np=1024 start=0.3m stop=0.5m freq=5.0k
+ window=kaiser alfa=2.5
.SNFT I(rload) start=0m to=2.0m fmin=100k fmax=120k
+ format=unorm
.SNFT par(‘v(1) + v(2)’) from=0.2u stop=1.2u
+ window=harris
Example 2
.SNFT v(1) np=1024
.SNFT v(2) np=1024
This example generates an .snft0 file for the SNFT of v(1) and an .snft1 file for
the SNFT of v(2).
.SN Signal Sources
.SN analysis assumes that all stimuli are periodic with period T. If the circuit is
driven with more than one periodic stimulus, then the frequencies must be all
co-periodic and T must match the common period or some integer multiple of it.
The .SN analysis only supports .tran (time-domain) periodic signal sources.
(Refer to the .tran analysis for a detailed documentation on transient signal
sources).
.SN Reported Performance Log Statistics
The following performance statistics are displayed:
140
■
DC operating time
■
Initial transient time (including user's time for circuit stabilization)
■
Total simulation time
■
SN time
■
Total simulation time
■
Memory used
■
Final SN convergence residual error
■
The value of the computed frequency if the circuit is autonomous
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Shooting Newton with Fourier Transform (.SNFT)
Errors/Warnings
Error messages are displayed with convergence recommendations in cases of
non-convergence within the maximum number of Shooting-Newton iterations.
Error messages are displayed for software errors such as segmentation
violations, and abort conditions such as:
■
unrecognized format, i.e., unrecognized V/I source
■
faulty input values, i.e., wrong sign, out of range value
■
unspecified values, i.e., unspecified tone
■
inconsistent values, i.e., non-commensurable tones
■
duplicate values, i.e., same entry, given more than one, the last one is
always taken
Limitations and Assumptions
True distributed components (such as ideal delays or transmission lines) are
not supported; components with hidden states are not supported.
Example
For a demonstration of using Shooting Newton analysis you can run the
pdfcpGain.sp file shipped with the HSPICE RF distribution, located in the
directory $installdir/hspicerf/examples. This example performs analysis on a Dflipflop phase frequency divider with charge pump, implemented in 50nm
technology. The example is configured to measure the gain (volts per degree)
of the DFF PFD and tri-state output combination.
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Chapter 6: Steady-State Shooting Newton Analysis
Shooting Newton with Fourier Transform (.SNFT)
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7
Oscillator and Phase Noise Analysis
7
Describes how to use HSPICE RF to perform oscillator and phase noise
analysis on oscillator circuits.
These topics are covered in the following sections:
■
Harmonic Balance or Shooting Newton for Oscillator Analysis
■
Harmonic Balance Oscillator Analysis (.HBOSC)
■
Input Syntax for Harmonic Balance Oscillator Analysis
■
HB Simulation of Ring Oscillators
■
HBOSC Analysis Using Transient Initialization
■
Oscillator Analysis Using Shooting Newton (.SNOSC)
■
Phase Noise Analysis (.PHASENOISE)
■
Accumulated Jitter Measurement for Closed Loop PLL Analysis
■
Small-Signal Phase-Domain Noise Analysis (.ACPHASENOISE)
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Chapter 7: Oscillator and Phase Noise Analysis
Harmonic Balance or Shooting Newton for Oscillator Analysis
Harmonic Balance or Shooting Newton for Oscillator
Analysis
Oscillator Classification
Oscillators can be divided into two main categories:
1. Ring oscillators: These oscillators tend to have low Q and operate based on
delay of digital cells such as inverters. Ring oscillators have strong nonlinear
behavior and output signals are often square-wave-like. Ring oscillators can
be analyzed in either the frequency domain using Harmonic Balance
analysis or in the time domain using Shooting Newton analysis.
2. Harmonic oscillators: Common harmonic oscillators are LC and crystal
oscillators. These oscillators tend to have a high Q, making it difficult to find
the oscillation frequency. Their behavior tends to be only mildly nonlinear
and their output signals tend to be close to purely sinusoidal. Harmonic
Balance analysis is most effective for analyzing harmonic oscillators.
HSPICE RF includes special analysis algorithms for finding the steady-state
solution for oscillator circuits. In oscillators, there are no driving sources that set
the frequencies of operation, but rather the fundamental oscillation frequency is
one of the unknowns that is being solved by the simulator. HSPICE RF
provides two approaches: either harmonic balance or analysis based on the
Shooting Newton algorithm.
The following sections are presented in this chapter:
■
Harmonic Balance Oscillator Analysis (.HBOSC)
■
Oscillator Analysis Using Shooting Newton (.SNOSC)
■
Phase Noise Analysis (.PHASENOISE)
Harmonic Balance Oscillator Analysis (.HBOSC)
Because the frequency of oscillation is not determined by the frequencies of
driving sources, a slightly different set of nonlinear equations are solved during
the simulation and are as shown in the following equation:
Equation 24
144
F ( V, ω0 ) = I ( V, ω0 ) + ΩQ ( V, ω0 ) + Y ( ω0 )V + I s
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Chapter 7: Oscillator and Phase Noise Analysis
Harmonic Balance Oscillator Analysis (.HBOSC)
HSPICE harmonic balance oscillator analysis (.HBOSC) adds the fundamental
frequency of oscillation to the list of unknown circuit quantities. To
accommodate the extra unknown, the phase (or equivalently, the imaginary
part) of one unknown variable (generally a node voltage) is set to zero. The
phases of all circuit quantities are relative to the phase, at this reference node
(referred to as the “PROBENODE”).
Additionally, the HBOSC analysis tries to avoid the “degenerate solution,”
where all non-DC quantities are zero. Although this is a valid solution of the
above equation (it is the correct solution, if the circuit does not oscillate),
HBOSC analysis might find this solution incorrectly, if the algorithm starts from
a bad initial solution.
The HBOSC analysis follows a technique similar to that described by Ngoya, et
al, which uses an internally-applied voltage probe to find the oscillation voltage
and frequency. The source resistance of this probe is a short circuit at the
oscillation frequency, and an open circuit otherwise. HSPICE RF uses a twotier Newton approach to find a non-zero probe voltage, which results in zero
probe current.
The DC solution is used as a starting point for the HB analysis of the oscillator
circuit. In addition to the DC solution, initial values for both the oscillation
frequency and the probe voltage are needed. HBOSC analysis calculates the
small-signal admittance that the voltage probe sees over a range of
frequencies in an attempt to find potential oscillation frequencies. Oscillation is
likely to occur where the real part of the probe current is negative, and the
imaginary part is zero. You can use the FSPTS parameter to specify the
frequency search. You must also supply an initial guess for the large signal
probe voltage. A value of one-half the supply voltage is often a good starting
point.
Input Syntax for Harmonic Balance Oscillator Analysis
The input syntax for HBOSC analysis supports two different formats,
depending on whether the PROBENODE location is specified using a circuit
element (current source) or using the HBOSC PROBENODE parameters:
Syntax #1
.HBOSC TONE=F1 NHARMS=H1
+ PROBENODE=N1,N2,VP
+[FSPTS=NUM, MIN, MAX] [STABILITY=(-2|-1|0|1|2)]
+[SWEEP PARAMETER_SWEEP] [SUBHARMS=I]
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Harmonic Balance Oscillator Analysis (.HBOSC)
Syntax #2 (Uses current source to set PROBENODE)
ISRC N1 N2 HBOSCVPROBE=VP
.HBOSC TONE=F1 NHARMS=H1
+[FSPTS=NUM, MIN, MAX] [STABILITY=(-2|-1|0|1|2)]
+[SWEEP PARAMETER_SWEEP] [SUBHARMS=I]
Parameter
Description
TONE
Approximate value for oscillation frequency (Hz). The search for an exact
oscillation frequency begins from this value, unless you specify an FSPTS
range or transient initialization (see HB Simulation of Ring Oscillators on
page 150 for more information).
NHARMS
Number of harmonics to use for oscillator HB analysis.
PROBENODE
Circuit nodes that are probed for oscillation conditions.
■
■
N1 and N2 are the positive and negative nodes for a voltage probe
inserted in the circuit to search for oscillation conditions.
VP is the initial probe voltage value (one-half the supply voltage is a
suggested value).
The phase of the probe voltage is forced to zero; all other phases are relative
to the probe phase. HSPICE RF uses this probe to calculate small-signal
admittance for the initial frequency estimates. It should be connected near
the “heart” of the oscillator (near resonators, inside the ring of a ring
oscillator, etc.).
Note: The PROBENODE pins and approximate voltage value can also be set
by using a zero amp current source that uses the HBOSCVPROBE keyword.
HBOSCVPROBE= Sets PROBENODE parameters with a separate current source element. If a
VP
current source with HBOSCVPROBE is used, the PROBENODE parameter
and its values need not be included in the .HBOSC command.
FSPTS
Specifies the frequency search points that HSPICE RF uses in its initial
small-signal frequency search to find an oscillation frequency. Optional, but
recommended for high-Q and most LC oscillators. If the circuit is a ring
oscillator, see HB Simulation of Ring Oscillators on page 150 for more
information on how to use the HBTRANINIT option.
■
■
NUM is an integer.
MIN and MAX are frequency values in units of Hz.
If the FSPTS analysis finds an approximate oscillation frequency, the TONE
parameter may be ignored.
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Chapter 7: Oscillator and Phase Noise Analysis
Harmonic Balance Oscillator Analysis (.HBOSC)
Parameter
Description
STABILITY
When used with FSPTS, activates the additional oscillator stability analyses
depending on the following values:
■
■
■
■
■
0: A single point oscillator frequency-search stability analysis is
performed. The FSPTS search is executed, and the first successful linear
oscillation frequency value found is used as the starting point for the twotier Newton nonlinear oscillator analysis. The probenode vp value
specified is used as the starting amplitude for the Newton solver.
1: (default) A single point oscillator frequency-search stability analysis,
plus an estimate of oscillator amplitude, is performed. The FSPTS search
is executed, and the first successful linear oscillation frequency value
found is used as the starting point for the two-tier Newton nonlinear
oscillator analysis. An additional analysis for automatically estimating the
probenode amplitude is also performed, and this value is used as the
starting amplitude for the two-tier Newton solver.
–1: A single point oscillator frequency-search stability analysis, plus an
estimate of oscillator amplitude, is performed. The FSPTS search is
executed, and the first successful linear oscillation frequency value found
is accurately computed and reported. An additional analysis for
automatically estimating the probenode amplitude is also performed, and
this value is also reported. The analysis aborts without attempting the
two-tier Newton nonlinear oscillator analysis. By using STABILITY=–1, a
check can be made if any linear oscillation conditions are found, before
attempting the nonlinear oscillator analysis.
2: A multi-point frequency-search stability analysis is performed. The
FSPTS search is executed, and all successful linear oscillation frequency
values found over the entire FSPTS search range are reported. For each
potential oscillation frequency found, an additional analysis for estimating
the probenode amplitude is also performed. All frequency and amplitude
values are reported. The frequency value that has the largest predicted
amplitude is used as the starting point for the two-tier Newton nonlinear
oscillator analysis.
–2: A multi-point frequency-search stability analysis is performed. The
FSPTS search is executed, and all successful linear oscillation frequency
values found over the entire FSPTS search range are reported. For each
potential oscillation frequency found, an additional analysis for estimating
the probenode amplitude is also performed. All frequency and amplitude
values are reported. The analysis aborts without attempting the two-tier
Newton nonlinear oscillator analysis. By using STABILITY=–2, a check
can be made if any linear oscillation conditions are found, before
attempting the nonlinear oscillator analysis.
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Harmonic Balance Oscillator Analysis (.HBOSC)
Parameter
Description
SWEEP
Specifies the type of sweep. You can sweep up to three variables. You can
specify either LIN, DEC, OCT, POI, SWEEPBLOCK, DATA, OPTIMIZE, or
MONTE. Specify the nsteps, start, and stop frequencies using the following
syntax for each type of sweep:
■
■
■
■
■
■
■
■
SUBHARMS
LIN nsteps start stop
DEC nsteps start stop
OCT nsteps start stop
POI nsteps freq_values
SWEEPBLOCK nsteps freq1 freq2 ... freqn
DATA=dataname
OPTIMIZE=OPTxxx
MONTE=val
Allows subharmonics in the analysis spectrum. The minimum non-DC
frequency in the analysis spectrum is f/subharms, where f is the frequency
of oscillation. Use this option if your oscillator circuit includes a divider or
prescaler that will result in frequency terms that are subharmonics of the
fundamental oscillation frequency
Note:
You can specify either .OPTION HBTRANPTS or .OPTION
HBTRANSTEP, but not both.
Simulation Strategies for Harmonic Oscillators
Since harmonic oscillators tend to have high Q, they are more sensitive than
ring oscillators to frequency and amplitude guess. The high Q also means that
HBTRANINIT is not usually helpful, because it takes too long for transient
simulation to settle close enough to steady state. For these oscillators, FSPTS
tends to work well, because the behavior is close to linear.
The recommended setup for harmonic oscillators is:
148
■
Set up .HBOSC with FSPTS. Higher Q oscillators may need more FSPTS
points.
■
Choose a node directly connected to the oscillator or crystal as the
PROBENODE.
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Chapter 7: Oscillator and Phase Noise Analysis
Harmonic Balance Oscillator Analysis (.HBOSC)
■
The number of harmonics specified by nharms can be fairly small, perhaps
10, unless some digital circuitry is included in the simulation.
■
Do not use HBTRANINIT.
Because the challenges related to ring oscillators and harmonic oscillators
are so different, we approach them with separate simulation strategies.
.HBOSC Examples
Example 1
.HBOSC tone=900MEG nharms=9 probenode=gate,gnd,0.65
Performs an oscillator analysis, searching for frequencies in the vicinity of 900
MHz. This example uses nine harmonics with the probe inserted between the
gate and gnd nodes. The probe voltage estimate is 0.65 V.
Example 2
.HBOSC tone=2400MEG nharms=11
+ probenode=drainP,drainN,1.0 fspts=20,2100MEG,2700MEG
Performs an oscillator analysis, searching for frequencies in the vicinity of 2.4
GHz. This example uses 11 harmonics with the probe inserted between the
drainP and drainN nodes. The probe voltage estimate is 1.0 V.
Example 3
Another means to define the probenode information is through a zero-current
source. The following two methods define an equivalent .HBOSC command:
■
Method 1:
.HBOSC tone = 2.4G nharms = 10
+ probenode = drainP, drainN, 1.0
+ fspts = 20, 2.1G, 2.7G
■
Method 2:
ISRC drainP drainN 0 HBOSCVPROBE = 1.0
.HBOSC tone = 2.4G nharms = 10
+ fspts = 20, 2.1G, 2.7G
In Method 2, the PROBENODE information is defined by a current source in the
circuit. Only one such current source is needed, and its current must be 0.0
with the HBOSC PROBENODE voltage defined through its HBOSCVPROBE
property.
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Chapter 7: Oscillator and Phase Noise Analysis
Harmonic Balance Oscillator Analysis (.HBOSC)
HB Simulation of Ring Oscillators
Ring oscillators require a slightly different simulation approach in HB. Since
their oscillation is due to the inherent delay in the inverters of the ring, they are
best modeled in the time domain and not in the frequency domain.
In addition, ring oscillator waveforms frequently approach square waves, which
require a large number of harmonics to be described in the frequency domain.
An accurate initial guess is important if they are going to be simulated
accurately with HB.
The HSPICE RF HBOSC analysis typically starts from the DC solution and
looks for potential resonances in the linear portion of the circuit to determine
the initial guess for the oscillation frequency. However, these resonances
generally do not exist in ring oscillators, which do not contain linear resonant
elements.
HB analysis provides a second method of obtaining a good initial guess for the
oscillation frequency, which is specifically intended for ring oscillators. Instead
of starting from the results of a DC analysis, this method starts from the result
of a transient analysis. This method is called Transient Initialization and also
provides a good initial guess for all the voltages and currents in the circuit.
The recommended setup for ring oscillators is therefore:
150
■
Set up .HBOSC without FSPTS.
■
Choose one of the nodes in the ring as the PROBENODE.
■
Since ring oscillators tend to have square-wave-like output signals which
have significant high frequency content, a relatively large value, perhaps 50,
for nharms is recommended. Ring oscillators with more stages tend to need
more harmonics.
■
Set HBTRANINIT to a value that represents ~5-10 oscillator periods, and
make sure that you include an .ic command or other transient analysis setup
to start the oscillator in transient simulation. Longer HBTRANINIT times may
result in faster HBOSC convergence, at the expense of additional CPU time
spent on HBTRANINIT.
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HBOSC Analysis Using Transient Initialization
HBOSC Analysis Using Transient Initialization
To perform an HBOSC analysis, use the following options in your HSPICE RF
netlist.
Table 7
HBOSC Analysis Options for Transient Initialization
Keyword
Description
HBTRANINIT = time
Tells HB to use transient analysis to initialize all
state variables. time is when the circuit has
reached (or is near) steady-state. Default = 0.
HBTRANPTS = npts
npts specifies the number of points per period for
converting the time-domain data results from
transient analysis, into the frequency domain.
npts must be an integer greater than 0. The units
are in nharms (nh). Default=4*nh.
This option is relevant only if you set .OPTION
HBTRANINIT.
HBTRANSTEP = stepsize
stepsize specifies the step size for the transient
analysis.
The default is 1/(4*nh*f0), where nh is the
nharms value and f0 is the oscillation frequency.
This option is relevant only if you set .OPTION
HBTRANINIT.
HBTRANFREQSEARCH = 1|0
If HBTRANFREQSEARCH=1 (default), then HB
analysis calculates the oscillation frequency
from the transient analysis.
Otherwise, HB analysis assumes that the period
is 1/f, where f is the frequency specified in the
tones description.
You must also either specify the initial conditions or add a PWL or PULSE
source to start the oscillator for transient analysis. This source should provide a
brief stimulus, and then return to zero. HB analysis effectively ignores this type
of source, treating it as zero-valued.
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Chapter 7: Oscillator and Phase Noise Analysis
HBOSC Analysis Using Transient Initialization
This method does the following:
1. If HBTRANFREQSEARCH=1, transient analysis runs for several periods,
attempting to determine the oscillation frequency from the probe voltage
signal.
2. Transient analysis continues until the time specified in HBTRANINIT.
3. Stores the values of all state variables over the last period of the transient
analysis.
4. Transforms the state variables to the frequency domain by using a Fast
Fourier Transform (FFT) to establish an initial guess for HB oscillator
analysis.
5. Starts the standard HB oscillator analysis.
Additional .HBOSC Analysis Options
Oscillator analysis will make use of all standard HB analysis options as listed in
the following table. In addition, the following options are specifically for
oscillator applications.
Table 8
152
HBOSC Analysis Options for Oscillator Applications
Parameter
Description
HBFREQABSTOL
An additional convergence criterion for oscillator analysis.
HBFREQABSTOL is the maximum absolute change in
frequency between solver iterations for convergence.
Default is 1 Hz.
HBFREQRELTOL
An additional convergence criterion for oscillator analysis.
HBFREQRELTOL is the maximum relative change in
frequency between solver iterations for convergence.
Default is 1.e-9.
HBPROBETOL
HBOSC analysis tries to find a probe voltage at which the
probe current is less than HBPROBETOL. This option
defaults to the value of HBTOL, which defaults to 1.e-9.
HBOSCMAXITER (or
HBOSC_MAXITER)
Maximum number of outer-loop iterations for HBOSC
analysis. It defaults to 10000.
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Chapter 7: Oscillator and Phase Noise Analysis
HBOSC Analysis Using Transient Initialization
.HBOSC Output Syntax
The output syntax for .HBOSC analysis is identical to that for HB analysis (see
Chapter 5, Steady-State Harmonic Balance Analysis). To output the final
frequency of oscillation, use the HERTZ keyword. For example, HERTZ[1]
identifies the fundamental frequency of oscillation.
Note:
For PROBENODE = n1 n2 vp, where vp is a voltage, units must
be given in volts.
See also Outputting Phase Noise Source as ASCII Data Files Using *.printpn0.
Troubleshooting Convergence Problems
This section lists the most common causes of convergence problems, how to
recognize them, and resolve them.
The HSPICE RF harmonic balance oscillator analysis is a two-tier iterative
analysis, consisting of “inner loop” and “outer loop” iterations. In the outer loop
iteration, HBOSC will iterate to reduce the “probe error” which is reported for
each outer loop iteration. Each outer loop iteration involves a non-autonomous
Harmonic Balance (HB) circuit solution; this non-autonomous solve is referred
to as the inner loop iteration.
If HBOSC has inner loop convergence problems, the simulation may get stuck
on the first outer loop iteration or you may see warning messages such as:
Warning: HB_WARN.3: Final HB residual value > HB_TOL.
Rank of HB Jacobian = 155
Warning: HB_WARN.3: HB convergence failure in non-autonomous HB.
For each outer loop iteration, the probe voltage and probe frequency are listed.
If an outer loop convergence problem occurs, you may see the following:
■
Decreasing probe voltage values.
■
Wildly fluctuating values of probe frequency.
Osc probe : voltage = 0.218234 frequency =
6.240794122744832e+09
■
A warning message which indicates that the oscillator simulation has
reached a non-oscillating DC solution.
Warning: HB_ERR.18: HB oscillator analysis has reached the
NULL solution.
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HBOSC Analysis Using Transient Initialization
General Convergence Issues
Probe Node Location
Since convergence is sensitive to the probe node location, convergence
problems can often be tracked to this setting.
A common scenario is that the oscillator's output signal is passed through one
or more buffers, and the designer may think of the buffer output as the oscillator
output. A frequent mistake is to place the probe node at the output of the buffer,
but in fact, this will cause HB convergence problems. In this case, the probe
node should be moved to the oscillator part of the circuit. Often, it is necessary
to select an internal node of a subcircuit to achieve this.
The most typical symptom of this problem is inner loop convergence failure. As
mentioned above, for ring oscillators, always choose a node that is part of the
ring, i.e., connecting two stages of the ring; for harmonic oscillators, choose a
node close to the oscillator.
Incorrect Source Values
If the original netlist was set up to simulate the oscillator in transient analysis,
some voltage or current sources may have transient descriptions (e.g., PWL) in
order to start the oscillator. For example, a voltage supply may be ramped to
simulate a power-up to start the oscillator:
Vvdd vdd 0 PWL (0 0 1n 3)
In this case, the user would like HBOSC to use 3 as the voltage source value,
but HBOSC will use 0 because the explicit DC value of the source is used for
Harmonic Balance. HSPICE RF tries to interpret your sources intelligently but,
in some cases it may not be able to determine what you intended.
For the above example, there are a few ways to ensure that HSPICE RF
correctly interprets the source.
■
Remove the explicit DC value. If only a transient description is given, HB will
use the time=infinity value of the source.
■
Add TRANFORHB=1
Vvdd vdd 0 PWL (0 0 1n 3) TRANFORHB=1
The TRANFORHB=1 keyword will cause HB to use the transient analysis
description in HB and HBOSC.
■
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Add an explicit HB value
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HBOSC Analysis Using Transient Initialization
Vvdd vdd 0 PWL (0 0 1n 3) HB 3 0 0
This causes HB to treat the source as a 3V DC source (0th harmonic is
specified). If a HB value is given, HSPICE RF will ignore the PWL
description and use “HB 3 0 0” (amplitude=3, phase=0, harmonic=0)
instead. The PWL description will still be used for HBTRANINIT.
Incorrect source values usually result in the following:
■
High residual value after HBTRANINT. Usually, HBTRANINIT should
produce a good starting point for HB or HBOSC. Typical residuals after
HBTRANINIT are 1e-4 or 1e-5. If the initial residual printed immediately
after HBTRANINIT is done is high, there may be a source problem. In the
VDD ramping example above, you might see a residual value of 3.Outer
loop may converge to DC solution because incorrect source values result in
a non-oscillatory circuit:
Warning: HB_ER.18: HB oscillator analysis has reached the NULL
solution.
■
In some cases, inner loop non-convergence may occur.
GMRES Convergence
When the default value for .option HBSOLVER (=1) is set, HSPICE RF uses a
GMRES iterative solver to solve the linear systems that arise on each inner
loop Newton-Raphson step. If GMRES does not solve the linear systems
accurately enough, then the inner loop may not converge.
The GMRES solver is controlled by two options:
■
HBKRYLOVTOL: relative tolerance for GMRES solver. Default is 0.01, or
1%. For some circuits, setting this option will help inner loop convergence:
.option HBKRYLOVTOL=1e-3
■
HBKRYLOVDIM: dimension of Krylov subspace used in GMRES iteration.
Also controls maximum number of GMRES iterations. In HSPICE RF's .lis
file, the number of GMRES iterations taken for each Newton-Raphson step
is listed. If that number is equal to HBKRYLOVDIM, convergence may be
improved by increasing HBKRYLOVDIM. Example:
.option HBKRYLOVDIM=80
The symptom for GMRES convergence difficulty is always inner loop
convergence failure, or slow inner loop convergence. If this problem occurs, the
inner loop convergence is often good until the residual reaches a fairly low
value like 1e-8 or 1e-7, and then stagnates.
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HBOSC Analysis Using Transient Initialization
Accuracy of Initial Guess
Both inner loop and outer loop convergence improves significantly if the
starting point or initial guess of the iterative method is good.
Outer Loop Convergence
For outer loop convergence, the initial guess consists simply of the oscillation
frequency and first harmonic amplitude at the probe node location. If inner loop
convergence is successful but outer loop convergence is not, then a better
frequency or amplitude guess may be needed.
If HBTRANINIT is being used, then the accuracy of the initial guess can be
improved by one of the following methods:
■
Increase the HBTRANINIT time, simply by increasing the value of the
HBTRANINIT option.
■
Increase the HBTRANINIT accuracy. You can increase the transient
analysis accuracy by setting .option DELMAX or .option SIM_ACCURACY.
For example, you may set
.option SIM_ACCURACY=10 HBTOL=1e-8
Note that SIM_ACCURACY will simultaneously tighten transient and HB
accuracy tolerances. If you want HB accuracy to remain unaffected, you
may also want to set HBTOL as in the example above.
■
Increase accuracy of time domain to frequency domain conversion of
HBTRANINIT results, by increasing HBTRANPTS or equivalently,
decreasing HBTRANSTEP. For example:
.option HBTRANSTEP=1p
If FSPTS is being used, you can increase the number of points. Sometimes, it
is best to supply a guess manually by removing FSPTS and adjusting the
TONES value.
If HBTRANINIT is not used, you may be able to improve convergence by
manually adjusting the PROBENODE amplitude guess.
To evaluate the effectiveness of your option settings, look at the “probe error”
reported after the first outer loop iteration:
Iteration 1
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HBOSC Analysis Using Transient Initialization
Osc probe : voltage = 0.2 frequency = 5.980000000000000e+09
hb residual = 7.628260e-10
Rank of HB Jacobian = 9102
Probe error = 0.000154462
dv = -0.0411324 df =-2.30464430e+08
A smaller probe error value indicates a better initial guess.
Inner Loop Convergence
If inner loop convergence is a problem, it may be because the initial voltage
waveform values are not close to the solution. The only way to improve the
voltage values is by using HBTRANINIT. While this will not work well for
harmonic oscillators, it does work well for ring oscillators. You can improve the
accuracy of HBTRANINIT as described in the outer loop convergence section
above.
If the initial residual is large after HBTRANINIT, you may want to check to make
sure that the voltage and current sources are consistent between HB and
transient analysis.
Insufficient Number of Harmonics
If the number of harmonics specified is too small to represent the signals
present in the circuit, you may see either convergence problems in either the
inner or outer loop, or the solution may converge to an unreasonable frequency
value.
It is difficult to know when the number of harmonics is insufficient, but if
suspected, it is a simple experiment to increase the value of NHARMS. If
convergence was achieved and the number of harmonics is large enough, then
the magnitude of the spectral data for all signals should significantly decay with
increasing frequency. If the spectral data for node voltages has not decayed at
the highest harmonics included in the simulation, an increase in the value of
NHARMS is recommended.
Presence of Frequency Divider
If a frequency divider is present and not accounted for by the SUBHARMS
setting, convergence is not possible because the Harmonic Balance spectrum
does not include the necessary low frequency components. As a result, you will
encounter inner loop convergence failure. When debugging HBOSC
convergence problems, it is necessary to rule out the possibility of presence of
frequency dividers early in the process.
If a frequency divider is present, you can simulate the circuit if you set
SUBHARMS to the largest frequency division present in the circuit. If a
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Oscillator Analysis Using Shooting Newton (.SNOSC)
frequency divider is present, it is almost always necessary to use the
HBTRANINIT option to achieve convergence.
To get optimal performance, it is recommend that you set
.option HBSOLVER=2
This activates a hybrid time/frequency-domain preconditioner which is
particularly effective on frequency dividers.
Oscillator Analysis Using Shooting Newton (.SNOSC)
The analysis described in Chapter 6, Steady-State Shooting Newton Analysis
also provides a very effective means for finding the steady-state for oscillator
circuits.
Ring oscillators are best suited for time domain analysis using Shooting
Newton because they tend to:
■
have a low Q
■
operate based on digital delays
■
have strongly nonlinear behavior
■
output signals that are piece-wise-linear or square-wave-like
HBOSC is superior for sinusoidal waveforms. As with the Harmonic Balance
approach, the goal is to solve for the additional unknown oscillation frequency.
This is accomplished in Shooting Newton by considering the period of the
waveform as an additional unknown, and solving the boundary conditions at
the waveform endpoints that coincide with steady-state operation. As with
regular Shooting Newton analysis, input may be specified in terms of time or
frequency values.
Syntax #1
.SNOSC TONE=F1 NHARMS=H1 [TRINIT=Ti] OSCNODE=N1
+[MAXTRINITCYCLES=N][SWEEP PARAMETER_SWEEP]
Syntax #2
.SNOSC TRES=Tr PERIOD=Tp [TRINIT=Tr] OSCNODE=N1
+[MAXTRINITCYCLES=I] SWEEP PARAMETER_SWEEP
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Oscillator Analysis Using Shooting Newton (.SNOSC)
Parameter
Description
TONE
Approximate value for oscillation frequency (Hz). The search
for an exact oscillation frequency begins from this value.
NHARMS
Number of harmonics to be used for oscillator SN analysis.
OSCNODE
Node used to probe for oscillation conditions. This node is
automatically analyzed to search for periodic behavior near
the TONE or PERIOD value specified.
TRINIT
This the transient initialization time. If not specified, the
transient initialization time will be equal to the period (for
Syntax 1) or the reciprocal of the tone (for Syntax 2). For
oscillators, we recommend specifying a transient initialization
time since the default initialization time is usually too short to
effectively stabilize the circuit.
MAXTRINITCYCLES
Stops SN stabilization simulation and frequency detection
when the simulator detects that MAXTRINITCYCLES have
been reached in the oscnode signal, or when time=trinit,
whichever comes first. Minimum cycles is 1. The
MAXTRINITCYCLES parameter is optional.
TRES
TRES is the time resolution to be computed for the steadystate waveforms (in seconds). The period of the steady-state
waveform may be entered either as PERIOD or its reciprocal,
TONE.
PERIOD
PERIOD is the expected period T (seconds) of the steadystate waveforms. Enter an approximate value when using for
oscillator analysis.
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Oscillator Analysis Using Shooting Newton (.SNOSC)
Parameter
Description
SWEEP
Specifies the type of sweep. You can sweep up to three
variables. You can specify either LIN, DEC, OCT, POI,
SWEEPBLOCK, DATA, OPTIMIZE, or MONTE. SWEEP is an
optional parameter. Specify the nsteps, start, and stop
frequencies using the following syntax for each type of sweep:
■
■
■
■
■
■
■
■
LIN nsteps start stop
DEC nsteps start stop
OCT nsteps start stop
POI nsteps freq_values
SWEEPBLOCK nsteps freq1 freq2 ... freqn
DATA=dataname
OPTIMIZE=OPTxxx
MONTE=val
Example 1
.SNOSC tone=900MEG nharms=9 trinit=10n oscnode=gate
Performs an oscillator analysis, searching for periodic behavior after an initial
transient analysis of 10 ns. This example uses nine harmonics while searching
for an oscillation at the gate node.
Example 2
.SNOSC tone=2400MEG nharms=11 trinit=20n oscnode=drainP
Performs an oscillator analysis, searching for frequencies in the vicinity of 2.4
GHz. This example uses 11 harmonics and a search at the drainP.
.SNOSC Output Syntax
The output syntax for .SNOSC analysis is identical to that for SN analysis (see
Chapter 6, Steady-State Shooting Newton Analysis). To output the final
frequency of oscillation, use the HERTZ keyword. For example, HERTZ[1]
identifies the fundamental frequency of oscillation.
See also Using Noise Analysis Results as Input Noise Sources.
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Phase Noise Analysis (.PHASENOISE)
Phase Noise Analysis (.PHASENOISE)
The following topics are covered in this section:
■
Phase Noise Analysis Overview
■
Identifying Phase Noise Spurious Signals
■
PHASENOISE Input Syntax
■
Phase Noise Algorithms
■
PHASENOISE Output Syntax
■
Phase Noise Analysis Options
■
Measuring Phase Noise with .MEASURE PHASENOISE
■
Amplitude Modulation/Phase Modulation Separation
Phase Noise Analysis Overview
.PHASENOISE analysis is designed for use with autonomous oscillators.
Phase Noise analysis requires first running either harmonic balance (HBOSC)
or Shooting Newton (SNOSC) analysis, and then PHASENOISE analysis. The
PHASENOISE analysis itself is identical whether you run SNOSC or HBOSC.
Figure 19 on page 161 shows a simple free-running oscillator, which includes a
port with injected current.
+
in
v(t)
-
Figure 19
Oscillator with Injected Current
An ideal oscillator would be insensitive to perturbations with a fixed amplitude,
frequency, and phase represented by:
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Phase Noise Analysis (.PHASENOISE)
Equation 25
v ( t ) = A cos [ ω0 t + φ0 ]
A noisy oscillator has amplitude and phase fluctuations we can write as:
Equation 26
v ( t ) = A ( t ) cos [ ω0 t + φ( t ) ]
In the preceding equation:
■
A(t) is the time varying amplitude for the noisy oscillator.
■
φ( t ) is the time varying phase for the noisy oscillator.
■
ω0 is the frequency of oscillation.
In most applications, the phase noise is of particular interest, because it
represents frequency fluctuations about the fundamental, which you cannot
remove. These fluctuations are random processes, and are typically expressed
in terms of their power spectral density. For most oscillators, the phase noise is
a low-frequency modulation that creates sidebands in the oscillator’s spectrum,
about ω0 .
For example, the following equation represents a simple sinusoidal variation in
the phase:
Equation 27
v ( t ) = A cos [ ω0 t + θ p sin ωm t ]
■
θ p is the peak phase deviation, specified as θ p = Δω ⁄ ωm
■
Δω is the peak angular frequency deviation.
For θ p « 1 , the following equation approximates the output:
Equation 28
θp
⎧
⎫
v ( t ) = A ⎨ cos ( ω0 t ) – ----- [ cos ( ω0 + ωp ) t – cos ( ω0 + ωm ) t ] ⎬
2
⎩
⎭
That is, when the peak phase deviation is small, the result is frequency
components on each side of the fundamental with amplitude θ p ⁄ 2 .
The Single-Sideband Phase Noise L ( f m ) is the ratio of noise power to carrier
power in a 1Hz bandwidth, at offset ωm = 2πf m , which in this case can be
written as:
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Equation 29
V sb
L ( f m ) = ⎛ --------⎞
⎝ A⎠
2
2
2
θp
θrms
= ----------- = ---------------4
2
This model for oscillator noise shows that sidebands about the fundamental,
due to noise, are directly related to the spectrum of the phase fluctuations
θ ( t ) . The more general definition of phase noise relates it to the spectral
density of phase fluctuations, i.
