Agilent N8201A Option 226 Performance Downconverter Synthetic

Agilent
N8201A Option 226
Performance Downconverter
Synthetic Instrument Module
3 Hz to 26.5 GHz
Technical Overview
and Self-Guided Tour for the Phase Noise
Measurement Personality
The phase noise measurement
personality on the Agilent
Technologies N8201A Option 226
performance downconverter
synthetic instrument module
provides advanced and comprehensive RF and microwave
measurement capability. You can
add the phase noise measurement
personality to transform the
N8201A into a one-button phase
noise tester. Whether you’re
in R&D or manufacturing, the
N8201A Option 226 phase
noise personality provides a
comprehensive measurement
solution to characterize the phase
noise behavior of your systems
and components easily, quickly,
and accurately.
Phase Noise Measurements Made Easier, Faster, and More Accurate
High-purity, high-stability signals
have become more important to the
modern communications, aerospace, and
defense industries. Phase noise is one of
the most crucial measures to evaluate the
short-term stability of a signal. Therefore,
an accurate, fast, and easy-to-use phase
noise measurement tool is critical in the
R&D and manufacturing environments.
In addition to its superior combination of
speed, accuracy, flexibility, and dynamic
range, the N8201A offers a Phase Noise
Measurement Personality - providing
an ideal tool for design verification and
troubleshooting, as well as production-line
testing. By adding this measurement
personality, you integrate a phase noise
tester and a high-performance spectrum
analyzer into one box.
• Expand design possibilities with
powerful measurement capability
and flexibility.
• Expedite troubleshooting and design
verification with an intuitive user
interface and numerous features.
• Streamline manufacturing with speed,
reliability, and ease of use.
• Maximize yields with accurate
measurements and operator
independent results.
This technical overview includes
• measurement details
• demonstrations
• N8201A key specifications
• ordering information
• related literature
All demonstrations utilize the N8201A and
the E4438C ESG vector signal generator.
Keystrokes surrounded by [ ] indicate hard
keys located on the soft front panel GUI,
and key names surrounded by { } indicate
menu keys located on the right edge of
the display.
Phase noise
log plot
page 3
Phase noise
cancellation
page 9
Spot frequency
phase noise
page 6
Integrated noise
page 10
DANL
measurements
page 8
2
Demonstration preparation
Begin by connecting the 50 Ω RF output
of the ESG vector signal generator to
the 50 Ω RF input of the N8201A with
a 50 Ω RF cable. Turn on the power in
both instruments.
Start the Agilent N8201A Option H02
Spectrum Analyzer GUI.
(Start > All Programs > Agilent SI
Tools > N8201A Option H02 Spectrum
Analyzer GUI.)
This exercise demonstrates how to set
up the ESG to provide an RF test signal.
If you do not have an ESG available,
you can turn on the N8201A’s internal
RF reference signal (50 MHz) to run
the following demonstration. Since
the N8201A’s center frequency
defaults to 50 MHz, you do not need
to change the center frequency of the
N8201A as shown in next section.
Product type
Model number
ESG vector signal generator
E4438C
Performance downconverter
N8201A
Instructions
Required options
Option 226 – phase noise
measurement personality
Keystrokes
On the ESG:
Set carrier frequency to 1 GHz.
[Preset] [Frequency] {1 GHz} and Enter
from the keyboard
Set amplitude to 0 dBm.
[Amplitude] {0 dBm} and Enter from the keyboard
Turn on RF output.
[RF On/Off]
Instructions
Keystrokes
If no source is available:
Turn on the N8201A’s internal 50 MHz RF
reference signal.
[Preset] [Mode] {Phase Noise} [Input/Output]
{Input/Output} {Input Port} {Amptd Ref}
Instructions
Keystrokes
Enter phase noise measurement mode.
[Preset] [Mode] {Phase Noise}
Set center frequency to 1 GHz.
[FREQUENCY] {1 GHz} and Enter
from the keyboard
Phase noise log plot
Log plot measures single-sideband phase
noise (in dBc/Hz) versus offset frequencies
expressed in logarithmic scale. This allows
you to view the phase noise behavior of
the signal under test across decades of
offset frequencies.