θ p2
Equation 30 S ( ω ) = ------ = 2L ( f )
φ m
m
2
HSPICE RF uses several sophisticated analysis techniques for computing the
power spectrum of the phase variations to yield the phase noise response. This
information can be used to predict the spectrum of the oscillator about the
fundamental frequency, and also used to predict its random jitter
characteristics.
Any .PHASENOISE analysis will result in the calculation of a curve fit for a
power-law model according to:
Equation 31
⎧ a3 a2 a1
⎫
L ( f ) = 10 ⋅ log ⎨ -----3- + -----2- + ------ + a0 ⎬
f
f
⎩f
⎭
The coefficients a3 , a2 , a1 , and a0 are reported in the .lis file.
The .lis file includes a table which models the phase noise, including the
behavioral model fit and its fit error.
|-------------------------------------------------------------|
| L(f) = 10*log10( a3/f^(2+ef) + a2/f^2 + a1/f^(ef) + a0 ) dBc/Hz|
| a3 = 0.000000e+00
|
| a2 = 3.165111e-02
|
| a1 = 0.000000e+00
|
| a0 = 0.000000e+00
|
| ef = 1.000000e+00
|
| Average fit error = 1.6185e+00 dB
|
| Maximum fit error = 8.4862e+00 dB @ 1.0000e+07 Hz
|
Identifying Phase Noise Spurious Signals
Realistic phase noise responses include spurs. Spurs are contributions to the
phase noise that result from deterministic signals present within the circuit. In
most cases, the spurs are very small signals and do not interfere with the
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Phase Noise Analysis (.PHASENOISE)
steady-state operation of the oscillator, but do add energy to the output
spectrum of the oscillator. The energy that the spurs adds may need to be
included in jitter measurements. The phase noise spurs feature adds an
additional analysis option that can predict the spurious contributions to the
jitter.
To activate the new phase noise spur analysis, use the SPURIOUS keyword in
the .PHASENOISE command. An additional .HBAC analysis is performed that
predicts the spurious contributions to the phase noise.
A voltage or current source can be used to add spurious signals to an oscillator
circuit. The keyword SPUR identifies the spurious signal.
Syntax
Exxxx n1 n2 … [SPUR mag phase freq] … $ voltage spur
Gxxxx n1 n2 … [SPUR mag phase freq] … $ current spur
Where,
■
mag is the amplitude in volts or amps
■
phase is the phase in degrees
■
freq is the frequency in Hz
The source is equivalent to a steady-state sinusoidal source at the specified
amplitude, phase, and frequency values. It is only used for the spurious
analysis and is ignored by all other analyses. The SPUR keyword is can be
combined into a source used for other analyses. It is recommended, however,
that SPUR sources be added as separate sources.
PHASENOISE Input Syntax
.PHASENOISE output frequency_sweep [method=0|1|2]
+ [carrierindex=int] [listfreq=(frequencies|none|all)]
+ [listcount=val] [listfloor=val] [listsources=on|off]
+ [spurious=0|1]
164
Parameter
Description
output
An output node, pair of nodes, or 2-terminal element. HSPICE RF
references phase noise calculations to this node (or pair of nodes).
Specify a pair of nodes as V(n+,n-). If you specify only one node, V(n+),
then HSPICE RF assumes that the second node is ground. You can
also specify a 2-terminal element.
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Phase Noise Analysis (.PHASENOISE)
Parameter
Description
frequency_sweep
A sweep of type LIN, OCT, DEC, POI, or SWEEPBLOCK. Specify the
type, nsteps, and start and stop time for each sweep type, where:
■
■
■
■
type = Frequency sweep type, such as OCT, DEC, or LIN.
nsteps = Number of steps per decade or total number of steps.
start = Starting frequency.
stop = Ending frequency.
The four parameters determine the offset frequency sweep about the
carrier used for the phase noise analysis.
LIN type nsteps start stopOCT type nsteps start stopDEC type nsteps
start stopPOI type nsteps start stopSWEEPBLOCK freq1 freq2 ... freqn
method
■
■
■
METHOD=0 (default) selects the Nonlinear Perturbation (NLP)
algorithm, which is used for low-offset frequencies.
METHOD=1 selects the Periodic AC (PAC) algorithm, which is used
for high-offset frequencies.
METHOD=2 selects the Broadband Phase Noise (BPN) algorithm,
which you can use to span low and high offset frequencies.
You can use METHOD to specify any single method. See the section on
Phasenoise Algorithms below for a more detailed discussion on using
the METHOD parameter.
carrierindex
Optional. Specifies the harmonic index of the carrier at which HSPICE
RF computes the phase noise. The phase noise output is normalized to
this carrier harmonic. Default=1.
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Phase Noise Analysis (.PHASENOISE)
Parameter
Description
listfreq
Dumps the element phase noise value to the .lis file. You can specify
which frequencies the element phase noise value dumps. The
frequencies must match the sweep_frequency values defined in the
parameter_sweep, otherwise they are ignored.
In the element phase noise output, the elements that contribute the
largest phase noise are dumped first. The frequency values can be
specified with the NONE or ALL keyword, which either dumps no
frequencies or every frequency defined in the parameter_sweep.
Frequency values must be enclosed in parentheses. For example:
■
listfreq=(none)
listfreq=(all)
■
listfreq=(1.0G)
■
listfreq=(1.0G, 2.0G)
The default value is the first frequency value.
■
listcount
Dumps the element phase noise value to the .lis file, which is sorted
from the largest to smallest value. You do not need to dump every noise
element; instead, you can define listcount to dump the number of
element phase-noise frequencies. For example, listcount=5 means that
only the top 5 noise contributors are dumped. The default value is 20.
listfloor
Dumps the element phase noise value to the .lis file and defines a
minimum meaningful noise value (in dBc/Hz units). Only those
elements with phase-noise values larger than the listfloor value are
dumped. For example, listfloor=-200 means that all noise values below
-200 (dBc/Hz) are not dumped. The default value is -300 dBc/Hz.
listsources
Dumps the element phase-noise value to the .lis file. When the element
has multiple noise sources, such as a level 54 MOSFET, which contains
the thermal, shot, and 1/f noise sources. When dumping the element
phase-noise value, you can decide if you need to dump the contribution
from each noise source. You can specify either ON or OFF: ON dumps
the contribution from each noise source and OFF does not. The default
value is OFF.
spurious
Selects phase noise spur analysis
0 = No spurious analysis (default)
1 = Activates additional SPUR source analysis
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Phase Noise Analysis (.PHASENOISE)
Phase Noise Algorithms
HSPICE RF provides three algorithms for oscillator phasenoise: nonlinear
perturbation, periodic AC, and broadband calculations. These algorithms are
selected by setting the METHOD parameter to 0, 1, or 2, respectively.
Each algorithm has their regions of validity and computational efficiency, so
some thought is necessary to obtain meaningful results from a PHASENOISE
simulation. For each algorithm, the region of validity depends on the particular
circuit being simulated. However, there are some general rules that can be
applied to oscillator types (that is, ring or harmonic) so that a valid region can
be identified. And there are techniques that can be used to check validity of
your simulation results.
Nonlinear Perturbation Algorithm
The nonlinear perturbation (NLP) algorithm, which is the default selection, is
typically the fastest computation, but is valid only in a region close to the carrier.
Generally, you will want to use this algorithm if you interested in phasenoise
close to the carrier and do not need to determine a noise floor. NLP
computation time is almost independent of the number of frequency points in
the phasenoise frequency sweep.
Periodic AC Algorithm
The periodic AC (PAC) algorithm is valid in a region away from the carrier and is
slower than the NLP algorithm. The PAC algorithm is used for getting
phasenoise in the far carrier region and when you need to determine a noise
floor.
The computation time for the PAC algorithm is approximately linearly
dependent on the number of frequency points in the phasenoise frequency
sweep. If you are using the PAC algorithm, you should try to minimize the
number of points in the sweep.
Another issue is that the PAC algorithm becomes more ill-conditioned as you
approach the carrier. This means that you may have to generate a steady-state
solution with more harmonics to get an accurate simulation as you get closer to
the carrier. So, if you find that the PAC is rolling off at close-in frequencies, you
should rerun HB analysis with a larger number of harmonics. Although,
typically, you will not see improvements in PAC accuracy beyond more than
about 100-200 harmonics.
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Phase Noise Analysis (.PHASENOISE)
Early in your testing, the best way to verify that NLP and PAC are giving
accurate results is to run both algorithms over a broad frequency range and
check that the curves have some range in frequency where they overlap.
Typically, you will see the NLP curve rolling off at 20 to 30 dB/decade as
frequency increases, characteristic of white noise or 1/f noise behavior. Also,
the PAC curve will at first be flat or even noisy close to the carrier. At some point
though, you will see this curve match the NLP roll-off.
The lowest frequency at which the curves overlap defines the point, fPAC above
which the PAC algorithm is valid. Sometimes, by increasing the number of HB
harmonics, it is possible to move fPAC to lower frequencies. The highest
frequency at which the curves overlap defines the point, fNLP below which the
NLP algorithm is valid. A rough rule of thumb is that fPAC = fo/Q, where fo is the
carrier frequency and Q is the oscillator Q-value. This implies that for high-Q
oscillators, such as crystal and some harmonic oscillators, that PAC will be
accurate to values quite close to the carrier.
Broadband Phase Noise Algorithm
The Broadband Phase Noise (BPN) algorithm allows phase noise simulation
over a broad frequency range. The BPN algorithm runs both the NLP and PAC
algorithms and then connects them in the overlap region to generate a single
phase noise curve. This algorithm is ideal for verifying the NLP and PAC
accuracy regions and when you require a phase noise response over a broad
frequency range.
PHASENOISE Output Syntax
HSPICE RF supports the output of the phase noise as well as the phase noise
due to a specified element. In addition, you can output phase noise due to the
specified noise source types. In addition, you can use specialized keywords to
output phase noise due to the specified noise source types, as described
below.
Specified Element
.PRINT PHASENOISE phnoise phnoise(element_name)
.PROBE PHASENOISE phnoise phnoise(element_name)
In this syntax, phnoise is the phase noise parameter.
The .PHASENOISE statement outputs raw data to the *.pn# and *.printpn#
files. HSPICE RF outputs the phnoise data in decibels, relative to the carrier
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Phase Noise Analysis (.PHASENOISE)
signal, per hertz, across the output nodes in the .PHASENOISE statement. The
data plot is a function of the offset frequency. Units are in dBc/Hz.
■
If you use the NLP algorithm (METHOD=0) default, HSPICE RF calculates
only the phase noise component.
■
If you use the PAC algorithm (METHOD=1), HSPICE RF sums both the phase
and amplitude noise components to show the total noise at the output.
■
If you use the BPN algorithm (METHOD=2), HSPICE RF adds both the phase
and amplitude noise components together to show the total noise at the
output. HSPICE RF outputs phnoise to the .pn# file if you set .OPTION
POST.
Element phase noise can also be analyzed through the .PRINT and .PROBE
statements, which the previous syntax shows. A single phnoise keyword
specifies the phase noise for the whole circuit, and the
phnoise(element_name) specifies the phase-noise value of the specified
element.
Example 1
.HBOSC TONE=900MEG NHARMS=9
+ PROBENODE=gate,gnd,0.65
.PHASENOISE V(gate,gnd) DEC 10 100 1.0e7
+ METHOD=0 CARRIERINDEX=1 $use NLP algorithm
This example performs an oscillator analysis, searching for frequencies in the
vicinity of 900 MHz, followed by a phase noise analysis at frequency offsets
from 100 Hz to 10 MHz.
Example 2
.HBOSC TONE=2400MEG NHARMS=11
+ PROBENODE=drainP,drainN,1.0
+ FSPTS=20,2100MEG,2700MEG
+ SWEEP Vtune 0.0 5.0 0.2
.PHASENOISE V(drainP,drainN) DEC 10 100 1.0e7
+ METHOD=0 CARRIERINDEX=1 $use NLP algorithm
This example performs a VCO analysis, searching for frequencies in the vicinity
of 2.4 GHz. This example uses eleven harmonics, and sweeps the VCO tuning
voltage from 0 to 5 V. HSPICE RF uses the nonlinear perturbation (NLP)
algorithm to perform a phase noise analysis about the fundamental frequency
for each tuning voltage value.
Frequency-Dependent and Frequency-Independent Sources
The phnoise_fdep keyword variable will collect all frequency-dependent
noise sources' contributions to the phase noise.
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Phase Noise Analysis (.PHASENOISE)
The phnoise_findep keyword variable will collect all frequency independent
noise sources' contributions.
.print phasenoise phnoise_fdep
.print phasenoise phnoise_findep
Frequency and Bias Dependencies
■
The following syntax is frequency-independent and bias-dependent:
.print phasenoise phnoise_cyclo
Also acceptable is:
.print phasenoise phnoise_cyclostationary
Where:
cyclo or cyclostationary means anything bias-dependent.
■
The following syntax is frequency-independent and bias-independent:
.print phasenoise phnoise_stationary
■
The following syntax is bias-independent and frequency-dependent:
.print phasenoise phnoise_flicker
■
The following syntax is frequency-dependent and bias-dependent:
.print phasenoise phnoise_cycloflicker
Also acceptable is:
.print phasenoise phnoise_cyclostationaryflicker
■
The phnoise_fdep is a combination of phnoise_flicker and
phnoise_cycloflicker.
■
The phnoise_findep is a combination of phnoise_stationary and
phnoise_cyclostationary.
A Noise type suffix can be added to each of these noise terms, phnoise, la,
ltotal, onoise, to select specific noise-type components:
Table 9
170
Summary of Noise Type Dependences
Noise type
frequency-dependent
bias-dependent
phnoise_stationary
No
No
phnoise_cyclostationary
No
Yes
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Phase Noise Analysis (.PHASENOISE)
Table 9
Summary of Noise Type Dependences
Noise type
frequency-dependent
bias-dependent
phnoise_flicker
Yes
No
phnoise_cycloflicker
Yes
Yes
phnoise_fdep
is the union of phnoise_Flicker and
phnoise_cycloflicker noise types
phnoise_findep
is the union of phnoise_stationary and
phnoise_cyclostationary noise types
Where: Noise_term can be phnoise, la, ltotal, onoise (see Amplitude
Modulation/Phase Modulation Separation later in this chapter).
See also Using Noise Analysis Results as Input Noise Sources.
Phase Noise Analysis Options
Table 10 lists the control options specific to PHASENOISE applications.
Table 10
PHASENOISE Analysis Options
Parameter
Description
BPNMATCHTOL=val
Determines the minimum required match between the
NLP and PAC phase noise algorithms. An acceptable
range is 0.05dB to 5dB. The default is 0.5dB.
PHASENOISEKRYLOVDIM (or
PHASENOISE_KRYLOV_DIM
Specifies the dimension of the Krylov subspace that
the Krylov solver uses. This must be an integer greater
than zero. The default is 500.
PHASENOISEKRYLOVITER (or Specifies the maximum number of Krylov iterations
PHASENOISE_KRYLOV_ITER) that the phase noise Krylov solver takes. Analysis
stops when the number of iterations reaches this
value. The default is 1000.
PHASENOISETOL
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Specifies the error tolerance for the phase noise
solver. This must be a real number greater than zero.
The default is 1e-8.
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Phase Noise Analysis (.PHASENOISE)
Table 10
PHASENOISE Analysis Options (Continued)
Parameter
Description
PHNOISE_LORENTZ=val
Turns on a Lorentzian model for the phase noise
analysis.
■
■
■
■
PHNOISEAMPM=1
val=0: uses a linear approximation to a Lorentzian
model and avoids phasenoise values >0dB for low
offsets
val=1 (default): applies a Lorentzian model to all
noise sources
val=2: applies a Lorentzian model to all nonfrequency dependent noise sources
val=3: Lorentzian model applied to white noise
source, Gaussian model applied to flicker noise
sources.
Turns on amplitude modulation/phase modulation
separation. See Amplitude Modulation/Phase
Modulation Separation for details.
Measuring Phase Noise with .MEASURE PHASENOISE
The HSPICE RF optimization flow can read the measured data from a
.MEASURE PHASENOISE analysis. This flow can be combined in the HSPICE
RF optimization routine with a .MEASURE HBTR analysis (see
Using .MEASURE with .HB Analyses on page 124) and a .MEASURE HBNOISE
analysis (see Measuring HBNOISE Analyses with .MEASURE on page 206).
The .MEASURE PHASENOISE syntax supports the following measurements:
■
FIND
.MEASURE PHASENOISE result FIND phnoise at = IFB_value
— yields the result of a variable value at a specific input frequency band
(IFB) point. For example:
.MEASURE PHASENOISE np1 find PHNOISE at=100K
■
WHEN
.MEASURE PHASENOISE result WHEN phnoise=value
—yields the input frequency point at a specific phnoise value. For example:
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Phase Noise Analysis (.PHASENOISE)
.MEASURE PHASENOISE fcorn1 when PHNOISE=-120
■
RMS, average, min, max, and peak-to-peak
.MEASURE PHASENOISE result func phnoise
+ [FROM = IFB1] [TO = IFB2]
—yields the average, RMS, minimum, maximum, or peak-to-peak value of
the phase noise from frequency IFB1 to frequency IFB2, where the value
of func can be RMS, AVG, MIN, MAX or PP. If FROM and TO are not
specified, the value will be calculated over the frequency range specified in
the .PHASENOISE command. For example:
.measure PHASENOISE agn1 AVG phnoise from=100k to=10meg
■
Integral evaluation
.MEASURE PHASENOISE result INTEGRAL phnoise
+ [FROM = IFB1] [TO = IFB2]
—integrates the phase noise value from the IFB1 frequency to the IFB2
frequency. For example:
.MEASURE PHASENOISE rns1 INTEGRAL phnoise from=50k to 500k
■
Derivative evaluation
.MEASURE PHASENOISE result DERIVATIVE phnoise AT = IFB1
—finds the derivative of phase noise at the IFB1 frequency point. For
example:
.MEASURE PHASENOISE fdn1 DERIVATIVE phnoise at=10meg
Note:
.MEASURE PHASENOISE cannot contain an expression that uses
a phasenoise variable as an argument. You also cannot
use .MEASURE PHASENOISE for error measurement and
expression evaluation of the .PHASENOISE command.
See also, the .MEASURE PHASENOISE command in the HSPICE Reference
Manual: Commands and Control Options.
Amplitude Modulation/Phase Modulation Separation
Amplitude Modulation (AM) and Phase Modulation (PM) components of the
total noise can be separated by calculating components in-phase (AM
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Phase Noise Analysis (.PHASENOISE)
component) and in quadrature (PM component) with the carrier using PAC and
BPN PHASENOISE analysis. Output and measure syntax is used to separate
AM/PM noise.
This feature is turned on by setting the .OPTION PHNOISEAMPM=1
(see .OPTION PHNOISEAMPM in the HSPICE Reference Manual: Commands
and Control Options. See also, Important Note for AM/PM Users at the end of
this section.
Keywords for AM/PM separations are:
■
Phase Modulation term only: phnoise
■
Amplitude Modulation term only: la
■
Total phase noise: ltotal
■
Voltage noise: onoise
.PROBE PHASENOISE phnoise [la] [ltotal] [onoise]
.PRINT PHASENOISE phnoise [la] [ltotal] [onoise]
A Noise type suffix can be added to each of these noise terms, phnoise, la,
ltotal, onoise, to select specific noise-type components:
Table 11
Summary of Noise_term
Noise type
frequency-dependent bias-dependent
Noise_term_phnoise_stationary
No
No
Noise_term_phnoise_cyclostationary
No
Yes
Noise_term_phnoise_flicker
Yes
No
Noise_term_phnoise_cycloflicker
Yes
Yes
Noise_term_phnoise_fdep
The union of phnoise_Flicker and
phnoise_cycloflicker noise
types
Noise_term_phnoise_findep
The union of phnoise_stationary
and phnoise_cyclostationary
noise types
Where: Noise_term can be phnoise, la, ltotal, onoise.
Example
.PROBE PHASENOISE phnoise_cyclostationary
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Phase Noise Analysis (.PHASENOISE)
This example outputs the phase modulation noise associated only with
Cyclostationary sources (i.e., sources that are bias dependent, but not
frequency dependent).
Noise Element output is of the form Noise_term (element_name), where
Noise_term can be phnoise, la, ltotal, onoise, and element_name is a
valid netlist element name.
Output File Format
■
File *.printpn#: Writes output from the .PRINT statement when using HB to
obtain the steady state solution.
■
File *.pn#: Writes output from the .PROBE statement when using HB to
obtain the steady state solution.
■
File *.printsnpn#: Writes output from the .PRINT statement when using SN
to obtain the steady state solution.
■
File *.snpn#: Writes output from the .PROBE statement when using SN to
obtain the steady state solution.
Noise source contributions are listed sequentially and are controlled by the
.PHASENOISE command line parameters Listfreq, ListCount, Listfloor,
Listsources. A noise list block will be generated for each output parameter
specified in the .PRINT/.PROBE statement e.g., phnoise, la, ltotal,
onoise.
.MEASURE Syntax and File Format
.MEASURE PHASENOISE extends output variables to the set: am[noise]
pm[noise]
Measure File Format
■
File *.mpn#: Writes output from the .MEASURE statement when using HB
to obtain the steady state solution.
■
File *.msnpn#: Writes output from the .MEASURE statement when using
SN to obtain the steady state solution.
Interpreting Phase Noise Analysis Results
A typical phase noise plot consists of a line, which drops off as a function of
frequency, at a slope of -20dbc/decade where white noise dominates, or 30dbc/decade where flicker noise dominates. At very low offset frequencies,
the phase noise rolls off at according to a Lorentzian shape, such that it never
exceeds 0 dbc/Hz even for very low offset frequencies. The 0 dbc/Hz value
represents the power of the carrier oscillation, at 0 offset frequency. At very
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Phase Noise Analysis (.PHASENOISE)
high offset frequencies, the slope can deviate from -20 dbc/decade due to the
existence of a noise floor or a circuit feedback effect.
Numerical methods for phase noise analysis have limitations. The main
limitation in the PAC phase noise algorithm is that it rolls off too quickly at low
offset frequencies. In the low frequency region, NLP should be trusted. The
main limitation of the NLP algorithm is that it does not cover all high frequency
effects, so PAC should be trusted in the high frequency region.
The BPN algorithm attempts to combine the NLP and PAC results to generate a
single result that is valid for all offset frequencies. It may fail if it cannot identify
an overlap region where NLP and PAC results match. If no overlap region can
be found, the user should attempt to increase nharms on the .HBOSC
command, as this will increase the accuracy of both algorithms, especially PAC.
PAC accuracy is more sensitive to nharms than NLP.
If the phase noise results are suspected to be inaccurate, check the following:
1. Is the .HBOSC steady state solution fully converged?
Explanation: The NLP or PAC small-signal noise analysis requires a highly
accurate steady state solution.
2. Is the phase noise analysis fully converged?
Explanation: Phase noise analysis uses a GMRES iterative linear solver.
If this iterative solver reaches its iteration limit before it is fully converged, the
results are not reliable. Check the number of Krylov iterations that the phase
noise analysis required. If it took the maximum number of iterations (as set
by PHASENOISE_KRYLOV_ITR, default=1000), then the results may not
be fully converged and should not be trusted.
The options PHASENOISE_KRYLOV_DIM, PHASENOISE_KRYLOV_TOL,
and PHASENOISE_KRYLOV_ITR can be used to control the GMRES
solver. You can increase PHASENOISE_KRYLOV_DIM to improve
convergence rate at the expense of memory, or increase
PHASENOISE_KRYLOV_ITR to allow more iterations.
Important Note for AM/PM Users
There are discrepancies that may occur between this feature and the traditional
PAC phase noise analysis in HSPICE RF. Total phase noise (i.e., ltotal) is
the sum of two terms, the amplitude modulation (am) and phase modulation
(phnoise). Traditionally, PAC phase noise reports the phnoise (phase
modulation component) and ltotal (total phase noise) terms as identical,
with the assumption that the am term (amplitude modulation component) was
zero.
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Accumulated Jitter Measurement for Closed Loop PLL Analysis
The PAC phase noise am/pm feature described in this section separately
calculates the am and phnoise components. All phase noise measurements
involving either PAC or BPN will be affected. In most cases the differences
between PHNOISEAMPM=1 and =0 will be small unless you expect a significant
AM component. You may see a slight decrease in the new phase noise (phase
modulation) component compared to the old calculation.
For example, the random jitter calculations HSPICE RF uses are accurate only
when they involve the PM component of phase noise. A small error may be
introduced when they are based on ltotal, or AM noise is included.
NLP phase noise (method=0) only calculates the phnoise component and is
not affected by the am/pm option.
BPN phase noise (method=2) is affected in that the far side component is
derived from the PAC phase noise.
Workaround: Make sure that.OPTION PHNOISEAMPM=0 (the default) to
assure that Periodic AC phase noise amplitude modulation (AM) component is
set to zero to maintain backward compatibility and traditional results for phnoise
and jitter, for example.
Accumulated Jitter Measurement for Closed Loop PLL
Analysis
Enhancements to HSPICE RF include considerable support for a variety of
jitter measurements. Many of these are important in a PLL flow, where the
HBOSC or SNOSC analyses are used to compute a phase noise response for
an oscillator or VCO, and the resulting random jitter is derived from phase
noise. In the PLL methodology, other HSPICE RF analyses are used to
compute phase noise contributions from the other PLL building block. A closed
loop analysis is then performed, using phase-domain models for both signal
and noise responses, that takes into account the noise contributions from all
such blocks. To complete this flow is the ability to compute “Accumulated Jitter”
or “Timing Jitter” for the closed loop PLL. The accumulated jitter response is
essentially an integral transformation of the closed-loop PLL response. The
following sections show how accumulated jitter also be measured directly from
the phase noise output of an open loop oscillator analysis.
In the PLL flow, the closed loop phase noise must be interpreted from the
results of a linear HSPICE RF .AC/.NOISE analysis. The following sections
describe a capability that allows direct measurement of accumulated jitter from
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Accumulated Jitter Measurement for Closed Loop PLL Analysis
the results of this closed loop noise analysis, without any special interpretation
of the results.
Jitter Measurements from Phase Noise
These topics are discussed in the following sections:
■
Jitter Definitions
■
Jitter Output Syntax
■
.MEASURE Statements for Jitter
■
Peak-to-Peak Jitter
Jitter Definitions
HSPICE RF provides several random jitter (RJ) measurements. This section
defines, describes, and compares the various jitter measurements provided.
Random jitter measurements are derived from the results of an HSPICE RF
phase noise analysis. The relationships between phase noise and the random
jitter measurements are presented here, and their means for calculation. The
types of random jitter measurements include: Timing, Phase, Period, Tracking,
Long-Term, and Cycle-to-Cycle Jitter.
Timing jitter is a measurement of oscillator uncertainty in the time domain. For
clock applications, time domain measurements are preferable, since most
specifications of concern involve time domain values.
Timing jitter is the standard deviation of the timing uncertainty, which is a
function of the auto-correlation function in the power spectrum of the phase
variations. Timing Jitter is the square root of the variance (standard deviation
squared) of the timing uncertainty between two clock edges separated by an
interval given by τ = N ⋅ T o , where T o is the ideal clock period. It can be
written as a function of the auto-correlation function of the power spectrum of
phase variations as:
Equation 32
2
2
σTIE ( τ ) = ------[ R φ( 0 ) – R φ( τ ) ]
2
ωo
where TIE refers to the Time Interval Error. This measurement is known as
Timing Jitter, Accumulated Jitter, or N-Cycle Jitter, since it represents the jitter
that may accumulate over an interval of many periods.
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The Weiner-Khintchine Theorem [1] relates the auto correlation function to the
power spectrum of phase variations as in the following equation:
∞
∞
Equation 33
1
jωτ
R φ( τ ) = ------ ∫ S φ( ω)e dω= 2 ∫ L ( f ) cos ( 2πfτ ) df
2π
–∞
0
where S φ( ω) is the double-sided power spectrum of phase variations, and L ( f )
is the single-sideband phase noise. The auto-correlation for τ = 0 is given by
∞
Equation 34
R φ( 0 ) ≡
2
φrms
= 2 ∫ L ( f ) df
0
which defines φrms in HSPICE RF known as RMS Phase Jitter.
2
Using the identity 2 sin α = 1 – cos 2α we can then write:
∞
Equation 35
2
σTIE
8
2
( τ ) = ------L ( f ) sin ( πfτ ) df
2 ∫
ωo
0
to enable currently supported HSPICE RF jitter measurements to be written as:
∞
Equation 36
φrms = σph ⋅ ω0 =
∞
2 ∫ L ( f ) df
“RMS Phase Jitter”
0
2
2
σTIE ( τ ) = ----- 2 ∫ L ( f )sin ( πfτ )df “Timing (Time Interval Error) Jitter”
ω0
0
From these definitions, several other key jitter measurements can be derived,
including Period Jitter, Tracking Jitter, Long-Term Jitter, and Cycle-to-Cycle
Jitter.
Period Jitter is equivalent to the value for Timing Jitter for a one period interval.
We therefore have:
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Accumulated Jitter Measurement for Closed Loop PLL Analysis
∞
Equation 37
σPER
2
2
= σTIE ( T 0 ) = ----- 2 ∫ L ( f )sin ( πfT 0 )df
ω0
"Period Jitter"
0
Tracking Jitter is equivalent to the value (in units of seconds) for RMS Phase
Jitter, or:
∞
Equation 38
σtr = σph
φrms
1
= --------- = ----- 2 ∫ L ( f )df “Tracking Jitter”
ω0
ω0
0
Long-Term Jitter is equivalent to
Equation 39
2 times the Tracking Jitter, i.e.:
σΔT →∞ = σTIE ( τ →∞) =
φrms
2
2 --------- = ----ω0
ω0
∞
∫
L ( f ) df
“Long-Term Jitter”
0
Cycle-to-Cycle Jitter is based on the difference between adjacent Period Jitter
measurements. It is given by:
Equation 40
σCTC =
2
2
4σPER – σTIE ( 2T 0 )
“Cycle-to-Cycle Jitter”
In general, each of the above calculations must be performed carefully over
limits of integration to accurately calculate jitter expressions based on the finite
frequency limits provided for the phase noise analysis. Linear interpolation is
used, but the phase noise generally follows more of a power law expansion.
Jitter Output Syntax
The timing jitter calculations are derived from the results of phase noise
analysis. The phase noise output syntax supports the JITTER keyword as an
output keyword in addition to the PHNOISE keyword.
.PRINT PHASENOISE PHNOISE JITTER
.PROBE PHASENOISE PHNOISE JITTER
If the JITTER keyword is present, the .PHASENOISE statement also outputs
the raw jitter data to *.jt0 and *.printjt0 data files. The PHNOISE data is given in
units of dBc/Hz, i.e., dB relative to the carrier, per Hz, across the output nodes
specified by the PHASENOISE statement. The data plot is a function of offset
frequency. If the JITTER keyword is present, .PHASENOISE outputs the TIE
Timing Jitter (Accumulated Jitter) data to *.jt0 and *.printjt0 data files. These
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data are plotted as a function of time in units of seconds. The jitter calculations
make use of some of the parameters given in the .PHASENOISE syntax (see
PHASENOISE Input Syntax for the syntax and examples.).
The time samples for timing jitter output make use of the same number of
points as the phase noise frequency sweep specification.
The output of timing jitter information uses a corresponding time sampling
derived via:
Equation 41
1
2
N
τ 1 = ------, τ 2 = ------, ...,τ N = -----T0
T0
T0
.MEASURE Statements for Jitter
The jitter-specific .MEASURE statements specify the jitter keywords as follows.
(For discussion of the BER parameter, see below.)
.MEASURE PHASENOISE Jname PERJITTER phnoise
+ [UNITS=(sec|rad|UI)] [BER=val]
.MEASURE PHASENOISE Jname CTCJITTER phnoise
+ [UNITS=(sec|rad|UI)] [BER=val]
.MEASURE PHASENOISE Jname RMSJITTER phnoise
+ [FROM start_frequency] [TO end_frequency]
+ [UNITS=(sec|rad|UI)] [BER=val]
.MEASURE PHASENOISE Jname PHJITTER phnoise
+ [FROM start_frequency] [TO end_frequency]
+ [UNITS=(sec|rad|UI)] [BER=val]
.MEASURE PHASENOISE Jname TRJITTER phnoise
+ [FROM start_frequency] [TO end_frequency]
+ [UNITS=(sec|rad|UI)] [BER=val]
.MEASURE PHASENOISE Jname LTJITTER phnoise
+ [FROM start_frequency] [TO end_frequency]
+ [UNITS=(sec|rad|UI)] [BER=val]
RMSJITTER, PHJITTER, and TRJITTER are synonymous measurements, all
based on the calculations described related to the RMS Phase Jitter value in
units of seconds given by σph = φrms ⁄ ω0 . These measurements allow control
of the integration range using the FROM and TO parameters. The
measurements for PERJITTER, and CTCJITTER use the full offset frequency
sweep range given for the phase noise analysis to compute values (the FROM
and TO parameters are ignored if entered).
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As given currently in HSPICE RF, the frequency intervals can be modified for
these jitter calculations (if desired, although not recommended), and UNITS
can be selected between seconds, radians, and Unit Intervals. The following
table specifies the calculation used for units=seconds for each jitter
measurement.
MEASURE name
Calculation used (Units=sec)
RMSJITTER
σph = φrms ⁄ ω0
PHJITTER
σph = φrms ⁄ ω0
TRJITTER
σph = φrms ⁄ ω0
PERJITTER
σPER
LTJITTER
σΔT →∞ =
CTCJITTER
σCTC
2φrms ⁄ ωo
Example
.meas phasenoise rj RMSJITTER phnoise from 1K to 100K
+ units = rad
Peak-to-Peak Jitter
As noted in .MEASURE Statements for Jitter, an additional BER (Bit Error
Rate) parameter is supported. This parameter allows you to convert any jitter
value from an RMS value into a Peak-to-Peak value. The RMS jitter values
correspond to a 1-sigma standard deviation value for the Gaussian distribution
of the jitter. Peak-to-peak values represent the full span of the Gaussian
distribution. Since this span is theoretically unbounded for truly random
distributions, the conversion to peak-to-peak values has to be interpreted as
spanning some number of sigma values. You can arrive at this number (i.e.,
“sigma multiplier”) by specifying a corresponding Bit Error Rate.
The term “BER” corresponds to the unitless Bit Error Rate that allows for this
conversion. The following table shows some example conversions from various
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BER values into a “sigma multiplier” value which corresponds to the number of
sigma standard deviations in converting from RMS to peak-to-peak values:
Bit Error Rate
Sigma Multiplier
10-3
6.180
10-4
7.438
10-5
8.530
10-6
9.507
10-7
10.399
10-8
11.224
10-9
11.996
10-10
12.723
10-11
13.412
10-12
14.069
10-13
14.698
10-14
15.301
10-15
15.883
10-16
16.444
These conversions are done in accordance with the relationship:
Equation 42
1--α
erfc ----------------- = BER
2
2⋅ 2
where, erfc is the complementary error function, and α is the Sigma Multiplier.
Support for peak-to-peak conversions is included for a continuous range of
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Small-Signal Phase-Domain Noise Analysis (.ACPHASENOISE)
BER values from 10
range).
– 16
–3
≤ α ≤ 10 (and some values extrapolated outside this
Specification of the BER parameter results in the output of the Peak to Peak
jitter value, and not the RMS value. Labels for the measurements show
appropriate “rms” and “p-p” labels. A BER parameter set to BER=0 is
equivalent to having no parameter, and only results in the RMS calculation.
Errors/Warnings
Error handling and recovery is exercised to capture obvious errors in input
specifications. The following error checking is performed:
■
Calculations are be performed if oscillator or phase noise analysis fails.
■
ERROR if L(f) > 1 over any part of the frequency sweep (non-dB form).
■
ERROR if L(f) < 0 over any part of the frequency sweep (non-dB form).
■
Error if any time or frequency samples are negative values.
■
ERROR if BER < 0 for any Jitter measurement.
■
WARNING if BER > 1 for any Jitter measurement.
■
WARNING if f0 < 10 Hz. Message: “Jitter calculations may be ineffective for
offset frequencies under 10 Hz.”
Small-Signal Phase-Domain Noise Analysis
(.ACPHASENOISE)
To see the influence that oscillator or VCO phase noise can have on a system
where it is present, it is necessary to perform a phase-domain analysis where
the circuit variables are phase, and the input noise stimuli are phase noise. This
is the purpose of the .ACPHASENOISE analysis in HSPICE RF.
This type of analysis is critical, for example, in analyzing the effects of noise in
a phase-locked loop (PLL). In a PLL design flow, the HBOSC or SNOSC
analyses are used to compute a phase noise response for an oscillator or VCO.
HSPICE RF analyses can be used to compute phase noise contributions from
the other PLL building blocks. A closed loop PLL analysis can then be
performed by using phase-domain models for both signal and noise responses,
where the noise contributions from all blocks are input as phase noise stimuli.
Such an analysis can be performed to determine the PLL closed-loop phase
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Small-Signal Phase-Domain Noise Analysis (.ACPHASENOISE)
noise, based on the contributions of each block, determined by an open loop
analysis.
AC Phase Noise Analysis Syntax
A small-signal phase-domain analysis, such as that useful for PLL noise
analyses, can use a methodology based on small-signal .AC and .NOISE
analyses, where the circuit analyzed is a phase-domain modeled circuit (not
voltage/current domain), and the results are therefore interpreted accordingly
as phase variables. The variables of the associated noise analysis must
therefore interpreted as phase noise variables. A normal .AC analysis
command can be used to activate the small-signal analysis and specify its
LIN/OCT/DEC/POI or SWEEPBLOCK frequency sweep. However, to properly
interpret signal and noise quantities as phase variables, the following command
properly formats output in terms of phase noise variables. The syntax is:
.ACPHASENOISE output input [interval] carrier=freq
+ [listfreq=(frequencies|none|all)]
+ [listcount=val] [listfloor=val]
+ [listsources=(1|0)]
where:
■
output
Node voltage or branch current output variable
■
input
Independent source used as input reference
■
interval Number of intervals for which to dump jitter and noise summary
information
■
freq
Frequency (in Hz) of the fundamental carrier upon which the
noise transformations are based
■
list…
List parameters usage is consistent with other HSPICE noise
analyses
ACPHASENOISE Analysis .PRINT/.PROBE Syntax
The unique aspect of the .ACPHASENOISE analysis is that it allows the small
signal noise calculation results to be interpreted as phase noise values. The
available .print/.probe measurements reflect this. The .print/.probe
output syntax are the “JITTER” and “PHNOISE” keywords consistent with the
HSPICE RF .phasenoise analysis, namely:
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Small-Signal Phase-Domain Noise Analysis (.ACPHASENOISE)
.PRINT ACPHASENOISE PHNOISE JITTER
.PROBE ACPHASENOISE PHNOISE JITTER
As with the .PHASENOISE analysis, the .ACPHASENOISE analysis outputs raw
data to *.pn0 and *.printpn0 files. The PHNOISE data is given in units of dBc/Hz,
i.e., dB relative to the carrier, per Hz, across the output nodes specified by the
.ACPHASENOISE statement. The data plot is a function of offset frequency. If
the “JITTER” keyword is present, .ACPHASENOISE also outputs the
accumulated TIE jitter data to *.jt0 and *.printjt0 data files. These data are
plotted as a function of time in units of seconds. The Timing Jitter data itself has
units of seconds. The timing jitter calculations make use of the parameters
given in the .ACPHASENOISE syntax, such as “freq” and “interval”.
Se also Using Noise Analysis Results as Input Noise Sources.
.MEASURE Support for ACPHASENOISE
Single valued jitter measurements are available from .MEASURE statements.
Examples include period jitter, cycle-to-cycle jitter, and phase jitter
measurements, respectively, as shown below:
.MEASURE ACPHASENOISE Jname PERJITTER phnoise
+ [UNITS=(sec|rad|UI)] [BER=val]
.MEASURE ACPHASENOISE Jname CTCJITTER phnoise
+ [UNITS=(sec|rad|UI)] [BER=val
.MEASURE ACPHASENOISE Jname PHJITTER phnoise
+ [FROM start_frequency [TO end_frequency]
+ [UNITS=(sec|rad|UI)] [BER=val]
Errors and Warnings
Error checking of values are consistent with that used for the .PHASENOISE
analysis.
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References
References
[1] E. Ngoya, A. Suarez, R. Sommet, R. Quere, “Steady State Analysis of Free
or Forced Oscillators by Harmonic Balance and Stability Investigation of
Periodic and Quasi-Periodic Regimes,” International Journal of Microwave
and Millimeter-Wave Computer-Aided Engineering, Volume 5, Number 3,
pages 210-223 (1995)
[2] C.R. Chang, M.B. Steer, S. Martin, E. Reese, “Computer-Aided Analysis of
Free-Running Microwave Oscillators,” IEEE Trans. on Microwave Theory
and Techniques, Volume 39, No. 10, pages 1735-1745, October 1991.
[3] G.D. Vendelin, Design of Amplifiers and Oscillators by the S-Parameter
Method, John Wiley & Sons, 1982
[4] A. Demir, A. Mehrotra, J. Roychowdhury, “Phase Noise in Oscillators: A
Unifying Theory and Numerical Methods for Characterization” in Proc. IEEE
DAC, pages 26-31, June 1998.
[5] A. Demir, A. Mehrotra, and J. Roychowdhury, “Phase Noise in Oscillators: A
Unifying Theory and Numerical Methods for Characterization,” IEEE Trans.
Circuits System I, Volume 47, pages 655–674, May 2000.
[6] A. van der Ziel, Noise in Solid State Devices and Circuits, John Wiley &
Sons, 1986.
[7] A. Hajimiri, S. Limotyrakis, and T.H. Lee, “Jitter and phase noise in ring
oscillators,” IEEE J. Solid-State Circuits, vol. 34, no. 6, pp. 790-804, June
1999.
[8] Jitter Analysis Techniques for High Data Rates, Application Note 1432,
Agilent Technologies, Feb. 2003.
[9] Characterization of Clocks and Oscillators, NIST Technical Note 1337,
National Institute of Standards and Technology.
[10] G.V. Klimovitch, “Near-carrier oscillator spectrum due to flicker and white
noise,” Proc. ISCAS 2000 (Geneva), May 2000.
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References
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8
Large Signal Periodic AC, Transfer Function, and
Noise Analyses
8
Describes how to use both harmonic balance-based and Shooting Newtonbased AC, and transfer function analyses, as well as nonlinear, steady-state
noise analysis.
The following topics are presented in this section:
■
Multitone Harmonic Balance AC Analysis (.HBAC)
■
Shooting Newton AC Analysis (.SNAC)
■
Multitone Harmonic Balance Noise (.HBNOISE)
■
Shooting Newton Noise Analysis (.SNNOISE)
■
Periodic Time-Dependent Noise Analysis (.PTDNOISE)
■
Multitone Harmonic Balance Transfer Function Analysis (.HBXF)
■
Shooting Newton Transfer Function Analysis (.SNXF)
Multitone Harmonic Balance AC Analysis (.HBAC)
You use the .HBAC (Harmonic Balance AC) statement for analyzing linear
behavior in large-signal periodic systems. The .HBAC statement uses a
periodic AC (PAC) algorithm to perform linear analysis of autonomous
(oscillator) or nonautonomous (driven) circuits, where the linear coefficients are
modulated by a periodic, steady-state signal.
Multitone HBAC analysis extends single-tone HBAC to quasi-periodic systems
with more than one periodic, steady-state tone. One application of multitone
HBAC is to more efficiently determine mixer conversion gain under the
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Multitone Harmonic Balance AC Analysis (.HBAC)
influence of a strong interfering signal than is possible by running a swept
three-tone HB simulation.
The following sections discuss these topics:
■
Prerequisites and Limitations
■
Input Syntax
■
Output Syntax
■
HBAC Output Data Files
■
Errors and Warnings
Prerequisites and Limitations
The following prerequisites and limitations apply to HBAC:
190
■
Requires one and only one .HBAC statement. If you use multiple .HBAC
statements, HSPICE RF uses only the last .HBAC statement.
■
Requires one and only one .HB statement.
■
Supports arbitrary number of tones.
■
Requires placing the parameter sweep in the .HB statement.
■
Requires at least one HB source.
■
Requires at least one HBAC source.
■
Supports unlimited number of HB and HBAC sources.
■
The requested maximum harmonic in a .PROBE or .PRINT statement must
be less than or equal to half the number of harmonics specified in harmonic
balance (that is, max_harm <= num_hb_harms / 2).
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Multitone Harmonic Balance AC Analysis (.HBAC)
Input Syntax
.HBAC frequency_sweep
Parameter
Description
frequency_sweep
Frequency sweep range for the input signal (also referred to
as the input frequency band (IFB) or fin). You can specify LIN,
DEC, OCT, POI, or SWEEPBLOCK. Specify the nsteps, start,
and stop frequencies using the following syntax for each type
of sweep:
■
■
■
■
■
■
LIN nsteps start stop
DEC nsteps start stop
OCT nsteps start stop
POI nsteps freq_values
SWEEPBLOCK nsteps freq1 freq2 ... freqn
DATA=dataname
HBAC Analysis Options
The following options directly relate to a HBAC analysis and override the
corresponding PAC options if specified in the netlist:
■
.OPTION HBACTOL, default = 1x10-8, Range = 1x10-14 to Infinity
■
.OPTION HBACKRYLOVDIM, default = 300, Range = 1 to Infinity
■
.OPTION HBACKRYLOVITER | HBAC_KRYLOV_ITER, default = 1000,
Range = 1 to Infinity
If these parameters are not specified, then the following conditions apply:
■
If HBACTOL > HBTOL, then HBACTOL = HBTOL
■
If HBACKRYLOVDIM < HBKRYLOVDIM, then HBACKRYLOVDIM =
HBKRYLOVDIM
Output Syntax
This section describes the syntax for the HBAC .PRINT and .PROBE
statements. These statements are similar to those used for HB analysis.
.PRINT and .PROBE Statements
.PRINT HB TYPE(NODES | ELEM)[INDICES]
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Multitone Harmonic Balance AC Analysis (.HBAC)
.PROBE HB TYPE(NODES | ELEM)[INDICES]
Parameter
Description
TYPE
Specifies a harmonic type node or element.
TYPE can be one of the following:
■
■
■
■
NODES |
ELEM
NODES or ELEM can be one of the following:
■
■
■
■
192
Voltage type –
V = voltage magnitude and phase in degrees
VR = real component
VI = imaginary component
VM = magnitude
VP - Phase in degrees
VPD - Phase in degrees
VPR - Phase in radians
VDB - dB units
VDBM - dB relative to 1 mV
Current type –
I = current magnitude and phase in degrees
IR = real component
II = imaginary component
IM = magnitude
IP - Phase in degrees
IPD - Phase in degrees
IPR - Phase in radians
IDB - dB units
IDBM - dB relative to 1 mV
Power type – P
Frequency type – hertz[index], hertz[index1, index2, ...] You must specify the
harmonic index for the hertz variable. The frequency of the specified harmonics
is dumped.
Voltage type – a single node name (n1), or a pair of node names, (n1,n2)
Current type – an element name (elemname)
Power type – a resistor (resistorname) or port (portname) element name
Frequency type – the harmonic index for the hertz variable. The frequency of
the specified harmonics is dumped.
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Multitone Harmonic Balance AC Analysis (.HBAC)
Parameter
Description
INDICES
Index to tones in the form [n1, n2, ..., nK, +/-1].
■
■
nj is the index of the j-th HB tone and the .HB statement contains K tones
+/-1 is the index of the HBAC tone
Wildcards are not supported if this parameter is used.
You can transform HB data into the time domain and output by using the following
syntax:.PRINT HBTRAN ov1 [ov2 ... ovN].PROBE HBTRAN ov1 [ov2 ... ovN]. See
TYPE above for voltage and current type definitions.
HBAC Output Data Files
An HBAC analysis produces these output data files:
■
Output from the .PRINT statement is written to a .printhb# file. This data is
against the IFB points.
•
The header contains the large-signal fundamental and the range of
small-signal frequencies.
•
The columns of data are labeled as F(Hz), followed by the output
variable names. Each variable name has the associated mixing pair
value appended.
All N variable names and all M mixing pair values are printed for each
swept small-signal frequency value (a total of N*M for each frequency
value).
■
Output from the .PROBE statement is written to a .hb# file. This data is
against the IFB points.
■
Reported performance log statistics are written to a .lis file:
•
Number of nodes
•
Number of FFT points
•
Number of equations
•
Memory in use
•
CPU time
•
Maximum Krylov iterations
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Multitone Harmonic Balance AC Analysis (.HBAC)
•
Maximum Krylov dimension
•
Target GMRES residual
•
GMRES residual
•
Actual Krylov iterations taken
•
Frequency (swept input frequency values).
Errors and Warnings
The following error and warning messages are used when HSPICE encounters
a problem with a HBAC analysis.
Error Messages
HBAC frequency sweep includes negative frequencies. HBAC allows only
frequencies that are greater than or equal to zero.
No HB statement is specified (error at parser). HBAC requires an HB statement
to generate the steady-state solution.
Warning Messages
More than one HBAC statement (warning at parser). HSPICE RF uses only the
last HBAC statement in the netlist.
No HBAC sources are specified (error at parser). HBAC requires at least one
HBAC source.
GMRES Convergence Failure. When GMRES (Generalized Minimum
Residual) reaches the maximum number of iterations and the residual is
greater than the specified tolerance. The HBAC analysis generates a warning
and then continue as if the data were valid. This warning reports the following
information:
194
■
Final GMRES Residual
■
Target GMRES Residual
■
Maximum Krylov Iterations
■
Actual Krylov Iterations taken
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Chapter 8: Large Signal Periodic AC, Transfer Function, and Noise Analyses
Shooting Newton AC Analysis (.SNAC)
HBAC Example
The following example is shipped with the HSPICE RF distribution as
mix_hbac.sp and is available in directory:
$installdir/demo/hspicerf/examples.
* Test HBAC: ideal I,Q mixer
.OPTIONS PROBE
.OPTIONS POST=2
vlo lo 0 1.0 cos(1.0 0.5 1g) TRANFORHB=1 $ Periodic, Large-Signal
Input
rlo lo 0 1.0
rrf rf 0 1.0 $ Noise source
rrf1 rf1 rf 1.0 $ Noise source
g1 0 if cur='1.0*v(lo)*v(rf)' $ mixer element
c1 0 if q='1.0e-9*v(lo)*v(rf)' $ mixer element
rout if ifg 1.0
vctrl ifg 0 0.0
h1 out 0 vctrl 1.0
rh1 out 0 1.0
vrf rf1 0 hbac .001 0 $ Small signal source
.hb tones=1.0g nharms=3
.hbac lin 1 0.8g 0.8g
.print hb v(rf1) v(lo) v(out)
.probe hb v(rf1) v(lo) v(out)
.measure hb vout1 find v(out)[1,-1] at=0.8g
.end
Shooting Newton AC Analysis (.SNAC)
You use the Shooting Newton AC (.SNAC) statement for analyzing linear
behavior in large-signal periodic systems. The .SNAC statement uses a
periodic AC (PAC) and Shooting Newton algorithm to perform linear analysis of
nonautonomous (driven) circuits, where the linear coefficients are modulated
by a periodic, steady-state signal.
The following section describes the periodic AC analysis based on a Shooting
Newton algorithm. This functionality is similar to the Harmonic Balance (HBAC)
for periodic AC analysis.
The following section discuss these topics:
■
Prerequisites and Limitations
■
Input Syntax
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Shooting Newton AC Analysis (.SNAC)
■
Output Syntax
■
SNAC Output Data Files
■
Errors and Warnings
■
SNAC Example
Prerequisites and Limitations
The following prerequisites and limitations apply to SNAC:
■
Requires one and only one .SNAC statement. If you use multiple .SNAC
statements, HSPICE RF uses only the last .SNAC statement.
■
Requires one and only one .SN statement.
■
Requires placing the parameter sweep in the .SN statement.
■
Requires at least one Periodic source.
■
Limited to simulations that can be reduced to a single tone SN analysis.
■
Supports unlimited number of sources.
■
The requested maximum harmonic in a .PROBE or .PRINT statement must
be less than or equal to half the number of harmonics specified in the SN
statement (that is, max_harm ≤ nharms / 2).
Input Syntax
.SNAC frequency_sweep
Parameter
Description
frequency_sweep
Frequency sweep range for the input signal (also referred to as the input
frequency band (IFB) or fin). You can specify LIN, DEC, OCT, POI, or
SWEEPBLOCK. Specify the nsteps, start, and stop frequencies using the
following syntax for each type of sweep:
■
■
■
■
■
■
196
LIN nsteps start stop
DEC nsteps start stop
OCT nsteps start stop
POI nsteps freq_values
SWEEPBLOCK nsteps freq1 freq2 ... freqn
DATA=dataname
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Chapter 8: Large Signal Periodic AC, Transfer Function, and Noise Analyses
Shooting Newton AC Analysis (.SNAC)
Output Syntax
This section describes the syntax for the SNAC .PRINT and .PROBE
statements. These statements are similar to those used for HB analysis.
.PRINT and .PROBE Statements
.PRINT SN TYPE(NODES | ELEM)[INDICES]
.PROBE SN TYPE(NODES | ELEM)[INDICES]
Parameter
Description
TYPE
Specifies a harmonic type node or element.
TYPE can be one of the following:
■
■
■
■
Voltage type –
V = voltage magnitude and phase in degrees
VR = real component
VI = imaginary component
VM = magnitude
VP - Phase in degrees
VPD - Phase in degrees
VPR - Phase in radians
VDB - dB units
VDBM - dB relative to 1 mV
Current type –
I = current magnitude and phase in degrees
IR = real component
II = imaginary component
IM = magnitude
IP - Phase in degrees
IPD - Phase in degrees
IPR - Phase in radians
IDB - dB units
IDBM - dB relative to 1 mV
Power type – P
Frequency type – hertz[index], hertz[index1, index2, ...] You must specify the
harmonic index for the hertz variable. The frequency of the specified
harmonics is dumped.
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Parameter
Description
NODES |
ELEM
NODES or ELEM can be one of the following:
■
■
■
■
INDICES
Voltage type – a single node name (n1), or a pair of node names, (n1,n2)
Current type – an element name (elemname)
Power type – a resistor (resistorname) or port (portname) element name
Frequency type – the harmonic index for the hertz variable. The frequency of
the specified harmonics is dumped.
Index to tones in the form [n1, +/-1].
■
■
n1 is the index of the SN tone
+/-1 is the index of the SNAC tone
Wildcards are not supported if this parameter is used.
You can transform SN data into the time domain and output by using the following
syntax:.PRINT SNTRAN ov1 [ov2 ... ovN]. PROBE SNTRAN ov1 [ov2 ... ovN].
See TYPE above for voltage and current type definitions.
SNAC Output Data Files
A SNAC analysis produces these output data files:
■
Output from the .PRINT statement is written to a .printsnac# file.
■
This data is against the IFB points.
■
The header contains the large-signal fundamental and the range of smallsignal frequencies.
■
The columns of data are labeled as F(Hz), followed by the output variable
names. Each variable name has the associated mixing pair value
appended. All N variable names and all M mixing pair values are printed for
each swept small-signal frequency value (a total of N*M for each frequency
value).
■
Output from the .PROBE statement is written to a .snac# file.
Reported performance log statistics are written to a .lis file:
198
■
Number of nodes
■
Number of FFT points
■
Number of equations
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Shooting Newton AC Analysis (.SNAC)
■
Memory in use
■
CPU time
■
Maximum Krylov iterations
■
Maximum Krylov dimension
■
Target GMRES residual
■
GMRES residual
■
Actual Krylov iterations taken
■
Frequency (swept input frequency values)
Errors and Warnings
The following error and warning messages are used when HSPICE encounters
a problem with a SNAC analysis.
Error Messages
SNAC frequency sweep includes negative frequencies. SNAC allows only
frequencies that are greater than or equal to zero.
No SN statement is specified (error at parser). SNAC requires an SN statement
to generate the steady-state solution.
Warning Messages
More than one SNAC statement (warning at parser). HSPICE RF uses only the
last SNAC statement in the netlist.
No SNAC sources are specified (error at parser). SNAC requires at least one
SNAC source.
GMRES Convergence Failure. When GMRES (Generalized Minimum
Residual) reaches the maximum number of iterations and the residual is
greater than the specified tolerance. The SNAC analysis generates a warning
and then continue as if the data were valid. This warning reports the following
information:
■
Final GMRES Residual
■
Target GMRES Residual
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Phase Noise and Buffer Chains
■
Maximum Krylov Iterations
■
Actual Krylov Iterations taken
SNAC Example
The following example is shipped with the HSPICE RF distribution as
mix_snac.sp and is available in directory:
$installdir/demo/hspicerf/examples.
* Test SNAC: ideal I,Q mixer -rrd
.OPTIONS PROBE
.OPTIONS POST=2
$.OPTIONS snmaxiter=100
.OPTIONS SNACCURACY=5
vlo lo 0 1.0 cos(1.0 0.5 1g) $ Periodic, Large-Signal SN Input
rlo lo 0 1.0
rrf rf 0 1.0 $ Noise source
rrf1 rf1 rf 1.0 $ Noise source
g1 0 if cur='1.0*v(lo)*v(rf)' $ mixer element
c1 0 if q='1.0e-9*v(lo)*v(rf)' $ mixer element
rout if ifg 1.0
vctrl ifg 0 0.0
h1 out 0 vctrl 1.0
rh1 out 0 1.0
vrf rf1 0 snac .001 24.0 $ Small signal for SNAC with 1-tone
SN Input
.sn tones=1.0g nharms=3
.snac lin 1 0.8g 0.8g
.print sn v(rf1) v(lo) v(out)
.print snfd v(rf1) v(lo) v(out)
.print snac v(rf1) v(lo) v(out)
.measure snac vout1 find v(out)[1,-1] at=0.8g
.measure snac vout2 find v(out)[0,1] at=0.8g
.measure snac vout3 find v(out)[1,1] at=0.8g
.measure sn vlo1 find v(lo) at=0.5n
.measure sn vlo2 find v(lo) at=1n
.measure snfd vlo3 find v(lo)[1] at=1
.end
Phase Noise and Buffer Chains
Phase noise is specific to oscillators. However, for buffer chains you can do
periodic noise analysis. Phase noise that may be contributed by buffer,
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Multitone Harmonic Balance Noise (.HBNOISE)
amplifier, divider, or multiplier circuits is often referred to as residual phase
noise. There are three commands in HSPICE RF that can apply help you
predict such noise: .HBNOISE, .SNNOISE, and .PTDNOISE. These analyses
compute the noise spectral density at an output variable taking into
consideration modulation effects.
.HBNOISE and .SNNOISE compute the average noise over one period,
assuming your circuit is driven by a periodic input signal.
.PTDNOISE computes the noise at one specific time point within the period, or
it can compute the noise as a function of time over one period. .PTDNOISE can
also convert the noise to a “jitter” value, which would be an uncertainty in the
timing as opposed to the uncertainty in the output voltage.
See the following sections for detailed information on these commands:
■
Multitone Harmonic Balance Noise (.HBNOISE)
■
Shooting Newton Noise Analysis (.SNNOISE)
■
Periodic Time-Dependent Noise Analysis (.PTDNOISE)
Multitone Harmonic Balance Noise (.HBNOISE)
An HBNOISE (Harmonic Balance noise) analysis simulates the noise behavior
in periodic systems and is designed for use with driven circuits. It employs a
Periodic AC (PAC) algorithm to perform noise analysis of nonautonomous
(driven) circuits under periodic, steady-state tone conditions. This can be
extended to quasi-periodic systems having more than one periodic, steadystate tone. One application for a multitone HBNOISE analysis is determining
mixer noise figures under the influence of a strong interfering signal.
The PAC method simulates noise assuming that the stationary noise sources
and/or the transfer function from the noise source to a specific output are
periodically modulated.
■
The modulated noise source (thermal, shot, or flicker) is modeled as a
cyclostationary noise source.
■
A PAC algorithm solves the modulated transfer function.
■
You can also use the HBNOISE PAC method with correlated noise sources,
including the MOSFET level 9 and level 11 models, and the behavioral noise
source in the G-element (Voltage Dependent Current Source).
You use the .HBNOISE statement to perform a Periodic Noise Analysis.
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The following sections discuss these topics:
■
Supported Features
■
Input Syntax
■
Output Syntax
■
Output Data Files
■
Measuring HBNOISE Analyses with .MEASURE
■
Errors and Warnings
■
HBNOISE Example
Supported Features
HBNOISE supports the following features:
■
All existing HSPICE RF noise models.
■
Uses more than one single-tone, harmonic balance to generate the steadystate solution.
■
Unlimited number of HB sources (using the same tone, possibly multiple
harmonics).
■
Includes stationary, cyclostationary, frequency-dependent, and correlated
noise effects.
■
Swept parameter analysis.
■
Results are independent of the number of HBAC sources in the netlist.
Prerequisites and Limitations
The following prerequisites and limitations apply to HBNOISE:
202
■
Requires one .HB statement (which determines the steady-state solution).
■
Requires at least one HB source or one TRANFORHB source.
■
Requires placing the parameter sweep in the .HB statement.
■
The requested maximum harmonic in .HBNOISE must be less than or equal
to half the number of harmonics used in harmonic balance (that is,
max_harm <= num_hb_harms/2).
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Multitone Harmonic Balance Noise (.HBNOISE)
Input Syntax
.HBNOISE [output] [insrc] [parameter_sweep]
+ [n1, n2, ..., nk,+/-1]
+ [listfreq=(frequencies|none|all)] [listcount=val]
+ [listfloor=val] [listsources=on|off]
Parameter
Description
output
Output node, pair of nodes, or 2-terminal element. HSPICE RF
references equivalent noise output to this node (or pair of nodes).
Specify a pair of nodes as V(n+,n-). If you specify only one node,
V(n+), then HSPICE RF assumes that the second node is ground.
You can also specify a 2-terminal element name that refers to an
existing element in the netlist.
insrc
An input source. If this is a resistor, HSPICE RF uses it as a
reference noise source to determine the noise figure. If the
resistance value is 0, the result is an infinite noise figure.
parameter_sweep Frequency sweep range for the input signal. Also referred to as the
input frequency band (IFB) or fin). You can specify LIN, DEC, OCT,
POI, SWEEPBLOCK, DATA, MONTE, or OPTIMIZE sweeps.
Specify the nsteps, start, and stop frequencies using the following
syntax for each type of sweep:
■
■
■
■
■
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LIN nsteps start stop
DEC nsteps start stop
OCT nsteps start stop
POI nsteps freq_values
SWEEPBLOCK nsteps freq1 freq2 ... freqn
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Multitone Harmonic Balance Noise (.HBNOISE)
Parameter
Description
n1,n2,...,nk,
+/-1
Index term defining the output frequency band (OFB or fout) at
which the noise is evaluated. Generally,
fout=ABS(n1*f+n2*f2+...+nk*fk+/-fin)
Where:
■
■
f1,f2,...,fk are the first through k-th steady-state tones
determined from the harmonic balance solution
fin is the IFB defined by parameter_sweep.
The default index term is [1,1,...1,-1]. For a single tone analysis, the
default mode is consistent with simulating a low-side, down
conversion mixer where the RF signal is specified by the IFB and
the noise is measured at a down-converted frequency that the OFB
specifies. In general, you can use the [n1,n2,...,nk,+/-1] index term
to specify an arbitrary offset. The noise figure measurement is also
dependent on this index term.
listfreq
Prints the element noise value to the .lis file. You can specify at
which frequencies the element noise value is printed. The
frequencies must match the sweep_frequency values defined in
the parameter_sweep, otherwise they are ignored.
In the element noise output, the elements that contribute the
largest noise are printed first. The frequency values can be
specified with the NONE or ALL keyword, which either prints no
frequencies or every frequency defined in parameter_sweep.
Frequency values must be enclosed in parentheses. For
example:listfreq=(none)
listfreq=(all)
listfreq=(1.0G)
listfreq=(1.0G, 2.0G)The default value is NONE.
listcount
204
Prints the element noise value to the .lis file, which is sorted from
the largest to smallest value. You do not need to print every noise
element; instead, you can define listcount to print the number
of element noise frequencies. For example, listcount=5 means
that only the top 5 noise contributors are printed. The default value
is 1.
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Multitone Harmonic Balance Noise (.HBNOISE)
Parameter
Description
listfloor
Prints the element noise value to the .lis file and defines a
minimum meaningful noise value (in V/Hz1/2 units). Only those
elements with noise values larger than listfloor are printed.
The default value is 1.0e-14 V/Hz1/2.
listsources
Prints the element noise value to the .lis file when the element has
multiple noise sources, such as a FET, which contains the thermal,
shot, and 1/f noise sources. You can specify either ON or OFF: ON
Prints the contribution from each noise source and OFF does not.
The default value is OFF.
Output Syntax
The HSPICE RF HB and SN noise analyses can output the output noise
(onoise), noise figures (NF, SSNF and DSNF) and, the input referred noise
(inoise). This section describes the syntax for the HBNOISE .PRINT and
.PROBE statements.
.PRINT and .PROBE Statements
.PRINT HBNOISE [ONOISE] [NF] [SSNF] [DSNF] [INOISE]
.PROBE HBNOISE [ONOISE] [NF] [SSNF] [DSNF] [INOISE]
Parameter
Description
ONOISE
Outputs the voltage noise at the output frequency band (OFB) across
the output nodes in the .HBNOISE statement. The data is plotted as a
function of the input frequency band (IFB) points. Units are in V/Hz1/2.
Simulation ignores ONOISE when applied to autonomous circuits.
NF
SSNF
NF and SSNF both output a single-side band noise figure as a function
of the IFB points:
NF = SSNF = 10 Log(SSF)
Single side-band noise factor, SSF = {(Total Noise at output, at OFB,
originating from all frequencies) - (Load Noise originating from OFB)} /
(Input Source Noise originating from IFB).
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Multitone Harmonic Balance Noise (.HBNOISE)
Parameter
Description
DSNF
DSNF outputs a double side-band noise figure as a function of the IFB
points.
DSNF = 10 Log(DSF)
Double side-band noise factor, DSF = {(Total Noise at output, at the
OFB, originating from all frequencies) - (Load Noise originating from the
OFB)} / (Input Source Noise originating from the IFB and from the
image of IFB).
INOISE
Outputs input referred noise which can be printed, probed, or
measured.
Output Data Files
An HBNOISE analysis produces these output data files:
■
Output from the .PRINT statement is written to a .printpn# file.
■
Output from the .PROBE statement is written to a .pn# file.
Both the *.printpn# and *.pn# files output data against the input frequency
band points.
■
Standard output information is written to a .lis file:
•
simulation time
•
HBNOISE linear solver method
•
HBNOISE simulation time
•
total simulation time
See also Using Noise Analysis Results as Input Noise Sources.
Measuring HBNOISE Analyses with .MEASURE
Note:
206
A .MEASURE HBNOISE statement cannot contain an expression
that uses a HBNOISE variable as an argument. Also, you cannot
use a .MEASURE HBNOISE statement for error measurement
and expression evaluation of HBNOISE.
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Multitone Harmonic Balance Noise (.HBNOISE)
The .MEASURE HBNOISE syntax supports several types of measurements:
■
Find-when
.MEASURE HBNOISE result FIND out_var1
+ AT = Input_Frequency_Band value
The previous measurement yields the result of a variable value at a specific
IFB point.
.MEASURE HBNOISE result FIND out_var1
+ WHEN out_var2 = out_var3
The previous measurement yields the result at the input frequency point
when out_var2 == out_var3.
.MEASURE HBNOISE result WHEN out_var2 = out_var3
The previous measurement yields the input frequency point when out_var2
== out_var3.
■
Average, RMS, min, max, and peak-to-peak
.MEASURE HBNOISE result [RMS] out_var [FROM = IFB1]
+ [TO = IFB2]
■
Integral evaluation
.MEASURE HBNOISE result INTEGRAL out_var
+ [FROM = IFB1] [TO = IFB2]
This measurement integrates the out_var value from the IFB1 frequency to
the IFB2 frequency.
■
Derivative evaluation
.MEASURE HBNOISE result DERIVATIVE out_var AT = IFB1
This measurement finds the derivative of out_var at the IFB1 frequency
point.
Note: .MEASURE HBNOISE cannot contain an expression that uses
an hbnoise variable as an argument. You also cannot
use .MEASURE HBNOISE for error measurement and
expression evaluation of HBNOISE.
■
Input referred noise
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Multitone Harmonic Balance Noise (.HBNOISE)
.MEASURE [HBNOISE|SNNOISE] result FIND inoise
+ AT = IFB_value
This measurement yields the result of the input referred noise at a specific
input frequency band point.
.MEASURE [HBNOISE|SNNOISE] result FIND inoise
+ WHEN out_var2 = out_var3
This measurement yields the result at the input frequency point when
out_var2 == out_var3.
.MEASURE HBNOISE result func inoise [FROM = IFB1]
+ [TO = IFB2]
Where func is one of the following measurement types:
•
AVG (average): Calculates the area under the inoise curve, divided by
the periods of interest.
•
MAX (maximum): Reports the maximum value of inoise over the
specified interval.
•
MIN (minimum): Reports the minimum value of inoise over the specified
interval.
•
PP (peak-to-peak): Reports the maximum value, minus the minimum
value of inoise over the specified interval.
•
RMS (root mean squared): Calculates the square root of the area under
the inoise curve, divided by the period of interest.
.MEASURE HBNOISE result INTEGRAL inoise
+ [FROM =IFB1] [TO = IFB2]
This measurement integrates the inoise value from the IFB1 frequency to
the IFB2 frequency.
.MEASURE HBNOISE result DERIVATIVE inoise AT = IFB1
This measurement finds the derivative of inoise at the IFB1 frequency point.
The HSPICE RF optimization flow can read the measured data from a
.MEASURE HBNOISE analysis. This flow can be combined in the HSPICE RF
optimization routine with a .MEASURE HBTR analysis (see Using .MEASURE
with .HB Analyses on page 124) and a .MEASURE PHASENOISE analysis (see
Measuring Phase Noise with .MEASURE PHASENOISE on page 172).
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Shooting Newton Noise Analysis (.SNNOISE)
Errors and Warnings
HBNOISE Errors
See the list of HBAC Errors and Warnings on page 194.
HBNOISE Example
This example performs an HB analysis, then runs an HBNOISE analysis over a
range of frequencies, from 9.0e8 to 9.2e8 Hz. Simulation outputs the output
noise at V(out) and the single side-band noise figure versus IFB, from 1e8 to
1.2e8 Hz, to the *.pn0 file. The netlist for this example is shown immediately
following.
$$*-Ideal mixer + noise source
$ prints total noise at the output (1.57156p V/sqrt-Hz),
$ single-sideband noise figure, (3.01 dB)
$ double-sideband noise figure. (0 dB)
.OPTION PROBE
.OPTION POST=2
vlo lo 0 0.0 hb 1.0 0 1 1$ Periodic, HB Input
Ilo lo 0 0
rsrc rfin rf1 1.0$ Noise source
c1 0 if q='1.0e-9*v(lo)*v(rfin)' $ mixer element
g1 0 if cur=’1.0*v(lo)*v(rfin)’ $ mixer element
rout if 0 1.0
vrf rf1 0 $ hbac 2.0 0.0
.hb tones=1.0g nharms=4 $ sweep mval 1 2 1
.HBNOISE rout rsrc lin 11 0.90g 0.92g
.print HBNOISE onoise ssnf dsnf
.probe HBNOISE onoise ssnf dsnf
.end
Shooting Newton Noise Analysis (.SNNOISE)
A SNNOISE (Shooting Newton noise) analysis simulates the noise behavior in
periodic systems. It uses a Periodic AC (PAC) algorithm to perform noise
analysis of nonautonomous (driven) circuits under periodic, steady-state tone
conditions. SNNOISE is similar to the HBNOISE analysis.