• View entire phase noise behavior
across a wide range of offset
frequencies (10 Hz to 100 MHz).
• Simultaneously display up to seven
decades of offset frequency in
logarithmic scale.
• Measure phase noise with a
user-specified number of averages.
• Perform trace smoothing with
user-adjustable smoothing
segment length.
• Utilize a suite of comprehensive
N8201A marker functions.
• Search carrier frequency automatically.
• Apply multilevel video filtering.
• Make single and continuous
measurements.
Activate log plot measurement.
[MEASURE] {Log Plot}
Observe the phase noise curve in a default setting.
Examine settings (Figure 1).
Use this step to make setup changes in any
measurement.
Figure 1.
Phase noise
log plot
This exercise demonstrates the
one-button phase noise log plot
measurement.
3
{Meas Setup}
These exercises demonstrate the
N8201A’s flexibility that enables
you to optimize your phase noise
measurements.
Note:
Averaging and video filtering are part of the
measurement. Therefore, every time you change
the number of averages and/or level of video
filtering, you need to restart the measurement to
obtain the results. Smoothing, on the other hand,
is a post-processing operation on the stored data.
You can observe the smoothed results while you
are changing the length of the smoothing segment.
Implementations of video filtering and smoothing
are fast, whereas averaging takes longer.
Span and amplitude
Instructions
Keystrokes
Specify the span of offset frequencies:
Set start offset frequency to 100 Hz.
[SPAN] {Start Offset} {100 Hz} and Enter from
the keyboard
Set stop offset frequency to 100 MHz.
{Stop Offset} {100 MHz} and Enter from
the keyboard
Specify amplitude scale:
Set reference value to –85 dBc/Hz.
[AMPLITUDE] {Ref Value} {–85 dBc/Hz} and
Enter from the keyboard
Set scale per division to 7 dB.
{Scale/Div} {7 dB} and Enter from the keyboard
Restart the measurement.
[Restart]
Averaging, video filtering and smoothing
Instructions
Keystrokes
Activate averaging and set average number to 5.
[Meas Setup] {Avg Number} until “On” is
underlined, then {5} and Enter from the keyboard
Restart the measurement (Figure 2).
Observe convergence of the raw data trace.
[Restart]
Disable averaging.
Press {Avg Number} until “Off” is underlined
Activate video filtering and set filtering level to
“Maximum”.
{Filtering} {Maximum}
Restart the measurement.
Observe the filtering result (Figure 3).
[Restart]
View smoothed data trace with raw or averaged
trace turned off.
[Trace/View], press {Trace} until “1” is
underlined, {Blank}
Adjust length of smoothing segment.
Observe the displayed traces with different
smoothing segments (Figure 4).
[Meas Setup] {Smoothing}, then press [⇓] or [⇑],
or rotate the knob
Figure 2.
Phase noise plot
with averaging
4
Figure 3.
Phase noise plot
with video filtering
Figure 4.
Smoothed
phase noise plot
5
Spot frequency phase noise
If you are interested in phase noise versus
time at a single offset frequency, use the
spot frequency phase noise measurement.
• Monitor phase noise fluctuation
versus time at a user-specified
single offset frequency (between
100 Hz and 100 MHz).
• Use the N8201A’s phase noise
optimization feature to minimize the
downconverter’s internal phase noise.
• Check carrier frequency drifting
with carrier signal tracking.
• Search carrier frequency
automatically.
• View results in graphic and
numeric list formats.
In this exercise, you will measure the
spot frequency at 20 kHz and explore
the signal tracking and the carrier
frequency drifting features.
Instructions
Keystrokes
Activate the spot frequency measurement.
[MEASURE] {Spot Frequency}
Specify the spot frequency to 20 kHz.
[Meas Setup] {Spot Offset} {20 kHz} and Enter
on the keyboard
Adjust amplitude scale to optimize the display.
Observe the real-time phase noise display
at 20 kHz offset frequency (Figure 5).