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Shooting Newton Noise Analysis (.SNNOISE)
The PAC method simulates noise assuming that the stationary noise sources
and/or the transfer function from the noise source to a specific output are
periodically modulated.
■
The modulated noise source (thermal, shot, or flicker) is modeled as a
cyclostationary noise source.
■
A PAC algorithm solves the modulated transfer function.
■
You can also use the SNNOISE PAC method with correlated noise sources,
including the MOSFET Level 9 and Level 11 models, and the behavioral
noise source in the G-element (Voltage Dependent Current Source).
You use the .SNNOISE statement to perform a Periodic Noise Analysis.
The following sections discuss these topics:
■
Supported Features
■
Input Syntax
■
Output Syntax
■
Output Data Files
■
Measuring SNNOISE Analyses with .MEASURE
■
SNNOISE Analysis Example
Supported Features
SNNOISE supports the following features:
■
All existing HSPICE RF noise models.
■
Uses Shooting Newton to generate the steady-state solution.
■
Unlimited number of sources.
■
Includes stationary, cyclostationary, frequency-dependent, and correlated
noise effects.
■
Swept parameter analysis.
■
Results are independent of the number of SNAC sources in the netlist.
Prerequisites and Limitations
The following prerequisites and limitations apply to SNNOISE:
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■
Requires one .SN statement (which determines the steady-state solution).
■
Requires at least one Periodic source. Does not recognize HB sources.
■
Requires placing the parameter sweep in the .SN statement.
Input Syntax
.SNNOISE [output] [insrc] [parameter_sweep]
+ [n1+/-1]
+ [listfreq=(frequencies|none|all)] [listcount=val]
+ [listfloor=val] [listsources=on|off]
Parameter
Description
output
Can be an output node, pair of nodes, or 2-terminal element. HSPICE RF
references the equivalent noise output to this node (or pair of nodes). Specify
a pair of nodes as V(n+,n-). If you specify only one node, V(n+), then HSPICE
RF assumes the second node is ground. You can also specify a 2-terminal
element name that refers to an existing element in the netlist.
insrc
An input source. If this is a resistor, HSPICE RF uses it as a reference noise
source to determine the noise figure. If the resistance value is 0, the result is
an infinite noise figure.
parameter_sweep Frequency sweep range for the input signal. Also referred to as the input
frequency band (IFB) or fin). You can specify LIN, DEC, OCT, POI,
SWEEPBLOCK, DATA, MONTE, or OPTIMIZE sweeps. Specify the nsteps,
start, and stop frequencies using the following syntax for each type of sweep:
■
■
■
■
■
LIN nsteps start stop
DEC nsteps start stop
OCT nsteps start stop
POI nsteps freq_values
SWEEPBLOCK nsteps freq1 freq2 ... freqn
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Parameter
Description
n1,+/-1
Index term defining the output frequency band (OFB or fout) at which the
noise is evaluated. Generally,
fout=ABS(n1*f1+/-fin)
Where:
f1 is the fundamental harmonic (tone) determined in the Shooting Newton
analysis
n1 is the associated harmonic multiplier
n1,n2,...,nk are the associated harmonic multipliers; n1 can be any nonnegative integer ≤ nharm defined in the .SN statement; +/-1 is fixed, either
+1 or -1
fin is the IFB defined by parameter_sweep.
The default index term is [1,-1]. For a single tone analysis, the default mode
is consistent with simulating a low-side, down conversion mixer where the RF
signal is specified by the IFB and the noise is measured at a down-converted
frequency that the OFB specifies. In general, you can use the [n1,+/-1] index
term to specify an arbitrary offset. The noise figure measurement is also
dependent on this index term. See Specifying Variant Indicesbelow. (See
alsoMeasuring SNNOISE Analyses with .MEASURE.)
listfreq
Prints the element noise value to the .lis file. You can specify at which
frequencies the element noise value is printed. The frequencies must match
the sweep_frequency values defined in the parameter_sweep, otherwise
they are ignored.
In the element noise output, the elements that contribute the largest noise are
printed first. The frequency values can be specified with the NONE or ALL
keyword, which either prints no frequencies or every frequency defined in
parameter_sweep. Frequency values must be enclosed in parentheses. For
example:listfreq=(none)
listfreq=(all)
listfreq=(1.0G)
listfreq=(1.0G, 2.0G)
The default value is NONE.
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Parameter
Description
listcount
Prints the element noise value to the .lis file, which is sorted from the largest
to smallest value. You do not need to print every noise element; instead, you
can define listcount to print the number of element noise frequencies. For
example, listcount=5 means that only the top 5 noise contributors are
printed. The default value is 1.
listfloor
Prints the element noise value to the .lis file and defines a minimum
meaningful noise value (in V/Hz1/2 units). Only those elements with noise
values larger than listfloor are printed. The default value is 1.0e-14 V/
Hz1/2.
listsources
Prints the element noise value to the .lis file when the element has multiple
noise sources, such as a FET, which contains the thermal, shot, and 1/f noise
sources. You can specify either ON or OFF: ON Prints the contribution from
each noise source and OFF does not. The default value is OFF.
Specifying Variant Indices
.SNNOISE is the appropriate HSPICE RF analysis for the computation of noise
at the output of a sample and hold circuit. When using .SNNOISE, you need to
specify the indices as [0,1] instead of the default [1,-1]. When you specify the
indices as [0,1], you get results that are “what you see is what you get” with
respect to the frequency sweep specified in the .SNNOISE command. There
are two more important things to consider when using .SNNOISE. You must
use enough harmonics to resolve the clock edge and you will want a high
density of SN time points. It is recommended that the number of time points be
between 2 and 20 times the number of harmonics used. To increase the density
of the time points during the .SN analysis, you can use the option DELMAX to
specify a maximum time step.
For example, you can use the following settings:
.OPTION SNACCURACY=50
.OPTION DELMAX=5p
.SN TONES=5e6 nharms=2000 trinit=800n
.SNNOISE v(vo) vsin [0,1] dec 100 1e6 1e9
This example uses 100 points per decade for the frequency sweep instead of
1000 points per decade. This is to speed up the simulation. It does not affect
the accuracy of the results.
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Shooting Newton Noise Analysis (.SNNOISE)
Output Syntax
This section describes the syntax for the SNNOISE .PRINT and .PROBE
statements.
.PRINT and .PROBE Statements
.PRINT SNNOISE [ONOISE] [NF] [SSNF] [DSNF] [INOISE]
.PROBE SNNOISE [ONOISE] [NF] [SSNF] [DSNF] [INOISE]
Parameter
Description
ONOISE
Outputs the voltage noise at the output frequency band (OFB) across
the output nodes in the .SNNOISE statement. The data is plotted as a
function of the input frequency band (IFB) points. Units are in V/Hz1/2.
Simulation ignores ONOISE when applied to autonomous circuits.
NF
SSNF
NF and SSNF both output a single-side band noise figure as a function
of the IFB points:
NF = SSNF = 10 Log(SSF)
Single side-band noise factor, SSF = {(Total Noise at output, at OFB,
originating from all frequencies) - (Load Noise originating from OFB)} /
(Input Source Noise originating from IFB).
DSNF
DSNF outputs a double side-band noise figure as a function of the IFB
points.
DSNF = 10 Log(DSF)
Double side-band noise factor, DSF = {(Total Noise at output, at the
OFB, originating from all frequencies) - (Load Noise originating from the
OFB)} / (Input Source Noise originating from the IFB and from the
image of IFB).
INOISE
214
Outputs input referred noise which can be printed, probed, or
measured.
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Output Data Files
An SNNOISE analysis produces these output data files:
■
Output from the .PRINT statement is written to a .printsnpn# file.
■
Output from the .PROBE statement is written to a .snpn# file.
Both the *.printsnpn# and *.pn# files output data against the input frequency
band points.
■
Standard output information is written to a .lis file:
•
simulation time
•
SNNOISE linear solver method
•
SNNOISE simulation time
•
total simulation time
See also Using Noise Analysis Results as Input Noise Sources.
Measuring SNNOISE Analyses with .MEASURE
Note:
A .MEASURE SNNOISE statement cannot contain an expression
that uses a SNNOISE variable as an argument. Also, you cannot
use a .MEASURE SNNOISE statement for error measurement
and expression evaluation of SNNOISE.
The .MEASURE SNNOISE syntax supports four types of measurements:
■
Find-when
.MEASURE SNNOISE result FIND out_var1
+ At = Input_Frequency_Band value
The previous measurement yields the result of a variable value at a specific
IFB point.
.MEASURE SNNOISE result FIND out_var1
+ WHEN out_var2 = out_var3
The previous measurement yields the result at the input frequency point
when out_var2 == out_var3.
.MEASURE SNNOISE result WHEN out_var2 = out_var3
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The previous measurement yields the input frequency point when out_var2
== out_var3.
■
Average, RMS, min, max, and peak-to-peak
.MEASURE SNNOISE result [RMS] out_var [FROM = IFB1]
+ [TO = IFB2]
■
Integral evaluation
.MEASURE SNNOISE result INTEGRAL out_var
+ [FROM = IFB1] [TO = IFB2]
This measurement integrates the out_var value from the IFB1 frequency to
the IFB2 frequency.
■
Derivative evaluation
.MEASURE SNNOISE result DERIVATIVE out_var AT = IFB1
This measurement finds the derivative of out_var at the IFB1 frequency
point.
Note: .MEASURE SNNOISE cannot contain an expression that uses
an hbnoise variable as an argument. You also cannot
use .MEASURE SNNOISE for error measurement and
expression evaluation of SNNOISE.
■
Input referred noise
.MEASURE SNNOISE result FIND inoise
+ AT = IFB_value
This measurement yields the result of the input referred noise at a specific
input frequency band point.
.MEASURE SNNOISE result FIND inoise
+ WHEN out_var2 = out_var3
This measurement yields the result at the input frequency point when
out_var2 == out_var3.
.MEASURE SNNOISE result func inoise [FROM = IFB1]
+ [TO = IFB2]
Where func is one of the following measurement types:
•
216
AVG (average): Calculates the area under the inoise curve, divided by
the periods of interest.
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Shooting Newton Noise Analysis (.SNNOISE)
•
MAX (maximum): Reports the maximum value of inoise over the
specified interval.
•
MIN (minimum): Reports the minimum value of inoise over the specified
interval.
•
PP (peak-to-peak): Reports the maximum value, minus the minimum
value of inoise over the specified interval.
•
RMS (root mean squared): Calculates the square root of the area under
the inoise curve, divided by the period of interest.
.MEASURE SNNOISE result INTEGRAL inoise
+ [FROM =IFB1] [TO = IFB2]
This measurement integrates the inoise value from the IFB1 frequency to
the IFB2 frequency.
.MEASURE SNNOISE result DERIVATIVE inoise AT = IFB1
This measurement finds the derivative of inoise at the IFB1 frequency point.
SNNOISE Analysis Example
This example performs an SN analysis, then runs an SNNOISE analysis over a
range of frequencies, from 9.0e8 to 9.2e8 Hz. Simulation outputs the output
noise at V(out) and the single side-band noise figure versus IFB, from 9.0e8 to
9.2e8 Hz, to the *.pn0 file. The netlist for this example is shown immediately
following.
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Periodic Time-Dependent Noise Analysis (.PTDNOISE)
*
$$*-Ideal mixer + noise source
$ prints total noise PSD at the output (2.47e-20 V^2) when q=0
$ single-sideband noise figure, (3.01 dB)
$ double-sideband noise figure. (0 dB)
.OPTION PROBE
.OPTION POST=2
vlo lo 0 0.0 cos (0 1.0 1.0g 0 0 0)
Ilo lo 0 0
rsrc rfin rf1 1.0$ Noise source
g1 0 if cur='1.0*v(lo)*v(rfin)' $ mixer element
c1 0 if q='1.0e-9*v(lo)*v(rfin)' $ mixer element
rout if 0 1.0
vrf rf1 0 $ hbac 2.0 0.0
.option delmax=0.002n
.SN tones=1G
nharms=4 trstab=10n
.SNNOISE rout rsrc lin 11 0.90g 0.92g
.probe SNNOISE onoise ssnf dsnf
.print SNNOISE onoise ssnf dsnf
.end
Periodic Time-Dependent Noise Analysis (.PTDNOISE)
While HBNOISE and SNNOISE calculate a time-averaged power spectral
density, there are applications where a characterization of the timedependence of the noise is required. These applications include computation of
jitter associated with a noisy signal crossing a threshold and computation of the
noise associated with discretization of an analog signal, which computes the
noise in a periodically driven circuit at a point in time. Periodic Time-Dependent
noise analysis (PTDNOISE) calculates the noise spectrum and the total noise
at a point in time. Jitter in a digital threshold circuit can then be determined from
the total noise and the digital signal slew rate.
Circuits driven by large periodic signals produce cyclostationary noise, that is,
the noise characteristics are periodic in time. Cyclostationary noise can be
characterized in several ways, with the particular application determining which
is appropriate.[9] The time-average power spectral density (PSD) ignores
frequency correlations in the noise, but is adequate when the fundamental
frequency of the cyclostationary noise is much larger than the bandwidth of
interest. The time-average PSD is calculated in the HBNOISE/SNNOISE
analyses. [10]
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Periodic Time-Dependent Noise Analysis (.PTDNOISE)
The harmonic power spectral density (HPSD) or equivalently, the autocorrelation function, R(t1,t2), contains the correlation information between
noise sidebands that is necessary to build behavioral cyclostationary noise
sources and to separate the amplitude modulation (AM) and phase modulation
(PM) noise components. (See Amplitude Modulation/Phase Modulation
Separation for more information.
The time-dependent power spectral density (TDPSD) can be integrated over
frequency to yield the time-dependent noise (TDN). TDN can then be used to
determine jitter associated with a noisy signal crossing a threshold. PTDNOISE
analysis allows the calculation of TDPSD, TDN, and jitter. In addition, you can
calculate both the time-domain power spectral density (TDSN) and the
integrated noise (time-dependent noise, TDN) at multiple time points.
By measuring the jitter associated with a noisy signal crossing a threshold, jitter
is modeled by displacing the time in a noise free signal v(t) with a stochastic
process j(t).
Equation 43
V jitter ( t ) = v ( t + j ( t ) )
We can also determine the voltage at this node including the time-dependent
noise n(t):
Vn ( t ) = v ( t ) + n ( t )
by equating these two representations, expanding in a Taylor series, and
dropping higher order terms, as follows:
Equation 44
Equation 45
V ( t ) + n ( t ) = v ( t + j ( t ) ) = v ( t ) + dv ( t ) ⁄ dt ⋅ j ( t ) + …
N ( t ) = dv ( t ) ⁄ dt ⋅ j ( t )
In terms of variances, jitter is then defined as:
Equation 46
2
Var ( j ( t ) ) = n ( t ) ⁄ ( dv ( t ) ⁄ dt )
The following sections discuss these topics:
Equation 47
2
■
PTDNOISE Input Syntax
■
PTDNOISE Output Syntax and File Format
■
Error Handling and Warnings
■
Usage Example
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PTDNOISE Input Syntax
.PTDNOISE output time_value [time_delta]
+ frequency_sweep
+ [listfreq=(frequencies|none|all)]
+ [listcount=val] [listfloor=val]
+ [listsources=on|off]
Parameter
Description
output
Is an output node, pair of nodes, or 2-terminal elements. HSPICE RF
references the equivalent noise output to this node (or pair of nodes). Specify
a pair of nodes as V(n+,n-); only one node as V(n+, n-). If you specify only one
node, V(n+), then HSPICE RF assumes the second node is ground. You can
also specify a 2-terminal element name that refers to an existing element in
the netlist.
time_value
Time point at which time domain noise is evaluated. Specify either a time point
explicitly, such as: TIME=value, where value is either numerical or a
parameter name or a .MEASURE name associated with a time domain
.MEASURE command located in the netlist. PTDNOISE uses the time point
generated from the .MEASURE command to evaluate the noise
characteristics. This is useful if you want to evaluate noise or jitter when a
signal reaches some threshold value.
time_delta
Time point at which time domain noise is evaluated. Specify either a time point
explicitly, such as: TIME=value, where value is either numerical or a
parameter name or a .MEASURE name associated with a time domain
.MEASURE command located in the netlist. PTDNOISE uses the time point
generated from the .MEASURE command to evaluate the noise
characteristics. This is useful if you want to evaluate noise or jitter when a
signal reaches some threshold value.
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Parameter
Description
frequency_sweep Frequency sweep range for the output noise spectrum. The upper and lower
limits also specify the integral range in calculating the integrated noise value.
Specify LIN,DEC, OCT, POI, SWEEPBLOCK, DATA sweeps. Specify the
nsteps, start, and stop frequencies using the following syntax for each type of
sweep:
■
■
■
■
■
listfreq
LIN nsteps start stop
DECnsteps start stop
OCT nsteps start stopPOI nsteps freq_values
SWEEPBLOCK nsteps freq1 freq2 ... freqn
DATA data_name
Prints the element noise value to the .lis file. This information is only printed if
a noise spectrum is requested in a PRINT or PROBE statement. (See
PTDNOISE Output Syntax and File Format.) You can specify which
frequencies the element noise is printed. The frequencies must match the
sweep_frequency values defined in the frequency_sweep, otherwise they are
ignored.
In the element noise output, the elements that contribute the largest noise are
printed first. The frequency values can be specified with the NONE or ALL
keyword, which either prints no frequencies or every frequency defined in
frequency_sweep. Frequency values must be enclosed in parentheses. For
example:
■
listfreq=(none)
listfreq=(all)
■
listfreq=(1.0)
■
listfreq=(1.0G, 2.0G)
The default value is NONE.
■
listcount
Prints the element noise value to the .lis file, which is sorted from the largest
to smallest value. You do not need to print every noise element; instead, you
can define listcount to print the number of element noise frequencies. For
example, listcount=5 means that only the top 5 noise contributors are
printed. The default value is 1.
listfloor
Prints the element noise value to the .lis file and defines a minimum
meaningful noise value (in V/Hz1/2 units). Only those elements with noise
values larger than listfloor are printed. The default value is 1.0e-14 V/Hz1/
2
.
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Parameter
Description
listsources
Prints the element noise value to the .lis file when the element has multiple
noise sources, such as a MOSFET, which contains the thermal, shot, and 1/f
noise sources. You can specify either ON or OFF: ON prints the contribution
from each noise source and OFF does not. The default value is OFF.
PTDNOISE Output Syntax and File Format
PTDNOISE output syntax allows for the output of a single parameter: onoise,
where, onoise is the noise voltage spectral density at each frequency point
specified by the frequency_sweep keyword for the time points specified by the
TIME keyword. The units are V Hz .
.PROBE PTDNOISE onoise
.PRINT PTDNOISE onoise
Parameter Units
Description
onoise
Noise voltage spectral density at each frequency point specified
by frequency_sweep at the time point specified by time_value
V Hz
Output File Format
The following PTDNOISE output files are generated depending on the user
input:
222
File
Description
*.printptn#
Writes output from the .PRINT statement when using HB to obtain the
steady state solution
*.ptn#
Writes output from the .PROBE statement when using HB to obtain
the steady state solution
*.printsnptn#
Reports output from the .PRINT statement when using SN to obtain
the steady state solution.
*.snptn#
Writes output from the .PROBE statement when using SN to obtain
the steady state solution.
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File
Description
*.lis
Standard output file *.lis contains the following information:
■
■
■
■
■
■
■
■
■
■
■
Performance Statistics Log
Number of Nodes
Number of FFT Points
Number of Equations
Memory in use
Maximum Krylov iterations
Maximum Krylov Dimension
Target GMRES Residual
Gmres Residual
Actual Krylov Iterations taken
Frequency (swept input frequency values)
Noise source contributions are listed sequentially and are controlled
by the PTDNOISE command line parameters: listtime, listfreq,
listcount, listfloor, and listsources.
.MEASURE Syntax and File Format
The syntax for .MEASURE PTDNOISE is:
.MEASURE PTDNOISE result [integnoise|jitter|slewrate]
.MEASURE PTDNOISE allows for the measurement of these parameters:
integnoise, time-point, tdelta-value, slewrate, and strobed jitter.
Parameter
Units Description
integnoise
V
slewrate
v/sec Output signal slewrate at the time point specified by
TIME=val.
jitter
sec
Note:
Voltage noise integrated over a frequency range specified
by frequency_range at the time point specified by TIME=val.
Calculated from the noise voltage (integrated over the
frequency range specified by frequency_range), divided by
the slew rate at the same node(s), at the time point specified
by TIME=val.
.MEASURE PTDNOISE is ignored when a TIME=sweep is
specified in the netlist and a warning message is issued.
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Periodic Time-Dependent Noise Analysis (.PTDNOISE)
Measure File Format
File
Description
*.msnptn#
Contains output from the .MEASURE statement when using .SN to
obtain the steady state solution.
Error Handling and Warnings
Error messages are generated under the following circumstances:
■
PTDNOISE frequency sweep includes negative frequencies. PTDNOISE
allows only frequencies that are greater than or equal to zero.
■
PTDNOISE time sweep includes negative times. PTDNOISE allows only
time points that are greater than or equal to zero.
■
No SN statement is specified (error at parser). PTDNOISE requires an SN
statement to generate the steady-state solution.
■
Incorrect match to .MEASURE statement.
A warning is issued for a PTDNOISE convergence failure. When the gmres
solver reaches the maximum number of iterations and the residual is greater
than the specified tolerance, PTDNOISE generates a warning and then
continue as if the data were valid. The Warning reports the following
information:
■
Final GMRES Residual
■
Target GMRES Residual
■
Maximum Krylov Iterations
■
Actual Krylov Iterations taken
Usage Example
The following test case illustrates the PTDNOISE analysis for a simple inverter.
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Periodic Time-Dependent Noise Analysis (.PTDNOISE)
* Simple RC + Inverter - rcInvPTDNoise.sp
* rrd Jan 03, 2007
* Simulates PSD(t,f) of a simple inverter
* sweep time points
.param f0 = 5.0e8
.sn tones=f0 nharms=4 trinit=10n
.PTDNOISE v(out1) TIME=lin 3 0 2n TDELTA=.1n dec 5 1e5 1e10
+ listfreq=(1e6,1e8)
+ listcount=1
+ listsources=ON
.MEASURE PTDNOISE strobejit STROBEJITTER onoise FROM = 1e4 TO =
1e10
$.measure SN t1 trig AT=0 targ v(out1) val=1.5 fall=1
.opt post
.probe ptdnoise onoise
.print ptdnoise onoise
.probe sn v(out1)
vd
vdd 0
3.0
.global vdd
vgate in0 0
COS(1.5 1.4 'f0'
rin
in0 in1 50
rout out1 0
.1g
0 0 0)
xo1 in1 out1 inv
.subckt inv in out
m1 out in 0 0 n l=350e-9 w=4.5e-6
m2 out in vdd vdd p l=350e-9 w=4.5e-6
.ends
.MODEL N NMOS
+Level= 49 Tnom=27.0 version =3.1 TLEVC= 1
*
***
.MODEL P PMOS
+Level= 49 Tnom=27.0 version =3.1 TLEVC= 1
.end
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Multitone Harmonic Balance Transfer Function Analysis (.HBXF)
Multitone Harmonic Balance Transfer Function
Analysis (.HBXF)
The .HBXF command calculates the transfer function from a given source in
the circuit to a designated output. Frequency conversion is calculated from the
input frequencies to a single output frequency that is specified with the
command. The relationship between the .HBXF command and the input/output
is expressed in the following equation:
Equation 48
Y m ( jω0 ) =
∑ HBXFm,n ( jω0 ,j ( ω + Δω) ) ⋅
X n ( j ( ω + Δω) )
ωε W
Where:
■
HBXF m ,n ( jω0 ,j ( ω + Δω) ) is the transfer function from input port n to the
output port m
■
W is the set of all possible harmonics
■
ω + Δω is the input frequency
■
Δω is the offset frequency
■
m is the output node number
■
n is the input node number
■
ω0 is the output frequency
■
Y is the output (voltage or current)
■
X is the input (voltage or current)
The following sections discuss these topics:
226
■
Supported Features
■
Input Syntax
■
Output Syntax
■
Output Data Files
■
Example
■
HBXF Test Listing
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Multitone Harmonic Balance Transfer Function Analysis (.HBXF)
Supported Features
The .HBXF command supports the following features:
■
All existing HSPICE RF models and elements
■
Sweep parameter analysis
■
Unlimited number of HB sources
Prerequisites and Limitations
The following prerequisites and limitations apply to the .HBXF command:
■
Only one .HBXF statement is required. If you use multiple .HBXF
statements, HSPICE RF only uses the last .HBXF statement.
■
At least one .HB statement is required, which determines the steady-state
solution.
■
Parameter sweeps must be placed in .HB statements.
Input Syntax
.HBXF out_var freq_sweep
Parameter
Description
out_var
Specify i(2_port_elem) or V(n1[,n2])
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Multitone Harmonic Balance Transfer Function Analysis (.HBXF)
Parameter
Description
freq_sweep
Frequency sweep range for the input signal (also referred to as the
input frequency band (IFB or fin)). A sweep of type LIN, DEC, OCT,
POI, or SWEEPBLOCK. Specify the nsteps, start, and stop
frequencies using the following syntax for each type of sweep:
■
■
■
■
■
LIN nsteps start stop
DEC nsteps start stop
OCT nsteps start stop
POI nsteps freq_values
SWEEPBLOCK = BlockName
Specify the frequency sweep range for the output signal. HSPICE
RF determines the offset frequency in the input sidebands; for
example,
f1 = abs(fout - k*f0) s.t. f1<=f0/2
The f0 is the steady-state fundamental tone, and f1 is the input
frequency.
Output Syntax
This section describes the syntax for the HBXF .PRINT and .PROBE
statements.
.PRINT and .PROBE Statements
.PRINT HBXF TYPE (NODES | ELEM)
.PROBE HBXF TYPE (NODES | ELEM)
Parameter
Description
TYPE
TYPE can be one of the following:
■
■
TFV = existing source
TFI = placeholder value for the current source
attached to the given node.
The transfer function is computed on the output
variables and input current or voltage.
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Multitone Harmonic Balance Transfer Function Analysis (.HBXF)
Parameter
Description
NODES | ELEM
NODES or ELEM can be one of the following:
■
■
■
Voltage type – a single node name (n1), or a pair
of node names, (n1,n2)
Current type – an element name (elemname)
Power type – a resistor (resistorname) or port
(portname) element name.
Output Data Files
An HBXF calculation produces these output data files:
■
Output from the .PRINT statement is written to a .printxf# file.
•
The output is in ohms, siemens, or undesignated units, and the header
in the output file is Z(..). Y(..) or GAIN(..).
■
Output from the .PROBE statement is written to an .xf# file.
■
Reported performance log statistics are written to a .lis file:
•
HBXF CPU time
•
HBXF peak memory usage
Example
Based on the HB analysis, the following example computes the transimpedance from isrc to v(1).
.hb tones=1e9 nharms=4
.hbxf v(1) lin 10 1e8 1.2e8
.print hbxf tfv(isrc) tfi(n3)
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Shooting Newton Transfer Function Analysis (.SNXF)
HBXF Test Listing
* Test HBXF: nonlinear order-2 poly equation
.OPTIONS PROBE
.OPTIONS POST=2
vlo lo 0 cos(0 1.0 1g 0 0) tranforhb=1
rlo lo 0 50
vrf1 rf1 0 0
rrf1 rf1 0 50
E1 out 0 POLY(2) lo 0 rf1 0 0 1 1 1 10 1
rout out 0 50
.hb tones=1g nharms=5
.hbxf v(out) lin 2 100meg 200meg
.print hb v(out) v(rf1) v(lo)
.print hbxf tfv(vrf1) tfv(vlo)
.end
Shooting Newton Transfer Function Analysis (.SNXF)
The .SNXF command calculates transfer functions from an arbitrary number of
small signal sources to a designated output in a circuit under periodic steady
state conditions. Frequency conversion is calculated from multiple input
frequencies to a single output at a single frequency that is specified on the
command line.
Prerequisites and Limitations
The following prerequisites and limitations apply to the .SNXF command:
■
Only one .SNXF statement is required. If you use multiple .SNXF
statements, HSPICE RF only uses the last one issued.
■
At least one .SN statement is required, which determines the steady-state
solution.
■
Parameter sweeps must be placed in .SN statements.
The following sections discuss these topics:
230
■
Input Syntax
■
Output Syntax
■
Output Data Files
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Chapter 8: Large Signal Periodic AC, Transfer Function, and Noise Analyses
Shooting Newton Transfer Function Analysis (.SNXF)
■
Example
■
SNXF Test Listing
Input Syntax
.SNXF out_var freq_sweep
Parameter Description
Parameter
Description
out_var
Specify i(2_port_elem) or V(n1[,n2])
freq_sweep
Frequency sweep range for the input signal (also referred to as the
input frequency band (IFB or fin)). A sweep of type LIN, DEC, OCT,
POI, or SWEEPBLOCK. Specify the nsteps, start, and stop
frequencies using the following syntax for each type of sweep:
■
■
■
■
■
LIN nsteps start stop
DEC nsteps start stop
OCT nsteps start stop
POI nsteps freq_values
SWEEPBLOCK = BlockName
Specify the frequency sweep range for the output signal. HSPICE
RF determines the offset frequency in the input sidebands Fin,
where Fin = abs(n*F0 +/- Fout). F0 is the steady-state fundamental
tone, and Fout is the output frequency. SNXF then generates the
transfer functions from all of the input sidebands (the Fin values) to
the output frequency Fout.
Output Syntax
This section describes the syntax for the SNXF .PRINT and .PROBE
statements.
.PRINT and .PROBE Statements
.PRINT SNXF TYPE(NODES | ELEM)
.PROBE SNXF TYPE(NODES | ELEM)
Parameter Description
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Shooting Newton Transfer Function Analysis (.SNXF)
TYPE can be one of the following:
■
TFV = existing source
■
TFI = placeholder value for the current source attached to the given node.
The transfer function is computed on the output variables and input current or
voltage .NODES | ELEM NODES or ELEM can be one of the following:
■
Voltage type – a single node name (n1), or a pair of node names, (n1,n2)
■
Current type – an element name (elemname)
■
Power type – a resistor (resistorname) or port (portname) element name
Output Data Files
An SNXF calculation produces these output data files:
■
Output from the .PRINT statement is written to a .printsnxf# file. The output
is in ohms, siemens, or undesignated units, and the header in the output file
is Z(..). Y(..) or GAIN(..).
■
Output from the .PROBE statement is written to a .snxf# file.
Reported performance log statistics are written to a .lis file:
■
SNXF CPU time
■
SNXF peak memory usage
Example
Based on the SN analysis, the following example computes the
transimpedance from isrc to v(1).
.SN tones=1e9 nharms=4
.SNXF v(1) lin 10 1e8 1.2e8
print SNXF TFV(isrc) TFI(n3)
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Chapter 8: Large Signal Periodic AC, Transfer Function, and Noise Analyses
Shooting Newton Transfer Function Analysis (.SNXF)
SNXF Test Listing
* Test SNXF: nonlinear order-2 poly equation
.OPTIONS PROBE
.OPTIONS POST=2
vlo lo 0 cos(0 1.0 1g 0 0)
rlo lo 0 50
vrf1 rf1 0 0
rrf1 rf1 0 50
E1 out 0 POLY(2) lo 0 rf1 0 0 1 1 1 10 1
rout out 0 50
.opt delmax=.01n
.sn tones=1g nharms=5
.snxf v(out) lin 2 100meg 200meg
.print sn v(out) v(rf1) v(lo)
.print snxf tfv(vrf1) tfv(vlo)
.end
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Chapter 8: Large Signal Periodic AC, Transfer Function, and Noise Analyses
References
References
[1] S. Maas, Nonlinear Microwave Circuits, Chapter 3, IEEE Press, 1997.
[2] R. Gilmore and M.B. Steer, “Nonlinear Circuit Analysis Using the Method of
Harmonic Balance - A Review of the Art, Part I, Introductory Concepts.”
International Journal of Microwave and Millimeter-wave Computer-Aided
Engineering, Volume 1, No. 1, pages 22-37, 1991.
[3] R. Gilmore and M.B. Steer, “Nonlinear Circuit Analysis Using the Method of
Harmonic Balance - A Review of the Art. Part II. Advanced Concepts.”
International Journal of Microwave and Millimeter-wave Computer-Aided
Engineering, Volume 1, No. 2, pages 159-180, 1991.
[4] V. Rizzoli, F. Mastri, F. Sgallari, G. Spaletta, “Harmonic-Balance Simulation
of Strongly Nonlinear Very Large-Size Microwave Circuits by Inexact
Newton Methods,” MTT-S Digest, pages 1357-1360, 1996.
[5] S. Skaggs, Efficient Harmonic Balance Modeling of Large Microwave
Circuits, Ph.D. thesis, North Carolina State University, 1999.
[6] R.S. Carson, High-Frequency Amplifiers, 2nd Edition, John Wiley & Sons,
1982
[7] S.Y. Liao, Microwave Circuit Analysis and Amplifier Design, Prentice-Hall,
1987.
[8] Y. Saad, Iterative Methods for Sparse Linear Systems, PWS Publishing
Company, 1995.
[9] J. Roychowdhury, D. Long, and P. Feldmann, “Cyclostationary Noise
Analysis of Large RF Circuits with Multitone Excitations,” IEEE Journal of
Solid-State Circuits, volume 33, pages 324–336, March 1998.
[10] A. Demir, A. Sangiovanni-Vincentelli, “Analysis and Simulation of Noise in
Nonlinear Electronic Circuits and Systems”, Kluwer Academic, 1998.
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9
Transient Noise Analysis
9
Describes the HSPICE and HSPICE RF solutions to perform transient noise
analysis and compute noise statistics and their variation over time for circuits
driven with non-periodic waveforms.
Transient noise analysis shows the effect of noise on the signal magnitude. It is
also useful to see how noise effects the timing of the signal. From the transient
noise analysis results, jitter can be measured. The two jitter measurements are
time interval error (TIE) and autocorrelation function. TIE measures the timeshift behavior relative to a reference signal. The autocorrelation function is used
for tracking the relative time-shift behavior of the signal.
The chapter describes two approaches:
■
Monte Carlo (default), where the device noise is modeled as uncorrelated
random signal sources to predict the statistical characteristics of the circuit
performance due to device noise.
■
Stochastic Differential Equation (SDE), for advanced users, which makes a
direct prediction of the actual statistics of the output waveforms.
HSPICE and HSPICE RF include several different algorithms for understanding
circuit behavior based on noise generated internally by electronic devices and
thermal noise. PHASENOISE analysis computes the effects noisy elements
have on the output spectrum of oscillators. HBNOISE and SNNOISE analyses
compute the small-signal variations that noise can create about large-signal
steady-state operating conditions. Periodic time-domain noise (PTDNOISE)
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Chapter 9: Transient Noise Analysis
Overview of HSPICE/HSPICE RF Transient Noise Analysis
analysis computes the noise statistics of a periodic signal, and how those
statistics vary with time over the period of the steady-state signal.
Table 12
.TRANNOISE Analysis Supported Platforms
Linux RHEL
Linux SUSE
Sun
Windows
Yes
Yes
Yes
Yes
The following topics are discussed in these sections:
■
Overview of HSPICE/HSPICE RF Transient Noise Analysis
■
Modeling Frequency-Dependent Noise Sources
■
Monte Carlo Noise Analysis
■
Stochastic Differential Equation (SDE) Analysis
■
Setting up a .TRANNOISE Analysis
■
Jitter Measurements from .TRANNOISE Analysis Results
■
Correlating Noise Results: .TRANNOISE (Monte Carlo) and .NOISE
■
Error Handling, Error Recovery, Status Reporting
■
References
Overview of HSPICE/HSPICE RF Transient Noise
Analysis
A variety of noise measurements are desirable from circuit simulation. The
traditional SPICE .noise analysis provides a measurement of the RMS noise
voltage at an output node as a function of frequency. This RMS value is akin to
a measurement of the standard deviation of an equivalent Gaussian distribution
of noise present at the output node of interest due to the contributing random
noise sources within the circuit. The .noise analysis is a small-signal analysis
giving an output noise (onoise) value over the .ac frequency range. More
advanced examples of noise measurements include Phase Noise and Timing
Jitter. Timing Jitter, in particular, is a measurement of a clock or oscillator's
random noise over a time interval. It represents the standard deviation (or
variance) of the timing uncertainty (i.e. the random drift of the clock edges) as a
function of time. It is therefore a time-domain noise measurement that is
typically evaluated at each cycle or half-cycle. For some clocks, oscillators, and
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Overview of HSPICE/HSPICE RF Transient Noise Analysis
PLLs, this measurement can be separated into time-independent and timedependent contributions, and written as
Equation 49
22
σ ( τ ) = ---------[ R φ( 0 ) – R φ( τ ) ]
2
ω0
2
where σ ( τ ) represents the time-dependent variance, τ is the time advance,
and R φ( τ ) is the autocorrelation function related to the power spectrum of
phase variations as
Equation 50
1
R φ( τ ) = -----2π
∞
∫ Sφ ( ω)e
jωτ
dω
–∞
These special relationships allow the computation of timing jitter from the
results of .phasenoise analysis, since we can assume L ( f ) ≅ S φ( f ) , and
therefore derive the time-varying noise from the frequency-domain phase noise
simulation solution.
Other measurements of time-dependent or time-varying noise are also
desirable for circuits other than clocks and oscillators, and for situations other
than steady-state operation. The purpose of such measurements is usually
similar: derive useful information on the time-varying statistical behavior of the
circuit due to its internal noise sources.
Transient Noise Analysis is essentially a typical .TRAN simulation, but with all
random noise sources within the circuit activated as contributing signal
sources. Monte Carlo Noise analysis is a transient noise simulation approach
that uses uncorrelated random signal sources for device noise in such a way
that all noise signals can be seeded uniquely but repeatable from run-to-run to
predict the statistical characteristics of circuit performance due to device noise.
The resulting outputs are typically examined using histogram plots to measure
the statistical behavior.
Techniques Available in HSPICE
HSPICE provides the following techniques for transient noise analysis:
1. Single-run Monte Carlo: (default) A single transient analysis that includes
time-varying noise contributions to all output waveforms. With ergodic
systems, the statistics of output variables are observable over time.
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Chapter 9: Transient Noise Analysis
Modeling Frequency-Dependent Noise Sources
2. Multi-run Monte Carlo: Multiple transient analyses, each including timevarying noise, with unique seeding from run to run, form an ensemble of
simulations. Output waveform statistics are observable across the ensemble
at specific time points. For techniques 1 and 2 see Monte Carlo Noise
Analysis.
3. Stochastic Differential Equation (SDE) Dynamic noise statistics are
computed in the form of a time-varying covariance matrix. SDE techniques
allow the output of a variance waveform for any output signal. Variance
waveforms can be used to construct probability density plots. See
Stochastic Differential Equation (SDE) Analysis.
Single-run Monte Carlo features include:
■
Simulation includes statistically accurate noise source contributions from all
devices.
■
Adjustable bandwidth for noise source frequency responses.
■
Fastest approach possible; based on single .TRAN analysis.
■
Effective for ergodic simulations (viewing statistical variations over time).
■
Use the following process for Single Monte Carlo Trannoise analysis
•
Run as typical .TRAN analysis.
•
Post process waveforms to measure resulting noise effects.
•
Use FMIN to set low-frequency flicker noise limits.
•
Use FMAX to set maximum noise source waveform bandwidth and
ensure Nyquist sampling.
•
Vary seed values to re-run simulations with uniquely different noise
waveforms.
SDE and Multi-run Monte Carlo approaches are useful for characterizing
statistics at specific time events.
■
SDE approach gives probability density information.
■
Multi-run Monte Carlo provides data ensembles for histogram generation.
Modeling Frequency-Dependent Noise Sources
Transient noise techniques require that noise sources be modeled in the time
domain. These techniques model device noise sources in terms of standard
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Chapter 9: Transient Noise Analysis
Monte Carlo Noise Analysis
white Gaussian noise processes. Let the standard white Gaussian noise
process be written as ζ ( t ) .
White noise source models can be calculated in terms of intensity functions.
For example, if the (frequency dependent) noise from a time varying
conductance is given by
Equation 51
2
i n = 4kTG ( t )Δf
...then this can be modeled in terms of intensity as the random time-domain
current given by
Equation 52
jn =
2kTG ( t )ζ ( t )
In the case of flicker noise, it is necessary to create the 1/f power spectrum of
flicker noise sources by filtering a ζ ( t ) process. This can be accomplished with
the following rational function transfer relationship:
N
Equation 53
H(s) =
( s + ωzi )
∏ (------------------s + ωpi )
i =1
Note that since all flicker sources can be modeled over the same frequency
range (i.e., bandwidth), this same transfer function can be used for all sources.
Tests have shown that the above fit is very accurate using one pole/zero per
octave, and with reasonable fits using one pole/zero for every two octaves, or
even with one pole/zero per decade. This fitting algorithm is therefore
frequency range-specific, which is why the parameters FMAX and FMIN are
used for specifying frequency ranges for Transient Noise Analysis similarly to
the modeling of the frequency-dependent S-element.
Monte Carlo Noise Analysis
You can use two methods of Monte Carlo analysis to determine transient noise,
single-sample (default) and multiple-sample:
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Chapter 9: Transient Noise Analysis
Monte Carlo Noise Analysis
Single-sample Monte Carlo method:
■
Using single-sample Monte Carlo method
■
Single transient analysis
■
Time-varying noise contributes to all output variables
■
Assuming the circuit is ergodic*, the statistics of output variables are
observable over time
■
With post-processing, results can be shown as TIE (Timing Interval Error)
jitter and jitter spectrum
* Ergodic – relating to a process in which every sequence or sizable sample is
equally representative of the whole.
Multiple-sample Monte Carlo method:
■
Multiple transient analyses
■
An ensemble of simulations is created, with enough samples to adequately
observe the output waveform statistics due to noise
■
Results are shown as histogram of statistical behavior
The equations for Monte Carlo transient noise analysis define the Monte Carlo
approach:
Let the time-domain system of equations for transient analysis be given by the
MNA system described by the following vector state equation:
f ( x·, x, t ) = 0
Consider this the noise-less system that is solved during a normal transient
analysis. Transient noise analysis can be considered a similar analysis where
we now inject noise from all device noise models to give the modified equation:
Equation 54
Equation 55
f ( x·, x, t ) = – j n ( t )
This system reflects the additional noise sources added and can be solved in
the same manner as transient analysis. However, if we consider each noise
source to be related to a white Gaussian noise function, it is clear that we must
create an ensemble of waveforms for our unknown x(t) vector in order to
predict the statistics of the outputs. This type of simulation therefore involves
generating multiple uncorrelated noise source waveforms for all noise sources,
and then running multiple simulations in a Monte Carlo fashion.This approach
is also known as Monte-Carlo Noise Simulation. This method cannot directly
measure the statistics of output signals due to input noise (as with .NOISE), but
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Chapter 9: Transient Noise Analysis
Stochastic Differential Equation (SDE) Analysis
instead models noise sources as independent time-domain stimuli. Generating
statistical information in this approach requires running a plurality of
simulations over a variety of random noise-source sequences (to create an
ensemble of output waveforms) and then analyzing the statistics of the
ensemble using histograms of other plots. When the system behavior can be
considered ergodic, it is possible to run a single very long duration simulation
in order to capture the statistical variations of the output signal over time (as
with an eye-diagram). Monte-Carlo modeling of the noise sources can be done
with a sum of sinusoids with random phases [2], or using random number
generators with the appropriate statistical distributions[3]. An advantage of the
Monte-Carlo approach is its ability to capture very nonlinear noise behaviors.
This is useful, for example, when the responses of circuits with noise are known
to have non-Gaussian variations about their noise-less simulations.
Stochastic Differential Equation (SDE) Analysis
Transient Noise Analysis is very useful for predicting waveform statistics at
particular time points. One method to accomplish this is to run the multi-sample
Monte Carlo approach, and then use the ensemble of simulation results to
generate histograms at the time points of interest. Histograms that measure
vertical distributions reveal voltage noise. Histograms that measure horizontal
time-shift distributions reveal jitter. In those cases where it is desirable to have a
very accurate distribution curve, it may be necessary to simulate with a large
number of Monte Carlo samples. SDE analysis can provide a more efficient
alternative in such cases. Instead of requiring a large ensemble of results, SDE
performs special calculations that directly predict the statistics of the output
waveforms.
Let the time-domain signal resulting from a regular transient analysis (i.e., with
s
noise ignored) for a specific output node be written as v out ( t ) .
Let the time-domain signal resulting from an analysis with signal and noise for
s+n
the same output node be written as v out ( t ) .
s
We can define the noise voltage component v out ( t ) to be:
Equation 56
n
v out ( t ) = v
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s+n
out
s
( t ) – v out ( t )
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Chapter 9: Transient Noise Analysis
Stochastic Differential Equation (SDE) Analysis
We can define a variance equal to the expected value of this noise component
at a given time to be:
Equation 57
2
n
n
σn ( t ) = vout ( t ) ⋅ vout ( t )
If we assume that the noise variations are small, we can create a linear
Stochastic Differential Equation (SDE) for the noise contribution vector x n( t )
n
(on entry in the vector being the output noise v out ( t ) ). This SDE may be
formulated in terms of time-varying coefficient matrices that are evaluated for a
normal transient analysis, which are functions of the noise-free solution vector
x s ( t ) and derived from the noise-free transient analysis computations [1]:
Equation 58
A ( t )x n + C ( t )x·n + B ( t )v ≅ 0
x n ( 0 ) = x n, 0
We can then create and solve a linear ordinary differential equation (ODE)
T
system for the time-varying noise correlation matrix K ( t ) = x n ( t )x n ( t ) :
Equation 59
·
T
K ( t ) = E ( t )K ( t ) + F ( t )F ( t )
where E ( t ) and F ( t ) are derived from A ( t ) , B ( t ) , and C ( t ) , and T indicates
the transpose operation.
In general, simultaneously solving for both the deterministic and stochastic
differential equations can therefore give us the complete time-dependent output
signal waveform vector x s ( t ) , as well as the complete time-varying noise
T
correlation/covariance matrix K ( t ) = x n ( t )x n ( t ) . The entries in this matrix
2
n
represent time-dependent variance values σn ( t ) for output signals v out ( t ) .
This output can be interpreted and plotted as a time-varying RMS noise voltage
n
2
waveforms for v RMS( t ) = σn ( t ) . The results of such a transient + noise
analysis include the usual deterministic transient analysis waveforms, including
s
the mean voltage output v out ( t ) , and also its (stochastic) time-varying RMS
n
noise component v RMS( t ) . In this sense, the SDE analysis method provides
typical SPICE output waveforms for circuit unknowns, plus the additional
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Setting up a .TRANNOISE Analysis
waveform representing the time-varying statistics of the circuit. The
.TRANNOISE SDE method therefore activates this special analysis and makes
this output available to the user.
Setting up a .TRANNOISE Analysis
The transient noise analysis requires an accompanying .tran analysis which
determines the time-sampling, matrix solutions, and deterministic output
waveforms. The .TRANNOISE command is used to activate transient noise and
to compute the additional noise variables. Note that this is consistent with how
.NOISE computes additional noise outputs when added to an .AC analysis.]
The following sections discuss these topics:
■
Input Syntax
■
Monte Carlo Output Data
■
SDE Output Data
■
Monte Carlo Examples
■
SDE Examples
Input Syntax
Monte Carlo Single Sample Approach
.TRANNOISE output [METHOD=MC] [SEED=val]
+ [AUTOCORRELATION=0|1|off|on]
+ [FMIN=val] [FMAX=val] [SCALE=val]
Monte Carlo Multi-Sample Approach
.TRANNOISE output
+ [METHOD=MC] [SEED=val] [SAMPLES=val]
+ [AUTOCORRELATION=0|1|off|on]
+ [FMIN=val][FMAX=val][SCALE=val]
SDE Approach
.TRANNOISE output METHOD=SDE
+ [AUTOCORRELATION=0|1|off|on|]
+ [TIME=(all|val)]
+ [FMIN=val] [FMAX=val] [SCALE=val]
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Keyword
Description
output
(Required) Output node, pair of nodes, or 2-terminal element. Noise
calculations are referenced to this node (or node pair). Specify a pair of
nodes as V(n+,n-). If you specify only one node, V(n+), then HSPICE RF
reads the second node as ground. If you specify a 2-terminal element,
the noise voltage across this element is treated as the output.
METHOD=MC | SDE
Specifies Monte Carlo or SDE transient noise analysis method. The
default, or, if METHOD is not specified, is the single-sample Monte Carlo
method. Specifying METHOD=SDE is required to select the transient
noise analysis SDE method. METHOD=MC | SDE is position
independent.
SAMPLES=val
Specifies the number of Monte Carlo samples to use for the analysis.
The default, or if SAMPLES is not specified is 1, the single-sample Monte
Carlo method. For the multi-sample Monte Carlo method, SAMPLES
must be specified as greater than 1.
SEED=val
(Optional) Specifies the beginning simulation sample. Default=2, if value
for SEED is not specified. Setting SEED=1 causes a noiseless
simulation to be performed.
TIME
(Optional) Used to specify additional time points (breakpoints) where
time-domain noise should be evaluated in addition to those time points
that will be evaluated as part of the normal time-stepping algorithm.
Use this parameter to force noise evaluation at important time points of
interest (such as rising/falling edges).
■
TIME=all: (default) causes time-domain noise ONOISE values to be
computed and available for output at all time points selected by
the .TRAN command time-step algorithm.
■
TIME=val: Specifies a single additional time point at which time
domain noise is measured. The value can be numeric or a parameter.
A .TRAN analysis at this time point will be forced.
Note that time-domain noise calculations require an
accompanying .TRAN analysis at each time point. The TIME parameter
may therefore add transient analysis time-points (breakpoints) as
needed while values given outside the range of the .TRAN command
constraints are ignored
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Keyword
Description
AUTOCORRELATION (Optional) Used to enable the autocorrelation function calculation at the
specified output.
■
■
AUTOCORRELATION=0 (OFF) - (default) Autocorrelation function is
not calculated.
AUTOCORRELATION=1 (ON) - Autocorrelation function is calculated
at the specified output.
FMIN
(Optional) Base frequency used for modeling frequency dependent noise
sources. Sets low-frequency flicker noise limit for contributing noise
sources. (Default: 1/TSTOP) See Note below.
FMAX
(Optional) Maximum frequency used for modeling frequency dependent
noise sources. Sets maximum noise source waveform bandwidth and
ensures Nyquist sampling. Default: 1/TSTEP; See Note below.
SCALE
Scale factor that can be applied to uniformly amplify the intensity of all
device noise sources to exaggerate their contributions. Default: 1.0
Note:
FMAX has a dramatic effect on TRANNOISE, since it controls
the amount of energy each noise source is allowed to emit.
Therefore, huge values of FMAX (like 100G) can result in huge
instantaneous noise levels. FMIN sets the low frequency limit for
flicker noise, and therefore controls the energy in flicker noise
sources. You can expect some significant differences with FMAX
and FMIN changes: Noise power will increase linearly with
FMAX; flicker noise power can scale as 1/FMIN.
Monte Carlo Output Data
The .TRANNOISE analysis outputs raw data to the *.tr0 and *.printtr0 files
consistent with a Monte Carlo transient analysis. Data in these output files is
organized according to the sample number which is indicated as the Monte
Carlo index.
The first sample (index=1) is used to create a noise-free simulation, i.e., all
noise sources are disabled for this simulation. Beginning with index=2, all
subsequent simulations use unique random number seeding to create unique
simulation results due to noise.
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SDE Output Data
The .TRANNOISE SDE analysis outputs raw data to the *.tr0 and *.printtr0 files
consistent with transient analysis. The .PRINT/.PROBE output syntax
supports the following measurements:
.print trannoise ONOISE ONOISE(M) VRMS(n1[,n2])
.probe trannoise ONOISE ONOISE(M) VRMS(n1[,n2])
where:
■
The ONOISE and ONOISE(M) outputs are the same. They represent noise
voltage or current at the node or branch specified by the output keyword.
The ONOISE represents the RMS noise voltage component (square root of
the variance), units in Volts, of the noise at the specified output present in
addition to the noise-less transient voltage.
■
VRMS: The output of RMS noise voltages at other nodes (i.e., the output for
general nodal noise voltage values).
Note that the actual instantaneous output voltage is the sum of the signal plus
noise components:
Equation 60
s+n
s
n
v out ( t ) = v out ( t ) + v out ( t )
n
Where the noise component v out ( t ) has an assumed Gaussian distribution (in
x ) as:
2
1 -----------e
σ 2π
–x------2
2σ
s
And the output signal v out ( t ) is that resulting from the (deterministic) .TRAN
analysis. The time-varying RMS noise voltage waveforms (i.e., for onoise) are
n
related to the variance at the specified outputs as given by v RMS ( t ) =
2
n
2
σn ( t )
n
where: σn ( t ) = v out ( t ) ⋅ v out ( t ) .
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Jitter Measurements from .TRANNOISE Analysis Results
Monte Carlo Examples
The following example generates 30 Monte Carlo noise simulations beginning
with a noiseless (index=1) simulation.
.TRANNOISE v(out) SAMPLES=30
The following example generates 20 monte carlo noise simulations starting with
the seed value (i.e., index) of 31 for the first simulation.
.TRANNOISE v(out) SAMPLES=20 SEED=31
The following example generates a single noise simulation, with seed value of
50, with all noise sources amplified by a factor of 10.
.TRANNOISE v(out) SEED=50 SCALE=10.0
SDE Examples
Example 1. SDE method with maximum frequency of 5GHz.
.TRANNOISE v(7) METHOD=SDE FMAX=5g
Example 2. Activates SDE noise analysis, and dumps the ONOISE output to the
*.tr0 file:
.TRANNOISE v(out) METHOD SDE
.PROBE TRANNOISE ONOISE
Example 3. Activates SDE noise analysis, placing a lower bound on flicker
noise to be 10kHz, and an upper bound on all noise power at 100MHz:
.TRANNOISE v(out) METHOD=SDE FMIN=10k FMAX=100MEG
Jitter Measurements from .TRANNOISE Analysis
Results
While transient noise analysis shows the effect of noise on the signal
magnitude, it is also useful to see how the noise affects the timing of the signal.
From the transient noise analysis results, jitter can be measured. The two jitter
measurements are time interval error or TIE and autocorrelation function. TIE
measures the time-shift behavior relative to a reference signal and is best
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Jitter Measurements from .TRANNOISE Analysis Results
measured using WaveView. The autocorrelation function tracks the relative
time-shift behavior of the signal.
Output Data Files
The output data from the autocorrelation function calculations is output to the
ASCII formatted *.trnz# file.
Measure TIE Jitter and Jitter Spectrum Example
The following clock buffer example circuit uses a single run Monte Carlo
transient noise analysis. Post-processing is performed using WaveView.
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Analysis Setup Details
* Transient Noise Analysis Example
.option post probe
.option runlvl=5
.paramfreq=2000MEG period=‘1.0/freq’
* Reference Clock
Vsrcref gndDC 0 PULSE (0.0 ‘vdd’
+‘0.975*period’ ‘0.05*period’ ‘0.05*period’
+ ‘0.45*period’ ‘period’)
* Clock Buffer Circuit
:
* Analysis Setup
.tran‘0.05*period’ ‘520*period’
.trannoisev(outb26) SWEEP MONTE=1 FIRSTRUN=2
+ FMAX=50G SCALE=10
.probe tranv(ref) v(outa) v(outb14) v(outb26)
.end
Figure 20
Single-run Monte Carlo Transient Noise gives noisy clock/data waveforms
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250
Figure 21
WaveView: Jitter vs. Time measurement to get Timing Interval Error (TIE)
Jitter vs. Time. Measurement based on the reference signal
Figure 22
FFT of the TIE Jitter samples show the Jitter Spectrum
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Correlating Noise Results: .TRANNOISE (Monte Carlo) and .NOISE
Correlating Noise Results: .TRANNOISE (Monte Carlo)
and .NOISE
Comparing noise results between .TRANNOISE and .NOISE simulations
requires some careful setups:
1. Pay attention to the bandwidth (i.e., frequency sweep) that you are using for
.noise. When you run .trannoise, it will always be bandwidth-limited
based on the time-stepping (tsteps) and time interval (tstop) of the
simulation. You want the same bandwidth to be reflected in the .noise, as
well. (The reason why will be clear below.)
2. If possible, test your circuit for natural bandwidth limitations, i.e., the onoise
output rolls off substantially beyond some frequency. This is true of postlayout circuits that have some capacitance at every node. If your circuit has
natural BW limits, then item #1 above isn't so critical.
3. Run your .noise simulation, and monitor the Total Output Noise Voltage in
units of Volts. This is the integrated ONOISE over the bandwidth of interest.
ONOISE values are in Volts-per-unit-sqrt(Hertz). To compare with the time
domain, you need to know the Hertz. The (integrated) total output noise
voltage is dumped to the .lis file.
4. Set up your .trannoise simulation such that the noise will not alter the
large-signal behavior of the circuit. .NOISE is a small-signal simulation. Try
to keep .trannoise signals small (e.g., no big PULSE sources) so the
comparisons will be valid. Note that with .trannoise, you don't need an
input signal, as the noise will be the signal.
5. Use the.trannoise command; set FMAX to match the integration
bandwidth (freq range) used for your .NOISE analysis. To see low
frequency range (flicker effects), your .tran command may need a big
TSTOP value. Do not set the FMIN parameter, since this sets the noise
generation. You still need a big TSTOP to observe this generated noise.
6. To compare with a single-run Monte Carlo simulation, create a .measure
command to measure RMS voltage for the same node(s) you used for
.noise output. If you can't avoid a nonlinear transient startup for your
circuit, you may need a FROM and TO for this .measure to look past it. Your
.measure results will match your Total Output Noise Voltage if the only
signal at this node is due to noise.
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Error Handling, Error Recovery, Status Reporting
7. To compare with a multi-run Monte Carlo simulation, .measure the voltage
at a particular time point of interest. When you run the simulation, the Monte
Carlo report gives you results you can compare with .noise. You may need
many samples to get stable statistical results for a single time point.
Error Handling, Error Recovery, Status Reporting
The following error checks are made with transient noise analysis:
■
Verify that the specified output node exists.
■
Verify non-negative integer values for “list” entries.
Note:
Invalid values for FMIN and FMAX will be ignored and default
values will be used.
The SDE solving can be substantially slower than transient analysis. Status
reporting includes noise analysis progress.
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References
References
[1] A. Demir, E.W.Y. Liu, A.L. Sangiovanni-Vincentelli, “Time-domain nonMonte Carlo noise simulation for nonlinear dynamic circuits with arbitrary
excitations,” IEEE Trans. CAD, vol. 15, no. 5. May 1996.
[2] P. Bolcato and R. Poujois, “A new approach for noise simulation in transient
analysis”, Proc. IEEE Int. Symp. Circuits Syst., pp. 887-890, May 1992.
[3] J. A. McNeill, “Jitter in ring oscillators,” Ph.D. dissertation, Boston University,
1994.
[4] M. Okumura and H. Tanimoto, “A time-domain method for numerical noise
analysis of oscillators”, Proc. IEEE Asia Pacific Design Automation
Conference, 1997.
[5] A. van der Ziel, Noise in Solid State Devices and Circuits, John Wiley &
Sons, 1986.
[6] A. Hajimiri, S. Limotyrakis, and T.H. Lee, “Jitter and phase noise in ring
oscillators,” IEEE J. Solid-State Circuits, vol. 34, no. 6, pp. 790-804, June
1999.
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References
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10
10
S-parameter Analyses
Describes how to do frequency translation and large-signal
S-parameter extraction, as well as noise parameter calculation.
These topics are covered in the following sections:
■
Frequency Translation S-Parameter (HBLIN) Extraction on page 256
■
Large-Signal S-parameter (HBLSP) Analysis on page 263
This chapter discusses various techniques supported in HSPICE RF for
extracting circuit scattering parameters. Since RF circuits can operate under
large-signal and small-signal conditions, there are several types of scattering
parameters that are useful to measure.
Linear small-signal scattering parameters represent the RF frequency-domain
transfer characteristics for a circuit that is operating at its DC bias condition, but
the stimulus and response signals are sufficiently small that they do not
influence the operating point. This type of analysis is performed using the .LIN
analysis, which is supported in both HSPICE and HSPICE RF. For information
on doing small-signal S-parameter analysis (.LIN), please see (Linear Network
Parameter Analysis) in the HSPICE User Guide: Simulation and Analysis.
In the case of RF mixers and receiver front-ends, some of the input and output
frequencies of interest involve a frequency translation. This translation is
intentional and caused by nonlinear mixing in the circuit due to devices being
driven by large-signal periodic waveforms. This type of scattering parameter
analysis therefore must begin by solving the large-signal periodic response,
and then finding the small-signal behavior about this large-signal operating
point. This capability is provided by the .HBLIN analysis, which has setup and
analysis control options similar to .LIN, but is capable of extracting
S-parameters about a large-signal periodic steady-state operating point.
In the case of circuits such as power amplifiers, the extraction of scattering
parameters is also important, but the circuit stimulus and response signals may
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Frequency Translation S-Parameter (HBLIN) Extraction
themselves be large-signal periodic waveforms. And, it can be important to
analyze how these S-parameter vary as a function of input power levels. This
capability is provided by the .HBLSP Large-Signal S-parameter analysis, which
uses large-signal stimulus signals for the S-parameter extractions.
Frequency Translation S-Parameter (HBLIN) Extraction
Frequency translation scattering parameter (S-parameter) extraction is used to
describe N-port circuits that exhibit frequency translation effects, such as
mixers. The analysis is similar to the existing LIN analysis, except that the
circuit is first linearized about a periodically varying operating point instead of a
simple DC operating point. After the linearization, the S-parameters between
circuit ports that convert signals from one frequency band to another are
calculated.
You use the .HBLIN statement to extract frequency translation S-parameters
and noise figures.
Frequency translation S-parameter describes the capability of a periodically
linear time varying systems to shift signals in frequency. The S-parameters for
a frequency translation system are similar to the S-parameters of a linear-timevarying system, it is defined as:
b = S⋅ a
Equation 61
b i,m ( ω)
----------------S i,j;m,n ( ω) =
a j,n ( ω)
a k ≠ j, p ≠ n ( ω) = 0
The incident waves, a i ,n ( ω) , and reflected waves, b i ,n ( ω) , are defined by using
these equations:
Equation 62
256
V i ( ω + nω0 ) + Z 0i I i ( ω + nω0 )
---------------------------------------------------------------------a i ,n ( ω) =
2 Z 0i
V i ( ω + nω0 ) – Z 0i I i ( ω + nω0 )
b i ,n ( ω) = ---------------------------------------------------------------------2 Z 0i
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Where,
■
ω0 is the fundamental frequency (tone).
■
n is a signed integer.
■
i is the port number.
■
a i ,n ( ω) is the input wave at the frequency ω + nω0 on the ith port.
■
b i ,n ( ω) is the reflected wave at the frequency ω + nω0 on the ith port.
■
V i ( ω + nω0 ) is the Fourier coefficient at the frequency ω + nω0 of the voltage
at port i.
■
I i ( ω + ωn 0 ) is the Fourier coefficient at the frequency ω + nω0 of the current
at port i.
■
Z 0i is the reference impedance at port i.
■
V and I definitions are Fourier coefficients rather than phasors.
For a multi-tone analysis, it can be expressed as:
b = S⋅ a
b i ,m ,m ...m ( ω)
1
2
N
( ω) = ------------------------------------Si
,j;m 1 ...m N ,n 1 ,n 2 ...n N
a j ,n ,n ...n ( ω)
Equation 63
1
2
N
a k ,p ,p ...p k ≠ j ,∇ p ≠ n ( ω) = 0
1 2
N
q
q
Equation 64
Where,
■
ωj is the ith tone.
The frequency translate S-parameters are calculated by applying different
n j ( j = 1 ∼N ) to different ports.
Limitations
The HBLIN analysis has these known limitations:
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N
N
∑
∑
⎛
⎞
⎛
⎞
⎜
⎟
⎜
Vi ω +
n j ωj + Z 0i I i ω +
n j ωj⎟
⎜
⎟
⎜
⎟
⎝
⎠
⎝
⎠
j=1
j=1
a i ,n ,n ...n ( ω) = ---------------------------------------------------------------------------------------------1 2
N
2 Z oi
N
N
∑
∑
⎛
⎞
⎛
⎞
⎜
⎟
⎜
Vi ω +
n j ωj – Z 0i I i ω +
n j ωj⎟
⎜
⎟
⎜
⎟
⎝
⎠
⎝
⎠
j=1
j=1
b i ,n ,n ...n ( ω) = ------------------------------------------------------------------------------------------1 2
N
2 Z oi
■
Noise parameters are not calculated for mixed-mode operation.
■
Only the S-parameters corresponding to the set of frequencies specified at
each port are extracted.
■
Multiple small-signal tones are not supported.
■
The port (P) element impedance cannot be specified as complex.
HB Analysis
An HB analysis is required prior to an HBLIN analysis. To extract the frequency
translation S-parameters, a sweep of the small-signal tone is necessary. You
can identify the small-signal tone sweep in the .HBLIN command or in the .HB
command together with a SS_TONE specification.
For additional information regarding HB analysis, see Harmonic Balance
Analysis on page 108.
Port Element
You must use a port (P) element as the termination at each port of the system.
To indicate the frequency band that the S-parameters are extracted from, it is
necessary to specify a harmonic index for each P-element.
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Port Element Syntax
Without SS_TONE
Pxxx p n n_ref PORT=portnumber
+ [HBLIN = [H1, H2, ... HN, +/-1]] ...
With SS_TONE
Pxxx p n n_ref [PORT=portnumber]
+ [HBLIN = [H1, H2, ... +/-1 ... HN]] ...
Parameter
Description
n_ref
Reference node used when a mixed-mode port is specified.
PORT
The port number. Numbered sequentially beginning with 1 with no
shared port numbers.
HBLIN
Integer vector that specifies the harmonic index corresponding to the
tones defined in the .HB command. The +/-1 term corresponds to the
small-signal tone specified by SS_TONE in the .HB command. If there
is no SS_TONE in the .HB command, the +/-1 term must be at the last
entry of HBLIN vector.
HBLIN Analysis
You use the .HBLIN statement to extract frequency translation S-parameters
and noise figures.
Input Syntax
Without SS_TONE
.HBLIN frequency_sweep
+ [NOISECALC = [1|0|yes|no]] [FILENAME=file_name]
+ [DATAFORMAT = [ri|ma|db]]
+ [MIXEDMODE2PORT = [dd|cc|cd|dc|sd|sc|cs|ds]]
With SS_TONE
.HBLIN [NOISECALC = [1|0|yes|no]] [FILENAME=file_name]
+ [DATAFORMAT = [ri|ma|db]]
+ [MIXEDMODE2PORT = [dd|cc|cd|dc|sd|sc|cs|ds]]
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Parameter
Description
frequency_sweep
Frequency sweep range for the input signal (also referred to as
the input frequency band (IFB) or fin). You can specify LIN,
DEC, OCT, POI, or SWEEPBLOCK. Specify the nsteps, start,
and stop frequencies using the following syntax for each type of
sweep:
■
■
■
■
■
■
NOISECALC
Enables calculating the noise figure. The default is no (0).
FILENAME
Specifies the output file name for the extracted S-parameters or
the object name after the -o command-line option. The default
is the netlist file name.
DATAFORMAT
Specifies the format of the output data file.
■
■
■
260
LIN nsteps start stop
DEC nsteps start stop
OCT nsteps start stop
POI nsteps freq_values
SWEEPBLOCK nsteps freq1 freq2 ... freqn
DATA=dataname
dataformat=RI, real-imaginary.
dataformat=MA, magnitude-phase. This is the default format
for Touchstone files.
dataformat=DB, DB(magnitude)-phase.
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Parameter
Description
MIXEDMODE2PORT Describes the mixed-mode data map of output mixed mode Sparameter matrix. The availability and default value for this
keyword depends on the first two port (P element) configuration
as follows:
■
■
■
■
case 1: p1=p2=single-ended (standard-mode P element)
available: ss
default: ss
case 2: p1=p2=balanced (mixed-mode P element)
available: dd, cd, dc, cc
default: dd
case 3: p1=balanced p2=single-ended
available: ds, cs
default: ds
case 4: p1=single p2=balanced
available: sd, sc
default: sd
Example 1
Single-tone analysis with frequency translation. In this example, the 2-port Sparameters from RF (1G-del_f) to IF (del_f) are extracted. The LO signal is
specified by normal voltage source Vlo. The frequency on port 1 is in the RF
band, 1G-del_f, and the frequency on port 2 is in the IF band, del_f. The IF
band is swept from 0- to 100-MHz. The results are output to file ex1.s2p.
p1 RFin gnd port=1 HBLIN=(1,-1)
p2 IFout gnd port=2 HBLIN=(0,1)
Vlo LOin gnd DC 0 HB 2.5 0 1 1
.HB tones=1G harms=5
.HBLIN lin 5 0 100meg noisecalc=no filename=ex1
+ dataformat=ma
Example 2
Another single-tone analysis with frequency translation example. In this
example, the 3-port S-parameters are extracted. Port 3 provides the periodic
large signal. The frequency on port 1 is del_f, the frequency on port 2 is
1G*2-del_f, and the frequency on port 3 is 1G*1+del_f. The small-signal
frequency is swept from 0 to 100MHz. HBNOISE calculation is required. The
results are output to file ex2.s3p.
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p1 1 0 port=1 HBLIN=(0, 1)
p2 2 0 port=2 HBLIN=(2, -1)
p3 3 0 port=3 hb 0.5 0 1 1 HBLIN=(1, 1)
.HB tones=1G harms=5
.HBLIN lin 5 0 100meg noisecalc=yes filename=ex2
Output Syntax
This section describes the syntax for the HBLIN .PRINT and .PROBE
statements.
.PRINT and .PROBE Statements
.PRINT
.PROBE
.PRINT
.PROBE
.PRINT
.PROBE
HBLIN Smn | Smn(TYPE) | S(m,n) | S(m,n)(TYPE)
HBLIN Smn | Smn(TYPE) | S(m, n) | S(m, n)(TYPE)
HBLIN SXYmn | SXYmn(TYPE) | SXY(m,n) | SXY(m,n)(TYPE)
HBLIN SXYmn | SXYmn(TYPE) | SXY(m, n) | SXY(m, n)(TYPE)
HBLIN NF SSNF DSNF
HBLIN NF SSNF SSNF
Parameter
Description
Smn | Smn(TYPE) |
Complex 2-port parameters. Where:
S(m,n) | S(m,n)(TYPE)
■
m = 1 or 2
SXYmn | SXYmn(TYPE) |
■
n = 1 or 2
SXY(m,n) | SXY(m,n)(TYPE) ■ X and Y are used for mixed-mode S-parameter
output. The values for X and Y can be D
(differential), C (common), or S (single-end).