[Amplitude] {Phase Noise} {Ref Value}
{–110 dBc/Hz} and Enter on the keyboard
{Scale/Div} {0.5 dB} and Enter from the
keyboard, then rotate the knob for fine
adjustment with either {Ref Value}
or {Scale/Div} pressed
View spot frequency phase noise with a table of
numerical readouts.
[Trace/View] {Numerical}
Return to graphical view.
{Graphical}
Turn on signal tracking to check carrier frequency
drift. Check the carrier frequency drifting at a
fixed time interval, for example at each 10 percent
of one sweeping cycle.
[Frequency], toggle {Signal Track} to “On”
{Tracking} {Mode} {Interval} {Interval}
{10} and Enter on the keyboard
Adjust amplitude scale of frequency drifting
(or Delta Frequency).
Observe the spot frequency phase noise with
carrier drifting plot (Figure 6).
[Amplitude] {Delta Freq}, {Scale/Div}, then
rotate the knob to an optimized display
Check the frequency stability of the carrier signal
when the carrier drifting goes beyond the
specified tolerance. This example uses a
±1 dBc/Hz tolerance level.
[Frequency], toggle {Signal Track} to “On”,
{Tracking} {Mode} {Tolerance} {Tolerance ±}
{1 dBc/Hz} and Enter on the keyboard
Set amplitude scale of frequency drifting (or
delta frequency) to 1 kHz/Div.
[Amplitude] {Delta Freq} {Scale/Div} {1 kHz}
and Enter on the keyboard
Check frequency drifting at the “Delta Freq”
panel while manually adjusting the ESG RF
output frequency by ±2 kHz increments.
Set ESG: [Frequency], then rotate the knob
clock- or counterclock-wise around the
previously specified center frequency
6
Figure 5.
Spot frequency
phase noise
Figure 6.
Phase noise with
carrier drifting
7
Displayed average noise level
(DANL) measurements
The DANL floor of a spectrum analyzer sets
limitations for measuring the smallest in
put signal, usually at the far-out offset
frequencies. When the amplitude of a
signal under test is getting closer to the
DANL floor, a significant measurement
error can occur, which makes the
measurement no longer valid. To help
you ensure the measurement is valid,
the N8201A with the phase noise
measurement personality measures
the DANL floor and displays it along with
the phase noise plot. It also automatically
optimizes the N8201A input attenuation
level for the far-out offset frequency
to lower the DANL floor for a better
measurement sensitivity.
• Measure and reference the DANL
of the N8201A to the carrier amplitude.
• Display the DANL floor together
with the log plot phase noise.
• Store and record traces easily.
Instructions
Keystrokes
Re-enter phase noise measurement mode
in the N8201A.
[Preset] [Mode] {Phase Noise}
Set center frequency to 1 GHz.
[FREQUENCY] {1 GHz} and Enter on the keyboard
Activate log plot measurement.
[MEASURE] {Log Plot}
Adjust the X-scale.
[SPAN] {Start Offset} {1 kHz} and Enter on
the keyboard {Stop Offset} {100 MHz} and
Enter on the keyboard
Adjust the Y-scale.
[AMPLITUDE] {Ref Value} {–85 dBc/Hz} and
Enter on the keyboard
View the smoothed phase noise plot without
raw data.
[Trace/View], toggle {Trace} to underline “1”,
{Blank}
Transfer the smoothed phase noise curve from
“Trace 2” to “Trace 3”.
Toggle {Trace} to underline “2”, {More 1 of 2}
{Operations} {2 → 1}.
Activate the DANL measurement.
Note the stepped DANL floor that results from
the DANL optimization (Figure 7, lower trace).
[Meas Setup] {Meas Type} {DANL Floor}
[Restart]
Figure 7.
DANL floor displayed
with a smoothed
phase noise plot
The following exercise demonstrates
the DANL measurements, display, and
optimization.
8
There are two ways to measure the DANL
floor. One way is to remove the signal from
the N8201A and terminate the RF input of
the N8201A with a 50 Ω termination. The
other way is to suppress the input signal
to a negligible level at the input mixer by
increasing the input attenuation to 70 dB.