■
TYPE = R, I, M, P, PD, D, DB, or DBM
R = real
I = imaginary
M = magnitude
P = PD = phase in degrees
D = DB = decibels
DBM = decibels per 1.0e-3
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Parameter
Description
NF
SSNF
NF and SSNF both output a single-side band noise
figure as a function of the IFB points:
NF = SSNF = 10 Log(SSF)
Single side-band noise factor, SSF = {(Total Noise at
output, at OFB, originating from all frequencies) - (Load
Noise originating from OFB)} / (Input Source Noise
originating from IFB).
DSNF
DSNF outputs a double side-band noise figure as a
function of the IFB points.
DSNF = 10 Log(DSF)
Double side-band noise factor, DSF = {(Total Noise at
output, at the OFB, originating from all frequencies) (Load Noise originating from the OFB)} / (Input Source
Noise originating from the IFB and from the image of
IFB).
Output Data Files
An HBLIN analysis produces these output data files:
■
The S-parameters from the .PRINT statement are written to a .printhl# file.
■
The extracted S-parameters from the .PROBE statement are written to
a .hl# file.
Large-Signal S-parameter (HBLSP) Analysis
An HBLSP analysis provides three kinds of analyses for periodically-driven
nonlinear circuits, such as those that employ power amplifiers and filters:
■
Two-port power-dependant (large-signal) S-parameter extraction
■
Two-port small-signal S-parameter extraction
■
Two-port small-signal noise parameter calculation
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Unlike small-signal S-parameters, which are based on linear analysis, powerdependent S-parameters are based on harmonic balance simulation. Its
solution accounts for nonlinear effects such as compression and variation in
power levels.
The definition for power-dependent S-parameters is similar to that for smallsignal parameters. Power-dependent S-parameters are defined as the ratio of
reflected and incident waves by using this equation:
b=S*a ;
S[i, j]=b[i,n]/a[j,n]
when a[k,n](k!=j)=0
The incident waves, a[i, n], and reflected waves, b[i, n], are defined by using
these equations:
a[i, n] = (V[i](n*W0) + Zo[i] * I[i](n*W0)) / (2 * sqrt(Zo[i]))
b[i, n] = (V[i](n*W0) - Zo[i] * I[i](n*W0)) / (2 * sqrt(Zo[i]))
Where:
■
W0 is the fundamental frequency (tone).
■
n is a signed integer.
■
i is the port number.
■
a[i, n] is the input wave at the frequency n*W0 on the ith port.
■
b[i, n] is the reflected wave at the frequency n*W0 on the ith port.
■
V[i](n*W0) is the Fourier coefficient at the frequency n*W0 of the voltage at
port i.
■
I[i](n*W0) is the Fourier coefficient at the frequency n*W0 of the current at
port i.
■
Zo[i] is the reference impedance at port i.
An HBLSP analysis only extracts the S-parameters on the first harmonic (that
is, n=1).
Limitations
The HBLSP analysis has these known limitations:
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■
Power-dependent S-parameter extraction is a 2-port analysis only. Multiport
power-dependent S-parameters are not currently supported.
■
The intermodulation data block (IMTDATA) in the .p2d# file is not supported.
■
The internal impedance of the P (port) Element can only be a real value.
Complex impedance values are not supported.
Input Syntax
.HBLSP NHARMS=nh [POWERUNIT=[dbm|watt]]
+ [SSPCALC=[1|0|YES|NO]] [NOISECALC=[1|0|YES|NO]]
+ [FILENAME=file_name] [DATAFORMAT=[ri|ma|db]]
+ FREQSWEEP freq_sweep POWERSWEEP power_sweep
Parameter
Description
NHARMS
Number of harmonics in the HB analysis triggered by the .HBLSP
statement.
POWERUNIT
Power unit. Default is watt.
SSPCALC
Extract small-signal S-parameters. Default is 0 (NO).
NOISECALC
Perform small-signal 2-port noise analysis. Default is 0 (NO).
FILENAME
Output data .p2d# filename. Default is the netlist name or the object
name after the -o command-line option.
DATAFORMAT
Format of the output data file. Default is ma (magnitude, angle).
FREQSWEEP
Frequency sweep specification. A sweep of type LIN, DEC, OCT,
POI, or SWEEPBLOCK. Specify the nsteps, start, and stop times
using the following syntax for each type of sweep:
■
■
■
■
■
LIN nsteps start stop
DEC nsteps start stop
OCT nsteps start stop
POI nsteps freq_values
SWEEPBLOCK=blockname
This keyword must appear before the POWERSWEEP keyword.
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Parameter
Description
POWERSWEEP Power sweep specification. A sweep of type LIN, DEC, OCT,POI, or
SWEEPBLOCK. Specify the nsteps, start, and stop frequencies
using the following syntax for each type of sweep:
■
■
■
■
■
LIN nsteps start stop
DEC nsteps start stop
OCT nsteps start stop
POI nsteps power_values
SWEEPBLOCK=blockname
This keyword must follow the FREQSWEEP keyword.
Note:
The FREQSWEEP and POWERSWEEP keywords must appear at the
end of an .HBLSP statement.
Examples
Example 1 does 2-port single-tone, power-dependent S-parameter extraction,
without frequency translation:
■
Frequency sweep: The fundamental tone is swept from 0 to 1G
■
Power sweep: The power input at port 1 is swept from 6 to 10 Watts.
■
Five harmonics are required for the HB analysis. Large-signal S-parameters
are extracted on the first harmonic.
■
Five harmonics are required in the HBLSP triggered HB analysis.
■
The DC value in p1 statement is used to set DC bias, which is used to
perform small-signal analyses.
■
Small-signal S-parameters are required extracted.
■
Small-signal two-port noise analysis is required.
■
The data will be output to the ex1.p2d file.
Example 1
2-Port, Single Tone
p1 1 0 port=1 dc=1v
p2 2 0 port=2
.hblsp nharms=5 powerunit = watt
+ sspcalc=1 noisecalc=1 filename=ex1
+ freqsweep lin 5 0 1G powersweep lin 5 6 10
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Example 2 generates large scale S-parameters as a function of input for a
differential equalizer.
Example 2
4-Port Network
* hblsp example
.opt post
p1 n1 0 port=1 ac=1
p2 n2 0 port=2
*** put your DUT
R1 n1 n2 10***
.hblsp nharms=5
+ freqsweep lin 4 1k 10k
+ powersweep lin 2 5 10
.end
Output Syntax
This section describes the syntax for the HBLSP .PRINT and .PROBE
statements. These statements only support S and noise parameter outputs.
Node voltage, branch current, and all other parameters are not supported in
HBLSP .PRINT and .PROBE statements.
.PRINT and .PROBE Statements
.PRINT HBLSP Smn | Smn(TYPE) |
+ ...small signal 2-port noise
.PROBE HBLSP Smn | Smn(TYPE) |
+ ...small signal 2-port noise
S(m, n) | S(m, n)(TYPE)
params...
S(m, n) | S(m, n)(TYPE)
params...
Parameter
Description
Smn | Smn(TYPE) |
S(m,n) | S(m,n)(TYPE)
Complex 2-port parameters. Where:
■
■
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m = 1 or 2
n = 1 or 2
TYPE = R, I, M, P, PD, D, DB, or DBM
R = real
I = imaginary
M = magnitude
P = PD = phase in degrees
D = DB = decibels
DBM = decibels per 1.0e-3
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Parameter
Description
... small signal 2-port noise
parameters ...
G_AS | NF | RN | YOPT | GAMMA_OPT | NFMIN |
VN2 | ZCOR | GN | RHON | YCOR | ZOPT | IN2
For a description of these parameters, see Linear
Network Parameter Analysis in the HSPICE User
Guide: Simulation and Analysis.
Output Data Files
An HBLSP analysis produces these output data files:
■
The large-signal S-parameters from the .PRINT statement are written to
a .printls# file.
■
The small-signal S-parameters from the .PRINT statement are written to
a .printss# file.
■
The large-signal S-parameters from the .PROBE statement are written to
a .ls# file.
■
The small-signal S-parameters from the .PROBE statement are written to
a .ss# file.
■
The extracted large- and small-signal S and noise parameters are written to
a .p2d# file.
The large- and small-signal S-parameters from the .PROBE statement are
viewable in Custom WaveView.
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Envelope Analysis
11
Describes how to use envelope simulation.
These topics are covered in the following sections:
■
Envelope Simulation
■
Envelope Analysis Commands
■
Nonautonomous Form
■
Oscillator Analysis Form
■
Fast Fourier Transform Form
■
Output Syntax
Envelope Simulation
Envelope simulation combines features of time- and frequency-domain
analysis. Harmonic Balance (HB) solves for a static set of phasors for all the
circuit state variables, as shown in this equation:
N
Equation 65
v ( t ) = a0 +
∑ [ ai cos ωi t + bi sin ωi t ]
i=1
In contrast, envelope analysis finds a dynamic, time-dependent set of phasors,
as this equation shows:
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Equation 66
v ( t ) = a 0 ( ˆt ) +
N
∑ [ ai (ˆt ) cos ωi t + bi (ˆt ) sin ωi t ]
i=1
Thus, in envelope simulation, each signal is described by the evolving
spectrum. Envelope analysis is generally used on circuits excited by signals
with significantly different timescales. An HB simulation is performed at each
point in time of the slower-moving ( ˆt ) timescale. In this way, for example, a 2tone HB simulation can be converted into a series of related 1-tone simulations
where the transient analysis proceeds on the ( ˆt ) timescale, and 1-tone HB
simulations are performed with the higher frequency tone as the fundamental
frequency.
In HSPICE RF, any voltage or current source identified as a HB source either in
a V or I element statement, or by an .OPTION TRANFORHB command, is used
for HB simulations at each point in ˆt time. All other sources are associated with
the transient timescale. Also, the input waveforms can be represented in the
frequency domain as RF carriers modulated by an envelope by identifying a
VMRF signal source in a V or I element statement. The amplitude and phase
values of the sampled envelope are used as the input signal for HB analysis.
Some typical applications for envelope simulation are amplifier spectral
regrowth, adjacent channel power ration (ACPR), and oscillator startup and
shutdown analyses.
Envelope Analysis Commands
This section describes those commands specific to envelope analysis. These
commands are:
■
Standard envelope simulation (.ENV)
■
Oscillator simulation, both startup and shutdown (.ENVOSC)
■
Envelope Fast Fourier Transform (.ENVFFT)
Nonautonomous Form
.ENV TONES=f1 [f2...fn] NHARMS=h1 [h2...hn]
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+ ENV_STEP=tstep ENV_STOP=tstop
Parameter
Description
TONES
Carrier frequencies, in hertz.
NHARMS
Number of harmonics.
ENV_STEP
Envelope step size, in seconds.
ENV_STOP
Envelope stop time, in seconds.
Description
You use the .ENV command to do standard envelope simulation. The
simulation proceeds just as it does in standard transient simulation, starting at
time=0 and continuing until time=env_stop. An HB analysis is performed at
each step in time. You can use Backward-Euler (BE), trapezoidal (TRAP), or
level-2 Gear (GEAR) integration.
Recommended option settings are:
■
For BE integration, set .OPTION SIM_ORDER=1.
■
For TRAP, set .OPTION SIM_ORDER=2 (default) METHOD=TRAP (default).
■
For GEAR, set .OPTION SIM_ORDER=2 (default) METHOD=GEAR.
Example
.env tones=1e9 nharms=6 env_step=10n env_stop=1u
Oscillator Analysis Form
.ENVOSC TONE=f1 NHARMS=h1 ENV_STEP=tstep ENV_STOP=tstop
+ PROBENODE=n1,n2,vosc <FSPTS=num, min, max>
Parameter
Description
TONE
Carrier frequencies, in hertz.
NHARMS
Number of harmonics.
ENV_STEP
Envelope step size, in seconds.
ENV_STOP
Envelope stop time, in seconds.
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Parameter
Description
PROBENODE
Defines the nodes used for oscillator conditions and the initial
probe voltage value.
FSPTS
Specifies the frequency search points used in the initial smallsignal frequency search. Usage depends on oscillator type.
Description
You use the .ENVOSC command to do envelope simulation for oscillator startup
or shutdown.
Oscillator startup or shutdown analysis with this command must be helped
along by converting a bias source from a DC description to a PWL description
that either:
■
Starts at a low value that supports oscillation and ramps up to a final value
(startup simulation)
■
Starts at the DC value and ramps down to zero (shutdown simulation).
In addition to solving for the state variables at each envelope time point, the
.ENVOSC command also solves for the frequency. This command is intended to
be applied to high-Q oscillators that take a long time to reach steady-state. For
these circuits, standard transient analysis is too costly. Low-Q oscillators, such
as typical ring oscillators, are more efficiently simulated with standard transient
analysis.
Example
.envosc tone=250Meg nharms=10 env_step=20n env_stop=10u
+ probenode=v5,0,1.25
Fast Fourier Transform Form
.ENVFFT output_var [NP=val] [FORMAT=keyword]
+[<WINDOW=keyword] [ALFA=val]
272
Parameter
Description
output_var
Any valid output variable.
NP
The number of points to use in the FFT analysis. NP must be a
power of 2. If not a power of 2, then it is automatically adjusted to
the closest higher number that is a power of 2. The default is 1024.
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Parameter
Description
FORMAT
Specifies the output format:
NORM= normalized magnitude
UNORM=unnormalized magnitude (default)
WINDOW
Specifies the window type to use:
RECT=simple rectangular truncation window (default)
BART=Bartlett (triangular) window
HANN=Hanning window
HAMM=Hamming window
BLACK=Blackman window
HARRIS=Blackman-Harris window
GAUSS=Gaussian window
KAISER=Kaiser-Bessel window
ALFA
Controls the highest side-lobe level and bandwidth for GAUSS and
KAISER windows. The default is 3.0.
Description
You use the .ENVFFT command to perform Fast fourier Transform (FFT) on
envelope output. This command is similar to the .FFT command. The only
difference is that transformation is performed on real data with the .FFT
command, and with the .ENVFFT command, the data being transformed is
complex. You usually want to do this for a specific harmonic of a voltage,
current, or power signal.
Example
.envfft v(out)[1]
Output Syntax
The results from envelope simulation can be made available through the
.PRINT, .PROBE, and .MEASURE commands. This section describes the basic
syntax you can use for this purpose.
.PRINT or .PROBE
You can print or probe envelope simulation results by using the following
commands:
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.PRINT ENV ov1 <ov2... >
.PROBE ENV ov1 <ov2... >
Where ov1... are the output variables to print or probe.
.MEASURE
In HSPICE RF, the independent variable for envelope simulation is the first
tone. Otherwise and except for the analysis type, the .MEASURE statement
syntax is the same as the syntax for HB; for example,
.MEASURE ENV result ...
Envelope Output Data File Format
The results of envelope simulations are written to *.ev# data files by the
.PROBE statement. The format of an *.ev# data file is equivalent to an *.hb#
data file with the addition of one fundamental parameter sweep that represents
the slowly-varying time-envelope variation ˆt of the Fourier coefficients and
frequencies. You can recognize this swept parameter” in the *.ev# file by the
keyword env_time.
Each row in the tabulated data of an *.ev# file includes values for identifying
frequency information, the complex data for the output variables, and
information on the envelope time sweep. For example, the header for a data file
dump for output variables v(in) and v(out) that follow a 2-tone envelope
analysis, have entries for:
hertz
v(in)
v(out)
n0
f0
n1
f1
sweep
env_time
$&%#
Which result in data blocks with floating point values following:
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env_time[0]
f[0] a[0]{v(in)} b[0] {v(in)} a[0] {v(out)} b[0] {v(out)} n0
f0 n1 f1
f[1] a[1]{v(in)} b[1] {v(in)} a[1] {v(out)} b[1] {v(out)} n0
f0 n1 f1
...
f[N] a[N]{v(in)} b[N] {v(in)} a[N] {v(out)} b[N] {v(out)} n0
f0 n1 f1
env_time[1]
f[0] a[0]{v(in)} b[0] {v(in)} a[0] {v(out)} b[0] {v(out)} n0
f0 n1 f1
f[1] a[1]{v(in)} b[1] {v(in)} a[1] {v(out)} b[1] {v(out)} n0
f0 n1 f1
...
f[N] a[N]{v(in)} b[N] {v(in)} a[N] {v(out)} b[N] {v(out)} n0
f0 n1 f1
...
env_time[M-1]
f[0] a[0]{v(in)} b[0] {v(in)} a[0] {v(out)} b[0] {v(out)} n0
f0 n1 f1
f[1] a[1]{v(in)} b[1] {v(in)} a[1] {v(out)} b[1] {v(out)} n0
f0 n1 f1
...
f[N] a[N]{v(in)} b[N] {v(in)} a[N] {v(out)} b[N] {v(out)} n0
f0 n1 f1
Where there are M data blocks corresponding to M envelope time points, with
each block containing N+1 rows for the frequency data. The units for the
env_time sweep are seconds.
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12
Post-Layout Analysis
Describes the post-layout analysis flow, including post-layout back-annotation,
DSPF and SPEF files, linear acceleration, check statements, and power
analysis.
These topics are covered in the following sections:
■
Post-Layout Back-Annotation
■
Linear Acceleration Control Options Summary
Post-Layout Back-Annotation
A traditional, straightforward, “brute-force” flow runs an RC extraction tool that
produces a detailed standard parasitic format (DSPF) file. DSPF is the
standard format for transferring RC parasitic information. This traditional flow
then feeds this DSPF file into the circuit simulation tool for post-layout
simulation.
A key problem is that the DSPF file is flat. Accurately simulating a complete
design, such as an SRAM or an on-chip cache, is a waste of workstation
memory, disc space usage, and simulation runtime. Because this DSPF file is
flat, control and analysis are limited.
■
How do you set different options for different blocks for better trade-off
between speed and accuracy?
■
How do you perform a power analysis on a flat netlist to check the power
consumption?
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■
This traditional flow flattens all nodes after extraction so it is more difficult to
compare the delay before and after extraction.
■
This traditional flow can also stress the limits of an extraction tool so
reliability also becomes an issue.
HSPICE RF provides a flow that solves all of these problems.
■
Star-RCXT generates a hierarchical Layout Versus Schematic (LVS) ideal
netlist, and flat information about RC parasitics in a DSPF or (standard
parasitic exchange format (SPEF) file.
■
HSPICE RF uses the hybrid flat-hierarchical approach to back-annotate the
RC parasitics, from the DSPF or SPEF file, into the hierarchical LVS ideal
netlist.
Using the hierarchical LVS ideal netlist cuts simulation runtime and CPU
memory usage. Because HSPICE RF uses the hierarchical LVS ideal netlist as
the top-level netlist, you can fully control the netlist. For example:
■
You can set different modes to different blocks for better accuracy and speed
trade-off.
■
You can run power analysis, based on the hierarchical LVS ideal netlist, to
determine the power consumption of each block. If you use the hierarchical
LVS ideal netlist, you can reuse all post-processing statements from the prelayout simulation for the post-layout simulation. This saves time, and the
capacity of the verification tool is not stressed so reliability is higher.
HSPICE RF supports only the XREF:COMPLETE flow and the XREF:NO flow
from Star-RCXT. Refer to the Star-RCXT User Guide for more information
about the XREF flow.
To generate a hierarchical LVS ideal netlist with Star-RCXT, include the
following options in the Star-RCXT command file.
*** for XREF:NO flow ***
NETLIST_IDEAL_SPICE_FILE: ideal_spice_netlist.sp
NETLIST_IDEAL_SPICE_TYPE: layout
NETLIST_IDEAL_SPICE_HIER:YES
*** for XREF:COMPLETE flow ***
NETLIST_IDEAL_SPICE_FILE: ideal_spice_netlist.sp
NETLIST_IDEAL_SPICE_TYPE: schematic
NETLIST_IDEAL_SPICE_HIER:YES
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Note:
Before version 2002.2, Star-RCXT used
NETLIST_IDEAL_SPICE_SKIP_CELLS to generate the
hierarchical ideal SPICE netlist. HSPICE RF can still simulate
post-layout designs using the brute-force flow, but the post-layout
flow is preferable in HSPICE RF.
HSPICE RF supports these post-layout flows to address your post-layout
simulation needs.
■
Standard Post-Layout Flow
■
Selective Post-Layout Flow
■
Additional Post-Layout Options
Standard Post-Layout Flow
Use this flow mainly for analog or mixed signal design, and high-coverage
verification runs when you need to back-annotate RC parasitics into the
hierarchical LVS ideal netlist. In this flow, HSPICE RF expands all nets from the
DSPF or SPEF file. To expand only selected nets, use see Selective PostLayout Flow on page 283.
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Post-Layout Back-Annotation
Extraction Tool
Ideal Netlist
DSPF
SPEF
HSPICE RF
Back-annotation
.html
.lis
Figure 23
Standard Post-Layout Flow
Standard Post-Layout Flow Control Options
The standard post-layout flow options are SIM_DSPF and SIM_SPEF. Include
one of these options in your netlist. For example,
.OPTION SIM_DSPF=“[scope] dspf_filename”
.OPTION SIM_SPEF=“spec_filename”
In the SIM_DSPF syntax, scope can be a subcircuit definition or an instance. If
you do not specify scope, it defaults to the top-level definition. HSPICE RF
requires both a DSPF file and an ideal netlist. Only flat DSPF files are
supported; hierarchy statements, such as .SUBCKT and .x1, are ignored.
Very large circuits generate very large DSPF files; this is when using either the
SIM_DSPF or the SIM_DSPF_ACTIVE option can really improve performance.
You can specify a DSPF file in the SIM_SPEF option, or a SPEF file in the
SIM_DSPF option. The scope function is not supported in the SPEF format.
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For descriptions and usage examples, see .OPTION SIM_DSPF and .OPTION
SIM_SPEF in the HSPICE Reference Manual: Commands and Control
Options.
Example
$ models
.MODEL p pmos
.MODEL n nmos
.INCLUDE add4.dspf
.OPTION SIM_DSPF=“add4.dspf”
.VEC “dspf_adder.vec”
.TRAN 1n 5u
vdd vdd 0 3.3
.OPTION POST
.END
SIM_DSPF With SIM_LA Option
The SIM_DSPF option accelerates the simulation by more than 100%. By using
the SIM_LA option at the same time, you can further reduce the total CPU time:
$ models
.MODEL p pmos
.MODEL n nmos
.INCLUDE add4.dspf
.OPTION SIM_DSPF="add4.dspf"
.OPTION SIM_LA=PACT
.VEC "dspf_adder.vec"
.TRAN 1n 5u
vdd vdd 0 3.3
.OPTION POST
.END
To expand only active nodes, such as those that move, include the
SIM_DSPF_ACTIVE option in your netlist. For example:
.OPTION SIM_DSPF_ACTIVE=“active_net_filename”
This option is most effective when used with a large design—for example, over
5K transistors. Smaller designs lose some of the performance gain, due to
internal overhead processing.
For syntax and description of SIM_DSPF_ACTIVE option, see .OPTION
SIM_DSPF_ACTIVE in the HSPICE Reference Manual: Commands and
Control Options.
When you have included the appropriate control option, run HSPICE RF, using
the ideal netlist.
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The structure of a DSPF file is:
*|DSPF 1.0
*|DESIGN “demo”
*|Date “October 6, 1998”
...
.SUBCKT < name > < pins >
* Net Section
C1 ...
R1 ...
...
* Instance Section
...
.ENDS
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Selective Post-Layout Flow
Extraction Tool
DSPF
SPEF
Ideal Netlist
HSPICE RF
Active Nodes
Back-annotation
HSPICE RF
.html
.lis
Figure 24
Selective Post-Layout Flow
You can use the selective post-layout flow to simulate a post-layout design for a
memory or digital circuit, and for a corner-point verification run. Instead of backannotating all RC parasitics into the ideal netlist, the selective post-layout flow
automatically detects and back-annotates only active parasitics, into the
hierarchical LVS ideal netlist. For a high-latency design, the selective postlayout flow is an order of magnitude faster than the standard post-layout flow.
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Note:
The selective post-layout flow applies only to RF transient
analyses and cannot be used with other analyses such as DC,
AC, or HB.
Selective Post-Layout Flow Control Options
To invoke the selective post-layout flow, include one of the options listed in
Table 13 in your netlist.
Table 13
Selective Post-Layout Flow Options
Syntax
Description
SIM_DSPF_ACTIVE
-orSIM_SPEF_ACTIVE
HSPICE RF performs a preliminary verification run to
determine the activity of the nodes and generates two ASCII
files: active_node.rc and active_node.rcxt. These files save
all active node information in both Star-RC format and StarRCXT format.
By default, a node is considered active if the voltage varies
by more than 0.1V. To change this value, use the
SIM_DSPF_VTOL or SIM_SPEF_VTOL option.
For descriptions and usage examples, see OPTION
SIM_DSPF_ACTIVE and .OPTION SIM_SPEF_ACTIVE in
the HSPICE Reference Manual: Commands and Control
Options.
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Table 13
Selective Post-Layout Flow Options (Continued)
Syntax
Description
SIM_DSPF_VTOL
-orSIM_SPEF_VTOL
HSPICE RF performs a second simulation run by using the
active_node file, the DSPF or SPEF file, and the hierarchical
LVS ideal netlist to back-annotate only active portions of the
circuit. If a net is latent, then HSPICE RF does not expand
the net. This saves simulation runtime and memory.
■
■
value is the tolerance of the voltage change.
scopen can be a subcircuit definition (which has an @
prefix), or a subcircuit instance.
By default, HSPICE RF performs only one iteration of the
second simulation run. Use the SIM_DSPF_MAX_ITER or
SIM_SPEF_MAX_ITER option to change it.
For descriptions and usage examples, see .OPTION
SIM_DSPF_VTOL and .OPTION SIM_SPEF_VTOL in the
HSPICE Reference Manual: Commands and Control
Options.
SIM_DSPF_MAX_ITER value is the maximum number of iterations for the second
-orsimulation run.
SIM_SPEF_MAX_ITER
Some of the latent nets might turn active after the first
iteration of the second run. In this case:
■
■
Resimulate the netlist to ensure the accuracy of the postlayout simulation.
Use SIM_DSPF_MAX_ITER or SIM_SPEF_MAX_ITER
to set the maximum number of iterations for the second
run. If the active_node remains the same after the second
simulation run, HSPICE RF ignores these options.
For descriptions and usage examples, see .OPTION
SIM_DSPF_MAX_ITER and .OPTION
SIM_SPEF_MAX_ITER in the HSPICE Reference Manual:
Commands and Control Options.
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Additional Post-Layout Options
Other post-layout options are listed in Table 14.
Table 14
Additional Post-Layout Options
Syntax
Description
SIM_DSPF_RAIL
-orSIM_SPEF_RAIL
By default, HSPICE RF does not back-annotate parasitics
of the power-net. To back-annotate power-net parasitics,
include one of these options in the netlist.
Default=OFF. ON expands nets in a power rail as it expands
all nets.
SIM_DSPF_SCALER
SIM_SPEF_SCALER
-orSIM_DSPF_SCALEC
SIM_SPEF_SCALEC
Scales the resistance or capacitance values.
■
■
scaleR is the scale factor for resistance
scaleC is the scale factor for capacitance.
SIM_DSPF_LUMPCAPS If HSPICE RF cannot back-annotate an instance in a net
-orbecause one or more instances are missing in the
SIM_SPEF_LUMPCAPS hierarchical LVS ideal netlist, then by default HSPICE RF
does not evaluate the net. Instead of ignoring all parasitic
information for this net, HSPICE RF includes these options
to connect a lumped capacitor with a value equal to the net
capacitance to this net.
Default = ON adds lumped capacitance; ignores other net
contents.
SIM_DSPF_INSERROR HSPICE RF supports options to skip the unmatched
-orinstance, and continue the evaluation of the next instance.
SIM_SPEF_INSERROR
The default is OFF. ON skips unmatched instances and
continues the evaluation.
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Table 14
Additional Post-Layout Options (Continued)
Syntax
Description
SIM_SPEF_PARVALUE
This option affects only values in a SPEF file that have
triplet format: float:float:float, which this option interprets as
best:average:worst.
In such cases:
■
■
■
If SIM_SPEF_PARVALUE=1, HSPICE RF uses best.
If SIM_SPEF_PARVALUE=2 (default), HSPICE RF uses
average.
If SIM_SPEF_PARVALUE=3, HSPICE RF uses worst.
Unsupported SPEF Options
HSPICE RF does not yet support the following IEEE-481 SPEF options:
■
Hierarchical SPEF definition (multiple SPEF files connected with a
hierarchical definition):
■
*DEFINE and *PDEFINE
■
*R_NET and *R_PNET definition
■
*D_PNET definition.
Selective Extraction Flow
Use the selective extraction flow if disk space is limited. Especially use this
option when simulating a full-chip post-layout design, where block latency is
high. HSPICE RF feedbacks the active net information to Star-RCXT to extract
only the active parasitic.
The major advantage of this flow is a smaller DSPF or SPEF file, which saves
disk space.
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Star-RCXT
DSPF/SPEF
Post-Layout Flow
Ideal Netlist
OR
HSPICE RF
Active Nodes
Star-RCXT
DSPF/SPEF
Post-Layout Flow
Figure 25
Note:
Selective Extraction Flow
HSPICE RF generates an active node file in both Star-RC and
Star-RCXT format. It then expands the active node file to the
Star-RCXT command file to extract only active parasitics.
Overview of DSPF Files
In general, an SPF (Standard Parasitic Format) file describes interconnect
delay and loading, due to parasitic resistance and capacitance. DSPF (Detailed
Standard Parasitic Format) is a specific type of SPF file that describes the
actual parasitic resistance and capacitance components of a net. DSPF is a
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standard output format commonly used in many parasitic extraction tools,
including Star-RCXT. The HSPICE RF circuit simulator can read DSPF files.
DSPF File Structure
The DSPF standard is published by Open Verilog International (OVI). For
information about how to obtain the complete DSPF specification, or any other
documents from OVI, see:
http://www.ovi.org/document.html
The OVI DSPF specification requires the following file structure in a DSPF file.
Parameters in {braces} are optional:
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DSPF_file : :=
*|DSPF{version}
{*|DESIGN design_name}
{*|DATE date}
{*|VENDOR vendor}
{*|PROGRAM program_name}
{*|VERSION program_version}
{*|DIVIDER divider}
{*|DELIMITER delimiter}
.SUBCKT
*|GROUND_NET
{path divider} net_name
*|NET {path divider} net_name ||
{path divider} instance_name ||
pin_name
net_capacitance
*|P (pin_name pin_type
pinCap
{resistance {unit} {O}
capacitance {unit} {F}}
{x_coordinate y_coordinate})
||
*|I {path divider} instance_name
delimiter pin_name
{path divider} instance_name
pin_name pin_type
pinCap
{resistance {unit} {O}
capacitance {unit}{F}}
{x_coordinate y_coordinate}
*|S ({path divider} net_name ||
{path divider} instance_name
delimiter pin_name ||
pin_name
instance_number
{x_coordinate y_coordinate})
capacitor_statements
resistor_statements
subcircuit_call_statements
.ENDS
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{.END}
Table 15
DSPF Parameters
Parameter
Definition
*|DSPF
Specifies that the file is in DSPF format.
{version}
Version number of the DSPF specification (optional).
*|
Words that start with *| are keywords.
||
Or (use the option either preceding or following ||). For
example, *|P || *I means you can use either the *|P option or
the *|I option.
design_name
Name of your circuit design (optional).
date
Date and time when a parasitic extraction tool (such as StarRCXT) generated the DSPF file (optional).
vendor
Name of the vendor (such as Synopsys) whose tools you
used to generate the DSPF file (optional).
program_name
Name of the program (such as Star-RCXT) that generated
the DSPF file (optional).
program_version
Version number of the program that generated the DSPF file
(optional).
divider
Character that divides levels of hierarchy in a circuit path
(optional). If you do not define this parameter, the default
hierarchy divider is a slash (/). For example, X1/X2 indicates
that X2 is a subcircuit of the X1 circuit.
delimiter
Character used to separate the name of an instance and a
pin in a concatenated instance pin name, or a net name and
a sub-node number in a concatenated sub-node name. If you
do not define this parameter, the default delimiter is a colon
(:).
path
Hierarchical path to a net, instance, or pin, within a circuit.
net_name
Name of a net in a circuit or subcircuit.
instance_name
Name of an instance of a subcircuit.
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Table 15
DSPF Parameters (Continued)
Parameter
Definition
pin_name
Name of a pin on an instance of a subcircuit.
pinCap
Capacitance of a pin.
pin_type
■
■
■
■
■
■
resistance
I (input)
O (output)
B (bidirectional)
X (don’t care)
S (switch)
J (jumper)
Resistance on a pin in ohms for input (I), output (O), or
bidirectional (B) pins. You can use resistance-capacitance
(RC) pairs to model pin characteristics by using a higherorder equivalent RC ladder circuit than a single capacitor
model. For example: C0 {R1 C1 R2 C2...}. Attaching RC pairs
increases the order of the equivalent circuit from the first (C0)
order. For X, S, and J pin types, simulation ignores this
generalized capacitance value, but you should insert a 0
value as a place-holder for format integrity.
The resistance value can be a real number or an exponent
(optionally followed by a real number). You can enter an O
(ohms) after the value.
capacitance
Capacitance on a pin in farads for input (I), output (O), or
bidirectional (B) pins. Use as part of a resistancecapacitance (RC) pair. Optionally enter an F (farads) after the
value.
unit
■
■
■
■
■
■
292
K (kilo)
M (milli)
U (micro)
N (nano)
P (pico)
F (femto)
x_coordinate
Location of a pin relative to the x (horizontal) axis.
y_coordinate
Location of a pin relative to the y (vertical) axis.
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Table 15
DSPF Parameters (Continued)
Parameter
Definition
capacitor_ statements
SPICE-type statements that define capacitors in the
subcircuit.
resistor_ statements
SPICE-type statements that define resistors in the subcircuit.
subcircuit_call_
statements
Statements that call the subcircuit from higher-level circuits.
.END
Marks the end of the file (optional).
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DSPF File Example
*|DSPF 1.0
*|DESIGN "my_circuit"
*|DATE June 15, 2002 14:12:43
*|VENDOR "Synopsys"
*|PROGRAM "Star-RC"
*|VERSION "Star-RCXT 2002.2"
*|DIVIDER /
*|DELIMITER :
.SUBCKT BUFFER OUT IN
* Description of Nets
*GROUND_NET VSS
*|NET IN 1.221451PF
*|P(IN 1 0.0 0 10)
*|I(DF1:A DF1 A I 0.0PF 10.0 10.0)
*|I(DF1:B DF1 B I 0.0PF 10 0 20.0)
*|S(IN:1 5.0 10.0)(IN:2 5.0 20.0)
C1 IN VSS 0.117763PF
C2 IN:1 VSS 0.276325PF
C3 IN:2 VSS 0.286325PF
C4 DF1:A VSS 0.270519PF
C5 DF1:B VSS 0.270519PF
R20 IN N:1 1.70333E00
R21 IN:1 DF1:A 1.29167E-01
R22 IN:1 IN:2 1.29167E-01
R23 IN:2 DF1:B 1.70333E-01
*|NET BF 0.287069PF
*|I(DF1:C DF1 C O 0.0PF 12.0 15.0)
*|I(INV1:IN INV1 IN I 0.0PF 30.0 15.0)
C6 DF1:C VSS 0.208719PF
C7 INV1:IN VSS 0.783500PF
R24 DF1:C INV1:IN 1.80833E-01
*|NET OUT 0.148478PF
*|S(OUT:1 45.0 15.0)
*|P(OUT O 0.0PF 50.0 5.0)
*|I(INV1:OUT INV1 OUT O 0.0PF 40.0 15.0)
C8 INV1:OUT VSS 0.147069PF
C9 OUT:1 VSS 0.632813PF
C10 OUT VSS 0.776250PF
R25 INV1:OUT OUT:1 3.11000E00
R26 OUT:1 OUT 3.03333E00
* Description of Instances
XDF1 DF1:A DF1:B DF1:C DFF
XINV1 INV1:IN INV1:OUT INV
.ENDS
.END
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Overview of SPEF Files
The Standard Parasitics Exchange Format (SPEF) file structure is described in
IEEE standard IEEE-1481. For information about how to obtain the complete
SPEC (IEEE-1481) specification, or any other documents from IEEE, see:
http://www.ieee.org/products/onlinepubs/stand/standards.html
SPEF File Structure
The IEEE-1481 specification requires the following file structure in a SPEF file.
Parameters in [brackets] are optional:
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SPEF_file : :=
*SPEF version
*DESIGN design_name
*DATE date
*VENDOR vendor
*PROGRAM program_name
*VERSION program_version
*DESIGN_FLOW flow_type {flow_type}
*DIVIDER divider
*DELIMITER delimiter
*BUS_DELIMITER bus_prefix bus_suffix
*T_UNIT time_unit NS|PS
*C_UNIT capacitance_unit FF|PF
*R_UNIT resistance_unit OHM|KOHM
*L_UNIT inductance_unit HENRY|MH|UH
[*NAME_MAP name_index name_id|bit|path|name|physical_ref]
[*POWER_NETS logical_power_net physical_power_net ...]
[*GROUND_NETS ground_net ...]
[*PORTS logical_port I|B|O
*C coordinate ...
*L par_value
*S rising_slew falling_slew [low_threshold high_threshold]
*D cell_type]
[*PHYSICAL_PORTS [physical_instance delimiter]
physical_port I|B|O
*C coordinate ...
*L par_value
*S rising_slew falling_slew [low_threshold high_threshold]
*D cell_type]
[*DEFINE logical_instance design_name |
*PDEFINE physical_instance design_name]
*D_NET net_path total_capacitance
[*V routing_confidence]
[*CONN
*P [logical_instance delimiter] logical_port|physical_port
I|B|O
*C coordinate ...
*L par_value
*S rising_slew falling_slew
[low_threshold high_threshold]
*D cell_type
|
*I [physical_instance delimiter] logical_pin|physical_node
I|B|O
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*C coordinate ...
*L par_value
*S rising_slew falling_slew
[low_threshold high_threshold]
*D cell_type
*N net_name delimiter net_number coordinate
[*CAP cap_id node1 [node2] capacitance]
[*RES res_id node1 node2 resistance]
[*INDUC induc_id node1 node2 inductance]
*END
Table 16
SPEF Parameters
Parameter
Definition
*SPEF
Specifies that the file is in SPEF format.
{version}
Version number of the SPEF specification, such as “IEEE 14811998”.
*
Words that start with an asterisk (*) are keywords.
|
Or. For example, NS|PS means choose either nanoseconds or
picoseconds as the time units.
design_name
Name of your circuit design.
date
Date and time when a parasitic extraction tool (such as Star-RCXT)
generated the SPEF file.
vendor
Name of the vendor (such as Synopsys) whose tools you used to
generate the SPEF file (optional).
program_name
Name of the program (such as Star-RCXT) that generated the
SPEF file.
program_version
Version number of the program that generated the SPEF file.
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Table 16
SPEF Parameters (Continued)
Parameter
Definition
flow_type
One or more of the following flow types:
■
■
■
■
■
■
■
298
EXTERNAL_LOADS: The SPEF file defines all external loads (if
any). If you do not specify this flow type, then some or all external
loads are not defined in this SPEF file. If HSPICE RF cannot find
external load data outside the SPEF file, it reports an error.
EXTERNAL_SLEWS: The SPEF file defines all external slews (if
any). If you do not specify this flow type, then some or all external
slews are not defined in this SPEF file. If HSPICE RF cannot find
external slew data outside the SPEF file, it reports an error.
FULL_CONNECTIVITY: A SPEF file defines all net connectivity.
If you do not specify this flow type, then some or all net
connectivity is not defined in this SPEF file. If HSPICE RF cannot
find connectivity data outside the SPEF file, it issues an error.
This flow does not look for presence or absence of power and
ground nets, or any other nets that do not correspond to the
logical netlist. If a SPEC file includes FULL_CONNECTIVITY
and MISSING_NETS, HSPICE RF reports an error.
MISSING_NETS: If any logical nets are not defined in the netlist,
HSPICE RF merges missing parasitic data from another source.
If it does not find another source, HSPICE RF rereads the netlist
and estimates the missing parasitics. This flow does not look for
presence or absence of power and ground nets, or any other
nets that do not correspond to the logical netlist. If you use
FULL_CONNECTIVITY and MISSING_NETS in the same SPEF
file, HSPICE RF reports an error.
NETLIST_TYPE_VERILOG, NETLIST_TYPE_VHDL87,
NETLIST_TYPE_VHDL93, or NETLIST_TYPE_EDIF: Specifies
the type of naming conventions used in the SPEF file. If you
specify more than one format in one SPEF file, HSPICE RF
reports an error.
ROUTING_CONFIDENCE positive_integer: Specifies a default
routing confidence value for all nets in the SPEF file.
ROUTING_CONFIDENCE_ENTRY positive_integer
character_string: Specifies one or more characters that
represent additional routing confidence values, which you can
assign to nets in the SPEF file.
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Table 16
SPEF Parameters (Continued)
Parameter
Definition
flow_type
(continued)
■
■
■
divider
NAME_SCOPE LOCAL|FLAT: Specifies whether paths in the
SPEF file are LOCAL (relative to the current SPEF file) or FLAT
(relative to the top level of your circuit design).
SLEW_THRESHOLDS low high: Specifies low and high default
input slew thresholds for your circuit design as a percentage of
the voltage level for the input pin.
PIN_CAP NONE|INPUT_OUTPUT|INPUT_ONLY: Specifies the
type of pin capacitance to include when calculating the total
capacitance for all nets in the SPEF file, either no capacitance,
all input and output capacitances, or only input capacitances.
Character used to divide levels of hierarchy in a circuit path name.
Must be one of the following characters: . / : |
For example, X1/X2 means that X2 is a subcircuit of the X1 circuit.
delimiter
Character used to separate the name of an instance and a pin in a
concatenated instance pin name. Must be one of these characters:
./:|
bus_prefix
bus_suffix
Delimiter characters that precede and follow a bus bit or an arrayed
instance number. If these characters are not matching pairs,
HSPICE RF reports an error. Valid bus delimiter prefix and suffix
character pairs are brackets “[ ]”, braces “{ }”, parentheses “( )”, or
angle brackets “< >”>
time_unit
A positive number. For example, 10 PS means use time units of 10
picoseconds. 5 NS means use time units of 5 nanoseconds.
capacitance_unit
A positive number. For example, 10 PF means capacitance units of
10 picofarads. 5 FF means use capacitance units of 5
femtoseconds.
resistance_unit
Positive number. For example, 10 OHM sets resistance units to 10
ohms. 5 KOHM sets resistance units to 5 kilo ohms.
inductance_unit
A positive number. For example, 10 HENRY means use inductance
units of 10 henries. 5 MH means use inductance units of 5
millihenries. 2 UH means use inductance units of 2 micro-henries.
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Table 16
SPEF Parameters (Continued)
Parameter
Definition
name_index
Name used throughout a SPEF file. To reduce file space, you can
map other names to this name.
name_id|bit|path|name|
physical_ref
A name identifier, bit, path, name, or physical reference to map to
the name_index.
logical_power_net
Logical path (or logical path index) to a power net.
physical_power_net
Physical path (or physical path index) to a power net. You can
specify multiple logical_power_net physical_power_net pairs.
ground_net
Name of a net to use as a ground net. You can specify multiple
ground net names.
logical_port
Logical name of an input, output, or bidirectional port.
coordinate
Geometric location of a logical or physical port.
par_value
Either a single float value, or a triplet in float:float:float form.
rising_slew
Rising slew of the waveform for the port. T_UNIT defines the time
unit for the waveform.
falling_slew
Rising slew of the waveform for the port. T_UNIT defines the time
unit for the waveform.
low_threshold
Low voltage threshold as a percentage of the port’s input voltage.
Can bed one float value or a triplet in float:float:float form.
high_threshold
High voltage threshold as a percentage of the input voltage for the
port. Either a single float value or a triplet in float:float:float form.
cell_type
Type of cell that drives the port. If you do not know the cell type, use
the reserved word UNKNOWN_DRIVER as the cell type.
physical_port
Physical name of an input, output, or bidirectional port.
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Table 16
SPEF Parameters (Continued)
Parameter
Definition
logical_instance
Logical name of a subcircuit in your design_name circuit design.
You can specify more than one logical_instance. Whenever you
specify a logical instance name, you must set NAME_SCOPE to
FLAT. If you connect a logical net to a physical port, HSPICE RF
reports an error.
physical_instance
Physical name of a subcircuit in your design_name circuit design.
You can specify more than one physical_instance. Whenever you
specify a physical instance name, you must set NAME_SCOPE to
FLAT. If you connect a physical net to a logical port, HSPICE RF
reports an error.
routing_confidence
One of the following positive integers:
■
■
■
■
■
■
■
■
■
■
10: Statistical wire load model.
20: Physical wire load model.
30: Physical partitions with locations, no cell placement.
40: Estimated cell placement with Steiner tree-based route.
50: Estimated cell placement with global route.
60: Final cell placement with Steiner route.
70: Final cell placement with global route.
80: Final cell placement, final route, 2d extraction.
90: Final cell placement, final route, 2.5d extraction.
100: Final cell placement, final route, 3d extraction.
logical_pin
Logical name of a pin.
physical_node
Physical name of a node.
net_name
Name of a net in a circuit or subcircuit.
cap_id
Unique identifier for capacitance between two specific nodes.
res_id
Unique identifier for resistance between two specific nodes.
induc_id
Unique identifier for inductance between two specific nodes.
node1
First of two nodes, between which you are specifying a capacitance,
resistance, or inductance value.
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Table 16
SPEF Parameters (Continued)
Parameter
Definition
node2
Second of two nodes, between which you are specifying a
capacitance, resistance, or inductance value. For a capacitance
value, if you do not specify a second node name, HSPICE RF
assumes that the second node is ground.
capacitance
Specifies the capacitance value assigned to a cap_id identifier.
capacitance_unit defines the units of capacitance. For example, if
you set capacitance to 5 and capacitance_unit to 10 PF, then the
actual capacitance value is 50 picoFarads.
resistance
Specifies the resistance value assigned to a res_id identifier.
resistance_unit defines the units of resistance. For example, if you
set resistance to 5 and resistance_unit to 5 KOHM, then the actual
resistance value is 25 kilo ohms.
inductance
Specifies the resistance value assigned to an induc_id identifier.
inductance_unit defines the units of inductance. For example, if you
set inductance to 6 and inductance_unit to 2 UH, then the actual
inductance value is 12 microhenries.
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Post-Layout Back-Annotation
SPEF File Example
*SPEF "IEEE 1481-1998"
*DESIGN
"My_design"
*DATE
"11:26:34 Friday June 28, 2002"
*VENDOR
"Synopsys, Inc."
*PROGRAM
"Star-RCXT"
*VERSION
"2002.2."
*DESIGN_FLOW
"EXTERNAL_LOADS" "EXTERNAL_SLEWS" "MISSING_NETS"
*DIVIDER
/
*DELIMITER
:
*BUS_DELIMITER
[ ]
*T_UNIT
1 NS
*C_UNIT
1 PF
*R_UNIT
1 OHM
*L_UNIT
1 HENRY
*POWER_NETS
VDD
*GND_NETS
VSS
*PORTS
CONTROL O *L 30 *S 0 0
FARLOAD O *L 30 *S 0 0
INVX1FNTC_IN I *L 30 *S 5 5
NEARLOAD O *L 30 *S 0 0
TREE O *L 30 *S 0 0
If you use triplet format, the above section would look like this:
*PORTS
CONTROL O *L 30:30:30 *S 0:0:0 0:0:0
FARLOAD O *L 30:30:30 *S 0:0:0 0:0:0
INVX1FNTC_IN I *L 30:30:30 *S 5:5:5 5:5:5
NEARLOAD O *L 30:30:30 *S 0:0:0 0:0:0
TREE O *L 30:30:30 *S 0:0:0 0:0:0
This triplet formatting principle applies to the rest of this example.
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Post-Layout Back-Annotation
*D_NET INVX1FNTC_IN 0.033
*CONN
*P INVX1FNTC_IN I
*I FL_1281:A *L 0.033
*END
*D_NET INVX1FNTC 2.033341
*CONN
*I FL_1281:X
*I I1184:A I
*I FL_1000:A
*I NL_1000:A
*I TR_1000:A
O *L 0.0
*L 0.343
I *L 0.343
I *L 0.343
I *L 0.343
*CAP
216 FL_1000:A 0.346393
217 I1184:A 0.344053
218 INVX1FNTC_IN 0
219 INVX1FNTC_IN:10 0.154198
220 INVX1FNTC_IN:11 0.117827
221 INVX1FNTC_IN:12 0.463063
222 INVX1FNTC_IN:13 0.0384381
223 INVX1FNTC_IN:14 0.00246845
224 INVX1FNTC_IN:15 0.00350198
225 INVX1FNTC_IN:16 0.00226712
226 INVX1FNTC_IN:17 0.0426184
227 INVX1FNTC_IN:18 0.0209701
228 INVX1FNTC_IN:2 0.0699292
229 INVX1FNTC_IN:20 0.019987
230 INVX1FNTC_IN:21 0.0110279
231 INVX1FNTC_IN:24 0.0192603
232 INVX1FNTC_IN:25 0.0141824
233 INVX1FNTC_IN:3 0.0520437
234 INVX1FNTC_IN:4 0.0527105
235 INVX1FNTC_IN:5 0.1184749
236 INVX1FNTC_IN:6 0.0468458
237 INVX1FNTC_IN:7 0.0391578
238 INVX1FNTC_IN:8 0.0113856
239 INVX1FNTC_IN:9 0.0142528
240 NL_1000:A 0.344804
241 TR_000:A 0.34506
*RES
152 INVX1FNTC_IN INVX1FNTC_IN:18 8.39117
153 INVX1FNTC_IN INVX1FNTC_IN:5 25.1397
154 INVX1FNTC_IN:11 INVX1FNTC_IN:20 4.59517
155 INVX1FNTC_IN:12 INVX1FNTC_IN:13 3.688
156 INVX1FNTC_IN:13 INVX1FNTC_IN:17 25.102
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157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
INVX1FNTC_IN:14 INVX1FNTC_IN:16 0.0856444
INVX1FNTC_IN:14 NL_1000:A 0.804
INVX1FNTC_IN:15 INVX1FNTC_IN:16 1.73764
INVX1FNTC_IN:15 INVX1FNTC_IN:24 0.307175
INVX1FNTC_IN:17 INVX1FNTC_IN:25 5.65517
INVX1FNTC_IN:18 FL_1000:A 1/36317
INVX1FNTC_IN:2 INVX1FNTC_IN:4 6.95371
INVX1FNTC_IN:2 INVX1FNTC_IN:5 50.9942
INVX1FNTC_IN: INVX1FNTC_IN:21 4.71035
INVX1FNTC_IN: I1184:A 0.403175
INVX1FNTC_IN: TR_1000:A 0.923175
INVX1FNTC_IN: INVX1FNTC_IN:12 31.7256
INVX1FNTC_IN: INVX1FNTC_IN:4 11.9254
INVX1FNTC_IN: INVX1FNTC_IN:7 25.3618
INVX1FNTC_IN: INVX1FNTC_IN:6 23.3057
INVX1FNTC_IN: INVX1FNTC_IN:24 8.64717
INVX1FNTC_IN: INVX1FNTC_IN:8 7.46529
INVX1FNTC_IN: INVX1FNTC_IN:10 2.04729
INVX1FNTC_IN: INVX1FNTC_IN:10 10.8533
INVX1FNTC_IN: INVX1FNTC_IN:11 1.05164
*END
*D_NET NE_794 1.98538
*CONN
*I NL_1039:X O *L 0 *D INVX
*I NL_2039:A I *L 0.343
*I NL_1040:A I *L 0.343
*CAP
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
NE_794 0
NE_794:1 0.0792492
NE_794:10 0.0789158
NE_794:11 0.0789991
NE_794:12 0.0789991
NE_794:13 0.0792992
NE_794:14 0.00093352
NE_794:15 0.00063346
NE_794:16 0.0792992
NE_794:17 0.80116
NE_794:18 0.80116
NE_794:19 0.00125452
NE_794:2 0.0789158
NE_794:20 0.00336991
NE_794:21 0.00668512
NE_794:23 0.00294932
NE_794:25 0.00259882
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3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
NE_794:26 0.00184653
NE_794:3 0.0789158
NE_794:4 0.0796826
NE_794:5 0.0796826
NE_794:6 0.0789991
NE_794:7 0.0789991
NE_794:8 0.0793992
NE_794:9 0.0789158
NL_1039:X 0.00871972
NL_1040:A 0.344453
NL_2039:A 0.343427
*RES
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
NE_794:1 NE_794:13 66.1953
NE_794:1 NE_794:2 0.311289
NE_794:11 NE_794:12 0.311289
NE_794:13 NE_794:14 0.353289
NE_794:14 NE_794:19 0.365644
NE_794:15 NE_794:16 0.227289
NE_794:15 NE_794:20 0.239644
NE_794:17 NE_794:18 0.14
NE_794:19 NE_794:21 0.0511746
NE_794:2 NE_794:9 65.9153
NE_794:20 NE_794:23 1.15117
NE_794:21 NL_1039:X 3.01917
NE_794:25 NE_794:26 0.166349
NE_794:26 NL_1040:A 0.651175
NE_794:3 NE_794:10 65.9153
NE_794:3 NE_794:4 0.311289
NE_794:4 NE_794:17 66.5437
NE_794:5 NE_794:18 66.5437
NE_794:5 NE_794:6 0.311289
NE_794:6 NE_794:11 65.98853
NE_794:7 NE_794:12 65.9853
NE_794:7 NE_794:8 0.311289
NE_794:8 NE_794:16 66.3213
NE_794:9 NE_794:10 0.311289
NL_1039:X NE_794:25 1.00317
NL_2039:A NE_794:23 0.171175
*END
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Linear Acceleration
Linear Acceleration
Linear acceleration, by using the SIM_LA option, accelerates the simulation of
circuits that include large linear RC networks. To achieve this acceleration,
HSPICE RF reduces all matrices that represent RC networks. The result is a
smaller matrix that maintains the original port behavior, yet achieves significant
savings in memory and computation. Thus, the SIM_LA option is ideal for
circuits with large numbers of resistors and capacitors, such as clock trees,
power lines, or substrate networks.
In general, the RC elements are separated into their own network. The nodes
shared by both main circuit elements (including .PRINT, .PROBE,
and .MEASURE statements), and RC elements. are the port nodes of the RC
network,. All other RC nodes are internal nodes. The currents flowing into the
port nodes are a frequency-dependent function of the voltages at those nodes.
The multiport admittance of a network represents this relationship.
■
The SIM_LA option formulates matrices to represent multiport admittance.
■
Then, to eliminate as many internal nodes as possible, it reduces the size of
these matrices, while preserving the admittance, otherwise known as port
node behavior.
■
The amount of reduction depends on the f0 upper frequency, the threshold
frequency where SIM_LA preserves the admittance. This is shown
graphically in Figure 26.
admittance
nce
itta
m
d
a
ual
approx
act
f0
Figure 26
frequency
Multiport Admittance vs. Frequency
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Linear Acceleration
The SIM_LA option is very effective for post-layout simulation, because of the
volume of parasitics. For frequencies below f0, the approx signal matches that
of the original admittance. Above f0, the two waveforms diverge, but
presumably the higher frequencies are not of interest. The lower the f0
frequency, the greater the amount of reduction.
For the syntax and description of this control option, see .OPTION SIM_LA in
the HSPICE Reference Manual: Commands and Control Options.
You can choose one of two algorithms, explained in the following sections:
■
PACT Algorithm
■
PI Algorithm
PACT Algorithm
The PACT (Pole Analysis via Congruence Transforms) algorithm reduces the
RC networks in a well-conditioned manner, while preserving network stability.
■
The transform preserves the first two moments of admittance at DC (slope
and offset), so that DC behavior is correct (see Figure 27).
■
The algorithm preserves enough low-frequency poles from the original
network to maintain the circuit behavior up to a specified maximum
frequency f0, within the specified tolerance.
This approach is the most accurate of the two algorithms, and is the default.
admittance
d
rve
e
res
tp
e
ffs
do
n
ce
ea
ttan
i
p
m
o
sl
ad
ual
t
c
a
PACT: poles added
f0
Figure 27
308
frequency
PACT Algorithm
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Linear Acceleration
PI Algorithm
This algorithm creates a pi model of the RC network.
■
For a two-port, the pi model reduced network consists of:
•
a resistor connecting the two ports, and
•
a capacitor connecting each port to ground
The result resembles the Greek letter pi.
■
For a general multiport, SIM_LA preserves the DC admittance between the
ports, and the total capacitance that connects the ports to ground. All
floating capacitances are lumped to ground.
Linear Acceleration Control Options Summary
In addition to .OPTION SIM_LA, other options are available to control the
maximum resistance and minimum capacitance values to preserve, and to limit
the operating parameters of the PACT algorithm. Table 17 on page 309
contains a summary of these control options. For the syntax and descriptions of
these options, see the respective sections in the HSPICE and RF Netlist
Simulation Control Options in the HSPICE Reference Manual: Commands and
Control Options.
Table 17
PACT Options
Syntax
Description
.OPTION SIM_LA=PACT | PI
Activates linear matrix reduction and selects
between two methods.
.OPTION SIM_LA_FREQ=<value>
Upper frequency where you need accuracy
preserved. value is the upper frequency for
which the PACT algorithm preserves accuracy. If
value is 0, PACT drops all capacitors, because
only DC is of interest. The maximum frequency
required for accurate reduction depends on both
the technology of the circuit and the time scale
of interest. In general, the faster the circuit, the
higher the maximum frequency. The default is
1GHz.
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Linear Acceleration
Table 17
PACT Options (Continued)
Syntax
Description
.OPTION SIM_LA_MAXR=<value>
Maximum resistance for linear matrix reduction.
value is the maximum resistance preserved in
the reduction. SIM_LA assumes that any
resistor greater than value has an infinite
resistance, and drops the resistor after reduction
finishes. The default is 1e15 ohms.
.OPTION SIM_LA_MINC=<value>
Minimum capacitance for linear matrix
reduction. value is the minimum capacitance
preserved in the reduction. After reduction
completes, SIM_LA lumps any capacitor smaller
than value to ground. The default is 1e-16
farads.
.OPTION SIM_LA_MINMODE=
ON|OFF
Reduces the number of nodes instead of the
number of elements.
.OPTION SIM_LA_TIME=<value>
Minimum time for which accuracy must be
preserved. value is the minimum switching time
for which the PACT algorithm preserves
accuracy. HSPICE RF does not accurately
represent waveforms that occur more rapidly
than this time. SIM_LA_TIME is simply the dual
of SIM_LA_FREQ. The default is equivalent to
setting LA_FREQ=1 GHz. The default is 1ns.
.OPTION SIM_LA_TOL=<value>
Error tolerance for the PACT algorithm. value is
the error tolerance for the PACT algorithm, is
between 0.0 and 1.0. The default is 0.05.
Example
In this example, the circuit has a typical risetime of 1ns. Set the maximum
frequency to 1 GHz, or set the minimum switching time to 1ns.
.OPTION SIM_LA_FREQ = 1GHz
-or.OPTION SIM_LA_TIME = 1ns
However, if spikes occur in 0.1ns, HSPICE will not accurately simulate them. To
capture the behavior of the spikes, use:
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.OPTION SIM_LA_FREQ = 10GHz
-or.OPTION SIM_LA_TIME = 0.1ns
Note:
Higher frequencies (smaller times) increase accuracy, but only
up to the minimum time step used in HSPICE.
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13
Using HSPICE with HSPICE RF
Describes how various analysis features differ in HSPICE RF as compared to
standard HSPICE.
This first section of this chapter describes topics related to transient analysis
and the other section describe other differences between HSPICE and
HSPICE RF.
These topics are covered in the following sections
■
RF Numerical Integration Algorithm Control
■
RF Transient Analysis Accuracy Control
■
RF Transient Analysis Output File Formats
■
Compressing Analog Files
RF Numerical Integration Algorithm Control
In HSPICE RF, you can select either the Backward-Euler or Trapezoidal
integration algorithm. Each of these algorithms has its own advantages and
disadvantages for specific circuit types. For pre-charging simulation or timing
critical simulation, the Trapezoidal algorithm usually improves accuracy.
You use the SIM_ORDER option to control the amount of Backward-Euler (BE)
to mix with the Trapezoidal (TRAP) method for hybrid integration. For example,
.OPTION SIM_ORDER=x
Setting SIM_ORDER to its lowest value selects Backward-Euler integration
algorithm, and setting it to its highest value selects Trapezoidal integration.
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RF Transient Analysis Accuracy Control
For the syntax and description of this control option, see .OPTION
SIM_ORDER in the HSPICE Reference Manual: Commands and Control
Options.
RF Transient Analysis Accuracy Control
The default time step method in HSPICE RF mixes timestep algorithms
Trapezoidal and second-order Gear (Gear-2). This yields a more accurate
scheme than Trapezoidal or Backward-Euler. Also, detection of numerical
oscillations inserts fewer Backward-Euler steps than in previous HSPICE
versions.
The following sections discuss these topics:
■
.OPTION SIM_ACCURACY
■
Algorithm Control
.OPTION SIM_ACCURACY
You use the SIM_ACCURACY option to modify the size of timesteps in HSPICE
RF. For example,
.OPTION SIM_ACCURACY=val
A timestep is a time interval at which you evaluate a signal. HSPICE RF
discretely expresses the time continuum as a series of points. At each point or
timestep, a circuit simulator evaluates the corresponding voltage or current
value of a signal. Thus, a resulting signal waveform is a series of individual data
points; connecting these points results in a smooth curve.
You can apply different accuracy settings to different blocks or time intervals.
The syntax to set accuracy on a block, instance, or time interval is similar to the
settings used for a power supply.
Note:
An .OPTION SIM_ACCURACY takes precedence over
an.OPTION ACCURATE.
For the syntax and description of this control option, see .OPTION
SIM_ACCURACY in the HSPICE Reference Manual: Commands and Control
Options.
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RF Transient Analysis Accuracy Control
Algorithm Control
In HSPICE RF, you can select the Backward-Euler, Trapezoidal, Gear, or hybrid
method algorithms. Each of these algorithms has its own advantages and
disadvantages for specific circuit types. These methods have tradeoffs related
to accuracy, avoidance of numerical oscillations, and numerical damping of
circuit oscillations. For pre-charging simulation or timing critical simulations, the
Trapezoidal algorithm usually improves accuracy.
.OPTION METHOD
You use the METHOD option to select a numeric integration method for a
transient analysis.
HSPICE RF supports three basic timestep algorithms: Trapezoidal (TRAP),
second-order Gear (Gear-2), and Backward-Euler (BE). Backward-Euler is the
same as first-order Gear. Also, HSPICE RF supports a hybrid algorithm
(TRAPGEAR), which is a mixture of the three basic algorithms.
HSPICE RF contains an algorithm for auto-detection of numerical oscillations
commonly encountered with trapezoidal integration. If HSPICE RF detects
such oscillations, it inserts BE steps, but not more than one BE step for every
10 time steps. To turn off auto-detection, use the PURETP option.
The TRAPGEAR method, combining 90% trapezoidal with 10% Gear-2. HSPICE
RF inserts BE steps, when the simulator encounters a breakpoint, or when the
auto-detection algorithm finds numerical oscillations.
For the syntax and description of this control option, see .OPTION METHOD in
the HSPICE Reference Manual: Commands and Control Options.
.OPTION MAXORD
You use the MAXORD option to select the maximum order of integration for the
GEAR method. Either the first-order Gear (Backward-Euler), or the secondorder Gear (Gear-2) integration method.
For the syntax and description of this control option, see .OPTION MAXORD in
the HSPICE Reference Manual: Commands and Control Options.
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RF Transient Analysis Accuracy Control
.OPTION SIM_ORDER
You use the SIM_ORDER option to control the amount of Backward-Euler (BE)
to mix with the Trapezoidal method for hybrid integration. This option affects
time stepping when you set .OPTION METHOD to TRAP or TRAPGEAR.
For the syntax and description of this control option, see .OPTION
SIM_ORDER in the HSPICE Reference Manual: Commands and Control
Options.
.OPTION SIM_TG_THETA
You use the SIM_TG_THETA option to control the amount of Gear-2 method to
mix with trapezoidal integration for the hybrid TRAPGEAR method.
For the syntax and description of this control option, see .OPTION
SIM_TG_THETA in the HSPICE Reference Manual: Commands and Control
Options.
.OPTION SIM_TRAP
You use the SIM_TRAP option to change the default SIM_TG_THETA to 0, so
that method=trapgear acts like METHOD=TRAP.
For the syntax and description of this control option, see .OPTION SIM_TRAP
in the HSPICE Reference Manual: Commands and Control Options.
.OPTION PURETP
You use the PURETP option to turn off insertion of Backward-Euler (BE) steps
due to auto-detection of numerical oscillations.
For the syntax and description of this control option, see .OPTION PURETP in
the HSPICE Reference Manual: Commands and Control Options.
.OPTION SIM_OSC_DETECT_TOL
You use the SIM_OSC_DETECT_TOL option to specify the tolerance for
detecting numerical oscillations. If HSPICE RF detects numerical oscillations, it
inserts Backward-Euler (BE) steps. Smaller values of this tolerance result in
fewer BE steps.
For the syntax and description of this control option, see .OPTION
SIM_OSC_DETECT_TOL in the HSPICE Reference Manual: Commands and
Control Options.
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RF Transient Analysis Output File Formats
RF Transient Analysis Output File Formats
The default output format for transient analysis in HSPICE RF is the same as in
HSPICE: the .tr0 file format. See Transient Analysis in the HSPICE User Guide:
Simulation and Analysis. HSPICE RF supports these output formats, which are
described in this section:
■
Tabulated Data Output
■
WDB Output Format
■
NW Output Format
■
VCD Output Format
■
turboWave Output Format (tw)
■
Undertow Output Format (ut)
■
CSDF Output Format
If your netlist includes an unsupported output format, HSPICE RF prints a
warning message, indicating that the selected format is unsupported. HSPICE
RF then automatically defaults the output to TR0 format.
Waveform Results
The waveform results of Monte Carlo runs are expected to be different in
HSPICE vs. RF because the results depend on the exact sequence in which
the random numbers are used, and it is not practical to make them the same.
However, if you run a large number of samples, the statistical results from
HSPICE and RF should converge to the same values.
Tabulated Data Output
HSPICE RF outputs all analog waveforms specified in a .PRINT statement.
HSPICE RF saves these waveforms as ASCII tabulated data, into a file with
the .PRINT extension.
To display waveforms graphically, Custom WaveView can directly read the
tabulated data. For more information about Custom WaveView, see the
CustomExplorer and Custom WaveView User Guide.
Note:
Tabulated data excludes waveforms specified in .PROBE
statements.
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RF Transient Analysis Output File Formats
WDB Output Format
You can use the waveform database (WDB) output format in .OPTION POST. It
was developed for maximum efficiency. The output file is *.wdb#. For example,
to output to a *.wdb# file, enter:
.OPTION POST=wdba
Signals across multiple hierarchies, that map to the same node, are named
together. They also share the same waveform data.
You can also set up the database so that Custom WaveView extracts one signal
at a time. This means that Custom WaveView does not need to read the entire
output file to display a single waveform.
The WDB format was designed to make accessing waveform data faster and
more efficient. It is a true database so the waveform browser does not have to
load the complete waveform file for you to view a single signal. This feature is
especially useful if the size of the waveform file is several gigabytes.
Furthermore, the WDB format is usually more compact than XP and NW
(described later in this section). However, if the NW file is already very small,
then WDB offers little advantage in size or speed.
You can compress WDB files. For additional information, see Compressing
Analog Files on page 320.
TR Output Format
HSPICE RF stores simulation results for analysis by using the Custom
WaveView graphical interface method. For example, these commands output a
*.tr# file in TR format:
■
.OPTION POST=1 saves the results in binary format
■
.OPTION POST=2 saves the results in ASCII format.
NW Output Format
HSPICE RF outputs the NW format to a file with the .nw# extension. You need
a Synopsys waveform display tool to process a file in NW format. For example,
to output to a *.nw# file, enter:
.OPTION POST=nw
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RF Transient Analysis Output File Formats
You can compress NW files. For additional information, see Compressing
Analog Files on page 320.
VCD Output Format
To output your waveforms from HSPICE RF in VCD (Value Change Dump)
format, set the VCD option in conjunction with the .LPRINT statement. For
example,
.OPTION VCD
.LPRINT (0.5 4.5) v(0) v(2) v(6)
.LPRINT Statement
You use the .LPRINT statement to produce output in VCD file format from
transient analysis. For example,
.LPRINT (v1,v2) output_varable_list
For additional information, see .LPRINT in the HSPICE Reference Manual:
Commands and Control Options.
turboWave Output Format
To use turboWave output format TW, enter:
.OPTION POST=tw
This format supports analog compression as described in Compressing Analog
Files on page 320.
Undertow Output Format
To use Veritools Undertow output format UT, enter:
.OPTION POST=ut
This format supports analog compression as described in Compressing Analog
Files on page 320.
The waveform list in UT format now displays in a hierarchical structure, rather
than one flat level as in previous versions.
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Compressing Analog Files
CSDF Output Format
To use CSDF output format CSDF, enter:
.OPTION POST=csdf
.OPTION csdf [overrides .OPTION POST setting]
Compressing Analog Files
Analog compression eliminates unnecessary data points from a HSPICE RF
voltage or current waveform to reduce the size of the waveform file.
Eliminating Voltage Datapoints
You use the SIM_DELTAV option to determine the selection criteria for HSPICE
RF voltage waveforms in WDB or NW format. For example,
.OPTION SIM_DELTAV=<value>
During simulation, HSPICE RF checks whether the value of the X signal at the
n timestep changes by more than the SIM_DELTAV option, from its previous
value at the n-1 timestep.
■
If yes, then HSPICE RF saves the new data point.
■
Otherwise, this new data point is lost.
Typically such an algorithm yields a reduced file size with minimal resolution
loss as long as you set an appropriate SIM_DELTAV value. If a value for the
SIM_DELTAV option is too large, the waveform degrades.
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NW and WDB both eliminate these data points,
which are within DELTAV or DELTAI of the previous
data point, and are not ON the plotted waveform line.
Figure 28
NW retains these data
points that are ON the line,
plotting 3 segments. But
WDB eliminates these data
points, plotting only ONE
segment for this line.
Analog Compression Formats
For a additional information, see .OPTION SIM_DELTAV in the HSPICE
Reference Manual: Commands and Control Options.
Eliminating Current Datapoints
You use the SIM_DELTAI option to determine the selection criteria for HSPICE
RF current waveforms in WDB or NW format. For example,
.OPTION SIM_DELTAI=val
For a additional information, see .OPTION SIM_DELTAI in the HSPICE
Reference Manual: Commands and Control Options.
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Advanced Features
14
Describes how to invoke HSPICE RF and how to perform advanced tasks,
including redirecting input and output.
HSPICE RF accepts a netlist file from standard input and delivers the ASCII
text simulation results to an HTML file or to stdout. Error and warning
messages are forwarded to standard error output.
This chapter describes how to do this as well as how to invoke HSPICE RF and
redirect input and output.
These topics are covered in the following sections:
■
Creating a Configuration File
■
Using Wildcards in HSPICE RF
■
Limiting Output Data Size
■
Probing Subcircuit Currents
■
Generating Measurement Output Files
■
Optimization
■
Using CHECK Statements
■
POWER DC Analysis
■
Detecting and Reporting Surge Currents
Creating a Configuration File
You can create a configuration file, called .hspicerf, to customize your HSPICE
RF simulation. HSPICE RF first searches for .hspicerf in your current working
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directory, then in your home directory as defined by $HOME. The configuration
options listed in Table 18 are available for your use.
Table 18
Configuration File Options
Keyword
Description
Example
flush_waveform
Flushes a waveform. If you do not specify a
percentage, then the default value is 20%.
flush_waveform
percent%
ground_floating_
node
Uses .IC statements to set floating nodes in a
ground_floating_
circuit to ground. You can select three options for node 1
grounding floating nodes:
■
■
■
If set to 1, grounds only floating nodes
(gates, bulk, control nodes, non-rail bulk) that
are included in the .IC set.
If set to 2, adds unconnected terminals to this
set.
If set to 3, uses .IC statements to ground all
floating nodes, including dangling terminals.
hier_delimiter
Changes the delimiter for subcircuit hierarchies hier_delimiter /
from “.” to the specified symbol.
html
Stores all HSPICE RF output in HTML format.
htmlhspicerf
test
This example creates
a file named test.html
in the current directory.
integer_node
Removes leading zeros from node names. For
example, HSPICE RF considers 0002 and 2 to
be the same node.
integer_node
Without this keyword, 0002 and 2 are two
separate nodes.
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Table 18
Configuration File Options (Continued)
Keyword
Description
max_waveform_size
Automatically limits the waveform file size.
■
■
■
Example
max_waveform_
If the number is less than 5000, HSPICE RF size 2000000000
resets it to 2G.
If you do not set the number, HSPICE RF
uses the default, 2G.
If you do not set the line, the file size has no
limit.
negative_td
Allows negative time delay input in pwl
(piecewise linear with repeat), pl (piecewise
linear), exp (exponential, rising time delay only),
sin (damped sinusoidal), pulse (trapezoidal
pulse), and am (amplitude modulation) formats.
If you do not set
negative_td, a
negative time delay
defaults to zero.
port_element_
voltage_ matchload
Allows the alternate Port element definition. A
Port element consists of a voltage source in
series with a resistor.
port_element_
voltage_
matchload
For the explanation that follows, let the userspecified DC, AC, or transient value of the Port
element be V, and let the voltage across the
overall port element be Vp.
By default, HSPICE RF will set the internal
voltage source value to V. The value of Vp will be
lower than V, depending on the internal
impedance and the network's input impedance.
With the alternate definition, the internal voltage
source value is adjusted to 2*V, so that Vp=V
when the Port element's impedance is matched
with the network input impedance. The actual
value of Vp will still depend on the port and
network impedances.
rcxt_divider
Defines the hierarchy delimiter in the active
nodes file in RCXT format.
skip_nrd_nrs
Directs HSPICE RF to consider transistors with skip_nrd_nrs
matching geometries (except for NRD and NRS)
as identical for pre-characterization purposes.
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Table 18
Configuration File Options (Continued)
Keyword
Description
Example
unit_atto
Activates detection of the “atto.” unit. Otherwise, unit_atto
HSPICE RF assumes that “a” represents
“amperes.”
v_supply
Changes the default voltage supply range for
characterization.
v_supply 3
wildcard_left_range
Begins range expression.
wildcard_left_
range [
wildcard_match_all
Matches any group of characters.
wildcard_match_
all *
wildcard_match_one
Matches any single character.
wildcard_match_
one ?
wildcard_right_range Ends range expression.
Note:
wildcard_right_
range ]
For more information about wildcards, see Using Wildcards in
HSPICE RF on page 327.
Inserting Comments in a .hspice File
To insert comments into your .hspicerf file, include a number sign character (#)
as the first character in a line. For example, this configuration file shows how to
use comments in a .hspicerf file:
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# sample configuration file
# the next line of code changes the delimiter
# for subcircuit hierarchies from "," to "^"
hier_delimiter ^
# the next line of code matches any groups of "*" characters
wildcard_match_all *
# the next line of code matches one "?" character
wildcard_match_one ?
# the next line of code begins the range expression with
# the "[" character
wildcard_left_range [
# the next line of code ends the range expression with
# the "]" character
wildcard_right_range ]
Using Wildcards in HSPICE RF
You can use wildcards to match node names. HSPICE RF uses wildcards
somewhat differently than standard HSPICE.
Before using wildcards, you must define the wildcard configuration in
a .hspicerf file. For example, you can define the following wildcards in
a .hspicerf file:
file .hspicerf
wildcard_match_one
wildcard_match_all
wildcard_left_range
wildcard_right_range
?
*
[
]
The .PRINT, .PROBE, .LPRINT, and .CHECK statements support wildcards in
HSPICE RF.
For more information about using wildcards in an HSPICE configuration file,
see Using Wildcards in PRINT and PROBE Statements in the HSPICE User
Guide: Simulation and Analysis.
Limiting Output Data Size
For multi-million transistor simulations, an unrestricted waveform file can grow
to several gigabytes in size. The file becomes unreadable in some waveform
viewers, and requires excessive space on the hard drive.
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Limiting Output Data Size
This section describes options that limit the number of nodes output to the
waveform file to reduce the file size. HSPICE RF supports the following options
to control the output:
■
SIM_POSTTOP Option
■
SIM_POSTSKIP Option
■
SIM_POSTAT Option
■
SIM_POSTDOWN Option
■
SIM_POSTSCOPE Option
SIM_POSTTOP Option
You use the SIM_POSTTOP option to limit the data written to your waveform file
to data from only the top n level nodes. This option outputs instances up to n
levels deep. For example,
.OPTION SIM_POSTTOP=<n>
Note:
To enable the waveform display interface, you also need the
POST option.
For additional information, see .OPTION SIM_POSTTOP in the HSPICE and
HSPICE RF Command Reference.
SIM_POSTSKIP Option
You use the SIM_POSTSKIP to have the SIM_POSTTOP option skip any
instances and their children that the subckt_definition defines. For example,
.OPTION SIM_POSTSKIP=<subckt_definition>
For additional information, see .OPTION SIM_POSTSKIP in the HSPICE and
HSPICE RF Command Reference.
SIM_POSTAT Option
You use the SIM_POSTAT
option to limit the waveform output to only the nodes in the specified subcircuit
instance. For example,
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.OPTION SIM_POSTAT=<instance>
This option can be used in conjunction with the SIM_POSTTOP option and
when present, has precedence over the SIM_POSTSKIP option.
For additional information, see .OPTION SIM_POSTAT in the HSPICE and
HSPICE RF Command Reference.
SIM_POSTDOWN Option
You use the SIM_POSTDOWN option to include an instance and all children of
that instance in the output. For example,
.OPTION SIM_POSTDOWN=<instance>
It can be used in conjunction with the SIM_POSTTOP option and when present,
has precedence over the SIM_POSTSKIP option.
For additional information, see .OPTION SIM_POSTDOWN in the HSPICE and
HSPICE RF Command Reference.
SIM_POSTSCOPE Option
You use the SIM_POSTSCOPE option to specify the signal types to probe from
within a scope. For example,
.OPTION SIM_POSTSCOPE=net|port|all
For additional information, see .OPTION SIM_POSTSCOPE in the HSPICE
and HSPICE RF Command Reference.
Probing Subcircuit Currents
To provide subcircuit power probing utilities, HSPICE RF uses the X() and X0()
extended output variables. You can use these X variables in .PROBE, .PRINT,
or .MEASURE statements.
The following syntax is for the output variable X():
X (subcircuit_node_path)
X0 (subcircuit_node_path)
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subcircuit_node_path specifies the subcircuit path and the subcircuit node
name definition. The node must be either an external node in a subcircuit
definition or a global node.
X() returns the total current flowing into a subcircuit branch, including all lower
subcircuit hierarchies. X0() returns only current flowing into a subcircuit branch,
minus any current flowing into lower subcircuit hierarchies. Figure 29 on
page 330 illustrates the difference between the X() and X0 () variables.
The dotted line boxes represent subcircuits, and the black circles are the
external nodes. The X(X1.vc1) path returns the current of the X1subcircuit,
through the vc1 node, including the current to the X1.X1 and X1.X2 subcircuits
as represented by the white (black outlined) arrows. In contrast, X0(X1.vc2)
returns only the current flowing through vc2 to the top level of the X1 subcircuit
as shown by the black arrows.
VDD1
VDD2
X0(X1.vc2)
X(X1.vc1)
vc1
X(X2.vd2)
vc2
X1
vd1
vd2
X2
X1.X1
X1.X2
Figure 29
Probing Subcircuit Currents
Example 1
In this example, the first five lines constitute the definition of the sb1 subcircuit
with external nodes named node1, node2, and clr. The line beginning with
X1 is an instance of sb1 with nodes named;
330
■
11 (references node1)
■
12 (references node2)
■
0 (references clr)
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.subckt sb1 node1 node2 clr
* subckt elements
R1 node1 node2 1K
C1 clr node1 1U
.ends
* subcircuit instance
X1 11 12 0 sb1
.PRINT X(X1.node1) ‘X(X1.clr) + I(X1.R1)’
To find the current flowing into node 11 of the X1 subcircuit instance, this
example uses the X() variable. HSPICE RF maps node 11 to the node1
external node as shown in the first part of the .PRINT statement.
The latter half of the .PRINT statement illustrates that you can combine the
X() variable with I() variables.
Example 2
In this example, the X() variable finds the current through the in node of the S1
subcircuit.
.subckt S1 in out
R1 in inp 1K
C1 inp 0 1u
R2 in out 1K
.PROBE X(in)
.ends
Generating Measurement Output Files
You can make all of the same measurements with the .MEASURE statement in
HSPICE RF as you can in HSPICE.
The results of the .MEASURE statements appear in a file with one of the
following filename extensions:
■
.mt# for measurements in transient analysis
■
.ms# for measurements in DC analysis
■
.ma# for measurements in AC analysis
■
.mb# for measurements in HB analysis
■
.mp# for measurements in HBNOISE analysis
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Optimization
For more information about .MEASURE statements, see HSPICE and HSPICE
RF Netlist Commands in the HSPICE Reference Manual: Commands and
Control Options.
Optimization
Like HSPICE, HSPICE RF employs an incremental optimization technique.
This technique solves the DC parameters first, then the AC parameters, and
finally the transient parameters.
To perform optimization, create an input netlist file that specifies:
■
Optimization parameters with upper and lower boundary values along with
an initial guess.
■
An AC, DC, TRAN, HB, or HBOSC optimization statement.
■
An optimization model statement.
■
Optimization measurement statements for optimization parameters.
If you provide the input netlist file, optimization specifications, limits, and initial
guess, then the optimizer reiterates the simulation until it finds an optimized
solution.
Usage Notes and Examples
■
Optimization works for TRAN, AC, DC, HB, HBOSC, and HBAC analyses.
■
You can add the GOAL options in every meaningful .MEASURE statement,
like FIND-WHEN, FIND-AT, and so forth.
■
A data sweep is not required to be defined in the .HB statement for HB
optimization to use the measured result from .MEASURE HBNOISE,
PHASENOISE, or HBTRAN statements. Therefore, parameter sweep is not
supported for this type of optimization.
■
Optimize multiple parameters with multiple goals by selecting .MODEL OPT
LEVEL=0 (modified Lavenberg-Marquardt method).
■
Optimize single parameters in single measurement situations by selecting
.MODEL OPT LEVEL=1 (bisection method).
■
Examples
•
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Optimization
.param W=opt1(231u, 100u, 800u)
.param Rs=opt1(10,8,20)
•
Optimization analysis statement
.HB tones=2.25g 2.5g nharms=6,3
+ sweep Pin:dbm -30 0 2
+ sweep optimize = opt1
+ results = gain $measure result to tune the parameters
+ model= optmod1
•
Selecting an optimization model
.model optmod1 opt level=1 $Bisection method
+ itropt=40 relin=1e-4 relout=1e-6 $ accuracy settings
•
Measurement statements to tune the optimization parameters
.measure HB vif find vdb(if+)[-1,1] at 10e-6
.measure HB vrf find vdb(rf+)[0,1] at 10e-6
.measure HB gain=param('vif-vrf') goal=-2
•
Measurement statement to find the fundamental frequency from HB
analysis
.measure HB frequency_max FIND ‘HERTZ[1]’ at=0
Optimizing AC, DC. and TRAN Analyses
The HSPICE syntax is followed for optimizing AC, DC. and TRAN analyses.
The required statements are:
■
Optimization .PARAM statement
.PARAM ParamName=OPTxxx(Init,LoLim,HiLim)
■
Optimizing .TRAN statement
.TRAN tincr1 tstop1 [tincr2 tstop2 ... tincrN tstopN]
+ SWEEP OPTIMIZE=OPTxxx RESULTS=measname MODEL=optmod
■
Optimizing .MODEL statement
.MODEL mname OPT LEVEL=[0|1]
Where:
•
0 specifies the Modified Levenberg-Marquardt method. You would use
this setting with multiple optimization parameters and goals.
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•
1 specifies the Bisection method. You would use this setting with one
optimization parameter.
Optimizing HB Analysis
■
Optimization with HB Measurements
■
Optimization with HBNOISE, PHASENOISE, or HBTRAN Measurements
Optimization with HB Measurements
The required statements are:
■
Analysis statement
.HB TONES=f1[f2 ... fn] [NHARMS=h1 [,h2 ... hn]]
+ SWEEP parameter_sweep OPTIMIZE=OPTxxx RESULT=measname
+ MODEL=mname
■
Measure statement
.MEASURE HB measname FIND out_var1 AT=val GOAL=val
Optimization with HBNOISE, PHASENOISE, or HBTRAN
Measurements
The required statements are:
■
Analysis statement
.HB TONES=f1[f2 ... fn] [NHARMS=h1 [,h2 ... hn]]
+ SWEEP OPTIMIZE=OPTxxx RESULT=measname MODEL=mname
For example,
.HBOSC tones=1g nharms = 5 optimize = opt1
+ result = y1, y2 model = m1
.model m1 opt level=0
.PHASENOISE dec 1 1k 1g
.meas phasenoise y1 find phnoise at 10k goal = -150dbc
.meas phasenoise y2 RMSJITTER phnoise units = sec goal =
1.0e-12
■
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.MEASURE HBNOISE measname FIND out_var1 AT=val GOAL=val
.MEASURE PHASENOISE measname FIND out_var1 AT=val
+ GOAL=val
.MEASURE HBTRAN measname FIND out_var1 AT=val GOAL=val
Optimizing HBOSC Analysis
■
Optimization with HB Measurements
■
Optimization with HBNOISE, PHASENOISE, or HBTRAN Measurements
Optimization with HB Measurements
The required statements are:
■
Analysis statement
.HBOSC TONES=f1 [f2 ... fn] [NHARMS=h1 [,h2 ... hn]]
+ SWEEP parameter_sweep OPTIMIZE=OPTxxx RESULT=measname
+ MODEL=mname
■
Measure statement
.MEASURE HB measname FIND out_var1 AT=val GOAL=val
Optimization with HBNOISE, PHASENOISE, or HBTRAN
Measurements
The required statements are:
■
Analysis statement
.HBOSC TONES=f1 [f2 ... fn] [NHARMS=h1 [,h2 ... hn]]
+ SWEEP OPTIMIZE=OPTxxx RESULT=measname MODEL=mname
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For example,
.HBOSC tones=1g nharms = 5 sweep x 1 5 1 optimize = opt1
+ result = y1, y2 model = m1
.model m1 opt level=0
.PHASENOISE dec 1 1k 1g
.meas phasenoise y1 find phnoise at 10k goal = -150dbc
.meas phasenoise y2 RMSJITTER phnoise units = sec goal =
1.0e-12
Measure statement—
.MEASURE HBNOISE measname FIND out_var1 AT=val GOAL=val
.MEASURE PHASENOISE measname FIND out_var1 AT=val
+ GOAL=val
.MEASURE HBTRAN measname FIND out_var1 AT=val GOAL=val
Optimization with HBNOISE, PHASENOISE or HBTRAN measurements must
not be used in combination with HB measurement optimization as shown in
Optimization with HB Measurements.
Using CHECK Statements
The CHECK statements in HSPICE RF offer the following instrumentation:
■
Setting Global Hi/Lo Levels
■
Slew, Rise, and Fall Conditions
■
Edge Timing Verification
■
Setup and Hold Verification
■
IR Drop Detection
The results of these statements appear in a file with an .err extension. To
prevent creating unwieldy files, HSPICE RF reports only the first 10 violations
for a particular check in the .err file.
Setting Global Hi/Lo Levels
You use the .CHECK GLOBAL_LEVEL statement to globally set the desired
high and low definitions for all CHECK statements. For example,
.CHECK GLOBAL_LEVEL (hi lo hi_th lo_th)
Values for hi, lo, and the thresholds are defined by using this statement.
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For syntax and description of this statement, see .CHECK GLOBAL_LEVEL in
the HSPICE Reference Manual: Commands and Control Options.
Slew, Rise, and Fall Conditions
You use the .CHECK SLEW statement to verify that a slew rate occurs within
the specified window of time. For example,
.CHECK SLEW (min max) node1 [node2 ...] [(hi lo hi_th lo_th)]
3.3
2.6
0.7
0.0
1ns < t < 3ns
Figure 30
SLEW Example
For syntax and description of this statement, see .CHECK SLEW in the
HSPICE Reference Manual: Commands and Control Options.
You use the .CHECK RISE statement to verify that a rise time occurs within the
specified window of time. For example,
.CHECK RISE (min max) node1 [node2 ...] [(hi lo hi_th lo_th)]
HI
HI_thresh
LO_thresh
LO
1.5 ns < t < 2.2 ns
Figure 31
RISE Time Example
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Using CHECK Statements
For syntax and description of this statement, see .CHECK RISE in the HSPICE
and HSPICE RF Command Reference.
You use the .CHECK FALL statement to verify that a fall time occurs within the
specified window of time. For example,
.CHECK FALL (min max) node1 [node2 ...>] [(hi lo hi_th lo_th)]
For syntax and description of this statement, see .CHECK FALL in the HSPICE
Reference Manual: Commands and Control Options.
Edge Timing Verification
The edge condition verifies that a triggering event provokes an appropriate
RISE or FALL action, within the specified time window. You use the .CHECK
EDGE statement to verify this condition. For example,
.CHECK EDGE (ref RISE|FALL min max RISE|FALL)
+ node1 [node2 . . . ] [(hi lo hi_th low_th)]
voutA
CLK
HI
HI_thresh
LO_thresh
LO
1ns < t < 3 ns
Figure 32
EDGE Example
For syntax and description of this statement, see .CHECK EDGE in the
HSPICE and HSPICE RF Command Reference.
Setup and Hold Verification
You use the .CHECK SETUP and .CHECK HOLD statements to ensure that
specified signals do not switch for a specified period of time. For example,
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.CHECK SETUP (ref RISE|FALL duration RISE|FALL) node1
+[node2 . . . ] [(hi lo hi_th low_th)]
.CHECK HOLD (ref RISE|FALL duration RISE|FALL) node1
+[node2 . . . ] [(hi lo hi_th low_th)]
■
For a SETUP condition, this is the minimum time before the triggering event,
during which the specified nodes cannot rise or fall.
nodeA
v1
HI
HI_thresh
LO_thresh
LO
t >=2ns
Figure 33
SETUP Example
For syntax and description of this statement, see .CHECK SETUP in the
HSPICE Reference Manual: Commands and Control Options.
■
For a HOLD condition, this is minimum time required after the triggering
event, before the specified nodes can rise or fall.
vin*
nodeA
HI
HI_thresh
LO_thresh
LO
t >=2ns
Figure 34
HOLD Example
For syntax and description of this statement, see .CHECK HOLD in the
HSPICE and HSPICE RF Command Reference.
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POWER DC Analysis
IR Drop Detection
You use the .CHECK IRDROP statement to verify that the IR drop does not
exceed, or does not fall below, a specified value for a specified duration. For
example,
.CHECK IRDROP ( volt_val time ) node1 [node2 . . . ]
+ [( hi lo hi_th low_th )]
v1
-2 volts
t <=1ns
Figure 35
IR Drop Example
For syntax and description of this statement, see .CHECK IRDROP in the
HSPICE Reference Manual: Commands and Control Options.
POWER DC Analysis
You use the .POWERDC (standby current) statement to calculate the DC
leakage current of a design hierarchy. For example,
.POWERDC keyword subckt_name1...
This statement creates a table that lists the measurements of the AVG, MAX,
and MIN values for the current of every instance in the subcircuit. This table
also lists the sum of the power of each port in the subcircuit.
You use the SIM_POWERDC_HSPICE option to increase the accuracy of
operating point (OP) calculations.
Or for even higher accuracy in operating point calculations, you use the
SIM_POWERDC_ACCURACY option.
For syntax and description of this statement and options, see .POWERDC,
.OPTION SIM_POWERDC_ACCURACY, or .OPTION
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SIM_POWERDC_HSPICE in the HSPICE Reference Manual: Commands and
Control Options.
Power DC Analysis Output Format
*** Leakage Current Result ***
Subckt Name=XXX
Instance Name
Port
Max(A)
Min(A)
Avg(A)
Total Power
Max(W)
Min(W)
Avg(W)
NOTE:
Power=Sum{Ii * Vi}
Subckt Name=XXX
Instance Name
Port
Max(A)
Min(A)
Avg(A)
Total Power
Max(W)
Min(W)
Avg(W)
Example
.global vdd vss
.powerdc all
x1 in1 mid1 inv
x2 mid1 out1 inv
.subckt inv in out
mn out in vss vss nch
mp vdd in out vdd pch
.ends
.end
(Output)
*** Leakage Current Result ***
Subckt Name=Top Level
Instance Name
Port
Max(A)
x1
in
.......
x1
out
.......
x2
in
.......
x2
out
.......
Total Power
.......
Subckt Name=inv
Instance Name
Port
Max(A)
mn
d
.......
mn
g
.......
mn
s
.......
mn
b
.......
mp
d
.......
mp
g
.......
mp
s
.......
mp
b
.......
Total Power
.......
HSPICE® User Guide: RF Analysis
E-2010.12
Min(A)
Avg(A)
Min(A)
Avg(A)
341
Chapter 14: Advanced Features
POWER Analysis
POWER Analysis
The .POWER statement in HSPICE RF creates a table, which by default
contains the measurements for AVG, RMS, MAX, and MIN for every signal
specified. For example,
.POWER signals [REF=vname FROM=start_time TO=end_time]
By default, the scope of these measurements are set from 0 to the maximum
timepoint specified in the .TRAN statement.
For syntax and description of .POWER statement, see .POWER in the HSPICE
and HSPICE RF Command Reference.
Example 1
In this example, no simulation start and stop time is specified for the x1.in
signal, so the simulation scope for this signal runs from the start (0ps) to the
last .tran time (100ps).
.power x1.in
.tran 4ps 100ps
Example 2
You can use the FROM and TO times to specify a separate measurement start
and stop time for each signal. In this example:
■
The scope for simulating the x2.in signal is from 20ps to 80ps.
■
The scope for simulating the x0.in signal is from 30ps to 70ps.
.param myendtime=80ps
.power x2.in REF=a123 from=20ps to=80ps
.power x0.in REF=abc from=30ps to=’myendtime - 10ps’
Setting Default Start and Stop Times
In addition to using FROM and TO times in a .POWER statement, you can also
use the SIM_POWERSTART and SIM_POWERSTOP options with .POWER
statements to specify default start and stop times for measuring signals during
simulation. These times apply to all signals that do not have their own defined
FROM and TO measurement times. For example,
.OPTION SIM_POWERSTART=time
.OPTION SIM_POWERSTOP=time
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Chapter 14: Advanced Features
Detecting and Reporting Surge Currents
These options control the power measurement scope; the default is for the
entire run.
For syntax and description of these options, see .OPTION
SIM_POWERSTART or .OPTION SIM_POWERSTOP in the HSPICE and
HSPICE RF Command Reference.
Controlling Power Analysis Waveform Dumps
You use the SIM_POWERPOST option to control power analysis waveform
dumping. For example,
.OPTION SIM_POWERPOST=ON|OFF
Considering the potentially enormous number of signals, there is no waveform
dumping by default for the signals in the .POWER statement. Setting
SIM_POWERPOST=ON turns on power analysis waveform dumping.
Detecting and Reporting Surge Currents
The .SURGE statement in HSPICE RF automatically detects and reports a
current surge that exceeds the specified surge tolerance. For example,
.SURGE surge_threshold surge_width node1 [node2 .... noden]
This statement reports any current surge that is greater than surge_threshold
for a duration of more than surge_width.
For additional information, see .SURGE in the HSPICE Reference Manual:
Commands and Control Options.
HSPICE® User Guide: RF Analysis
E-2010.12
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Chapter 14: Advanced Features
Detecting and Reporting Surge Currents
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HSPICE® User Guide: RF Analysis
E-2010.12
Index
A
accuracy control 314
algorithm
linear acceleration 308
nonlinear perturbation 167
numerical integration 313, 315
periodic AC 167
amplifier 20, 25
amplifier, IP3 29
amplitude modulation (AM) 173
AM-PM separation 173
analysis
phase noise 161
time domain steady-state 131
autocorrelation function 235
autocorrelation function, jitter measurement 247
B
Backward-Euler
algorithm 313, 315
integration 313, 315
block elements 71
broadband phasenoise 168
broadband phasenoise algorithm 168
C
.CHECK EDGE statement 338
.CHECK FALL statement 338
.CHECK GLOBAL_LEVEL statement 336
.CHECK HOLD statement 338
.CHECK IRDROP statement 340
.CHECK RISE statement 337
.CHECK SETUP statement 338
.CHECK SLEW statement 337
choke elements 71
circuit description syntax 14
clock source, random jitter 102
CMOS GPS VCO 41
Colpitts oscillator 37
.command
.PRINT ENV 273
command
.PROBE ENV 273
commands
hspicerf 13
PTDNOISE 218
comparing results 53
config file
hspicerf 323
configuration file 323
example 326
configuration options
flush_waveform 324
ground_floating_ node 324
hier_delimiter 324
html 324
integer_node 324
max_waveform_size 325
negative_td 325
port_element_ voltage_ matchload 325
rcxt_divider 325
unit_atto 326
v_supply 326
wildcard_left_range 326
wildcard_match_all 326
wildcard_match_one 326
wildcard_right_range 326
Custom WaveView 16
D
DC block elements 71
demo files
67
demo files, RF 67
demonstration files, RF 67
demonstration input files 67
Detailed Standard Parasitic Format See DSPF
device model cards 33
DSPF
expansion 288
file structure 282
345
Index
E
E
H
edge condition 338
element parameters
linear inductors 70
.ENV statement 270
Envelope Analysis (ENV) 269
envelope simulation 269
.ENVFFT 272
.ENVFFT statement 272
.ENVOSC 271
.ENVOSC statement 271
ergodic simulations 238
example
configuration file 326
examples, RF tutorials 19
Extended output variables 329
Harmonic Balance (HB) 107
analysis spectrum 111
equations 109
errors 128
options 113
oscillator analysis 144
output 116
syntax 110
warnings 128
.HB
for HBLIN 258
HB analysis
IP3 amplifier 29
power amplifier 25
HB_GIBBS option 122
HBAC 52, 189
errors 194, 199, 252
example 52
output 191, 273
output data files 193
syntax 191
warnings 194, 199, 252
HBAC analysis
mixer 50
.HBLIN 256, 259
limitations 257
output syntax 262
.HBLSP 263
example 266
input syntax 265
limitations 264
output data files 263, 268
output syntax 267
.HBOSC
options 152
HBOSC analysis
Colpitts oscillator 37
VCO 41
.HBOSC statement 143
HBXF
command 226
hier_delimiter configuration option 324
.hl# file 263
hold time verification 338
hspicerf command 13
hspicerf file 323
F
fall time
verification 338
files
.hl# 263
hspicerf 323
.ls# 268
.p2d# 268
.printhl# 263
.printls# 268
.printss# 268
.ss# 268
files, output 14
flags 323
flush_waveform configuration option 324
format
output
DSPF 281
format, output
NW 318
WDB 318
Foster pole-residue form
E element 91
G element 91
frequency-dependent noise sorces, modeling 238
G
generating output 14
ground_floating_ node configuration option 324
346
Index
I
hspicerf test 324
html configuration option 324
I
ideal transformer 70
inductors
node names 70
input files demonstration 67
input files, demo examples 67
integer_node configuration option 324
invoking HSPICE RF 13
IR drop
checking 340
J
jitter
random, with clock source 102
jitter measurements, transient noise 247
jitter, random, clock source 102
L
large-signal S parameter extraction 263
LIN analysis 20
linear
acceleration 307
matrix reduction 307
linear elements
elements, linear 72
low noise amplifier 20
.LPRINT statement 319
.ls# file 268
M
max_waveform_size configuration option 325
.measure 274
.MEASURE ENV command 274
mixer 50
model cards 33
Monte Carlo, TRANNOISE method 235
multi-tone HB analysis
mixer 50
N
negative_td configuration option 325
noise
.HBNOISE 201, 209
noise parameter extraction
small-signal 263
nonlinear perturbation algorithm 167
numerical integration 313, 315
NW output format 318
O
optimization 332
syntax 332
.OPTION
MAXORD 315
PURETP 316
SIM_ACCURACY 314
SIM_DELTAI 321
SIM_DELTAV 320
SIM_DSPF 280
SIM_DSPF_ACTIVE 280, 284
SIM_DSPF_INSERROR 286
SIM_DSPF_LUMPCAPS 286
SIM_DSPF_MAX_ITER 285
SIM_DSPF_RAIL 286
SIM_DSPF_SCALEC 286
SIM_DSPF_SCALER 286
SIM_DSPF_VTOL 285
SIM_LA 281, 307, 309
SIM_LA_FREQ 309
SIM_LA_MAXR 310
SIM_LA_MINC 310
SIM_LA_MINMODE 310
SIM_LA_TIME 310
SIM_LA_TOL 310
SIM_ORDER 313, 316
SIM_OSC_DETECT_TOL 316
SIM_POSTAT 328
SIM_POSTDOWN 329
SIM_POSTSCOPE 329
SIM_POSTSKIP 328
SIM_POWERDC_ACCURACY 340
SIM_POWERDC_HSPICE 340
SIM_POWERPOST 343
SIM_POWERSTART 342
SIM_SPEF 280
SIM_SPEF_ACTIVE 284
SIM_SPEF_INSERROR 286
SIM_SPEF_LUMPCAPS 286
SIM_SPEF_MAX_ITER 285
347
Index
P
SIM_SPEF_PARVALUE 287
SIM_SPEF_RAIL 286
SIM_SPEF_SCALEC 286
SIM_SPEF_SCALER 286
SIM_SPEF_VTOL 285
SIM_TG_THETA 316
SIM_TRAP 316
.OPTION HB_GIBBS 122
options, configuration file 324
oscillator
HB analysis 144
phase noise 161
oscillator example 37
output
files 14
format
DSPF 289
NW 318
tabulated data 317
WDB 318
generating 14
restricting 327
PTDNOISE
input syntax 220
.MEASURE 223
output file format 222
output syntax 222
overview 218
syntax 220
PTDNOISE command 218
P
S
.p2d# file 268
periodic AC algorithm 167
periodic pime-dependent noise analysis 218
phase modulation (PM) 173
phase noise 161
phase noise analysis 161
PHASENOISE 161, 164
PHASENOISE algorithms 167
PI (linear acceleration) algorithm 309
PLL, jitter measurements 177
port_element_voltage_matchload configuration
option 325
power amplifier 25
power amplifier IP3 29
.POWER statement 342
.POWERDC statement 340
.PRINT ENV command 273
.printhl# file 263
.printls# file 268
.printss# file 268
.PROBE command 273
Probing Subcircuit currents 329
S parameter extraction
large-signal 263
power-dependent 255
small-signal 263
SDE 235, 241
separating AM-PM noise 173
SETUP time verification 338
Shooting Newton
driven phase frequency circuit example 55
overview 131
ring oscillator example 62
SIM_ACCURACY option 314
SIM_ACTIVE option 280, 284, 285, 286, 287
SIM_DELTAI option 321
SIM_DELTAV option 320
SIM_DSPF option 280, 281, 313, 314, 320
SIM_DSPF_ACTIVE option 280, 284
SIM_DSPF_INSERROR option 286
SIM_DSPF_LUMPCAPS option 286
SIM_DSPF_MAX_ITER option 285
SIM_DSPF_RAIL option 286
SIM_DSPF_SCALEC option 286
SIM_DSPF_SCALER option 286
348
R
rcxt_divider configuration option 325
restricting output 327
results 53
reusing simulation output 319, 340, 342
RF
demo files 67
tutorial examples 19
RFdemo files 67
rise time
example 337
verify 337
Index
T
SIM_DSPF_VTOL option 285
SIM_LA option 281, 307, 309
SIM_LA_FREQ option 309
SIM_LA_MAXR option 310
SIM_LA_MINC option 310
SIM_LA_MINMODE option 310
SIM_LA_TIME option 310
SIM_LA_TOL option 310
SIM_ORDER option 313
SIM_POSTAT option 328
SIM_POSTDOWN option 329
SIM_POSTSCOPE option 329
SIM_POSTSKIP option 328
SIM_POWERDC_ACCURACY option 340
SIM_POWERED_HSPICE option 340
SIM_POWERPOST option 343
SIM_POWERSTART option 342
SIM_SPEF option 280
SIM_SPEF_ACTIVE option 284
SIM_SPEF_INSERROR option 286
SIM_SPEF_LUMPCAPS option 286
SIM_SPEF_MAX_ITER option 285
SIM_SPEF_PARVALUE option 287
SIM_SPEF_RAIL option 286
SIM_SPEF_SCALEC option 286
SIM_SPEF_SCALER option 286
SIM_SPEF_VTOL option 285
simulation engine 2
skip_nrd_nrs configuration option
configuration options
skip_nrd_nrs 325
slew rate
example 337
verification 337
small-signal noise parameter extraction 263
small-signal S parameter extraction 263
SN steady-state time domain analysis 131
SNAC
input syntax 195
output data files 198
SNFT 137
SNNOISE 209
input syntax 211
output data files 215
SNOSC 158
SNXF 230
spur (spurious) signals 163
.ss# file 268
starting
hspicerf 13
statement 271, 272
.ENV 270
.HBOSC 143
statements
.CHECK EDGE 338
.CHECK FALL 338
.CHECK GLOBAL_LEVEL 336
.CHECK HOLD 338
.CHECK IRDROP 340
.CHECK RISE 337
.CHECK SETUP 338
.CHECK SLEW 337
.HBXF 226
.LPRINT 319
.POWER 342
.POWERDC 340
.PTDNOISE 218
.SURGE 343
.TRAN 342
steady state time domain analysis, Shooting
Newton 131
Stochastic Differential Equation, TRANNOISE
method 235
strobejitter 223
subcircuit
probing currents 329
.SURGE statement 343
T
tabulated data output 317
TIE 235
TIE, jitter mreasurement 247
time domain steady state analysis 131
time interval error (TIE) 235
.TRAN statement 342
TRANNOISE
jitter measurements 235
Monte Carlo method 239
SDE method 241
transformer, ideal 70
transient noise jitter measurements 247
Trapezoidal (TRAP) integration algorithm 313, 315
tutorial 19
349
Index
U
overview 2
simulation engine 2
two-tone HB 51
V element 94
Verilog-A support 6
VMRF, See vector-modulated RF 92
U
W
unit_atto configuration option 326
waveform viewing 16
WaveView 16
WDB format 318
wildcard uses 327
wildcard_left_range configuration option 326
wildcard_match_all configuration option 326
wildcard_match_one configuration option 326
wildcard_right_range configuration option 326
V
v_supply configuration option 326
VCD format 318
VCO 41
vector-modualted RF 92
vector-modulated RF
E element 98
F element 98
G element 98
H element 98
I element 94
implementation 92
350
X
X() variable 329
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