While the measurement personality
defaults to the latter, you can also choose
to physically remove the signal from the
N8201A RF input and terminate it as
follows.
Instructions
Keystrokes
Set DANL measurement method as “Removal”.
[Input/Output], toggle {DANL Method} to
underline “Removal”
Activate the DANL measurement.
[Restart], then you will see an instruction panel,
follow the instructions to remove the signal
from the N8201A input and to connect a 50 Ω
termination at the RF input. Press [ESC] to
continue.
Phase noise cancellation
The N8201A also features phase noise
cancellation. Using a source with low
phase noise, you can eliminate the
influence of the N8201A’s internal phase
noise on measurement results for close-in
offset frequencies.
•
•
Improve measurement accuracy
and sensitivity.
Make the best trade-off between
cancellation effectiveness and
computation time with userselectable thresholds.
9
Integrated noise
Different applications require different
measures for evaluating phase noise
behaviors. In the digital world, root-meansquare (rms) phase deviation/jitter (in
degrees or radians) and rms phase jitter
(in seconds) are used more frequently to
evaluate the stability of a high-frequency
clock. On the other hand, the residual FM
is more important to amplifier designers
and manufacturers. With the N8201A,
these measures can be calculated by
positioning a pair of markers to specify
the interval of integration.
• Characterize phase noise related
behaviors from different angles for
various applications.
• Adjust integration bandwidth by
positioning a pair of markers on the
log plot.
• Calculate rms phase deviation/jitter
in degrees or radians.
• Calculate rms phase jitter in seconds.
• Calculate the residual FM in Hz.
• View numeric marker readings for
calculated results.
With the phase noise plot obtained in
the previous demonstration, use the
markers to make the integrated noise
measurements.
Instructions
Keystrokes
Clear the DANL floor from the results obtained
in the previous demonstration.
[Trace/View], toggle {Trace} to underline “2”,
{Blank}
Set the starting point of the integration interval
to 10 kHz.
Notice a marker labeled “1” shows up on the
phase noise plot at 10 kHz offset frequency.
[Marker] {More}, toggle {Marker Trace} until
“1” is underlined, {More} {Normal} {10 kHz}
and Enter on the keyboard
Activate the rms phase deviation (in degrees)
measurement.
Notice a marker labeled “1R” superimposed
on the marker labeled “1”.
{RMS Noise} {RMS Noise Degree}
Set the ending point of the integration interval
to 1 MHz.
The rms phase deviation/jitter in degrees
between 10 kHz and 1 MHz is shown in the top
right corner of the display (Figure 8).
{1 MHz} and Enter on the keyboard
Change the rms phase deviation/jitter into
radians. Notice the readout in the top right
corner changes to radians.
{RMS Noise Radian}
Change the rms phase jitter into seconds.
Notice the readout in the top right corner
changes to seconds.
{RMS Noise Jitter}
For residual FM, set the integration interval
starting from 30 kHz. Notice a marker labeled
“1” shows up on the phase noise plot at
30 kHz offset frequency.
[Marker] {Normal} {30 kHz} and Enter on
the keyboard
Activate the residual FM measurement, and
set the integration interval ending at 1 MHz.
The top right corner of the display shows the
integration interval and the residual FM in Hz
(Figure 9).
{Residual FM} {1 MHz} and Enter on
the keyboard
.
10
Figure 8.
RMS phase
deviation in degrees
Figure 9.
Residual FM
11
N8201A Option 226
Key Specifications1
Phase noise measurement personality
Measurement modes
Spectrum monitor
Log plot
Spot frequency
Offset frequency range
Minimum offset frequency
Maximum offset frequency
Spot frequency measurement
Log plot measurement
100 MHz
Up to 10 GHz
Maximum number of decades
7
Maximum input signal level
+20 dBm
Minimum input signal level
(for optimum dynamic range)
–50 dBm
Measurement accuracy (nominal)
Amplitude accuracy
Amplitude repeatability
10 Hz
±0.29 dB (RSS of error sources, each of
which is warranted, not including repeatabilty)
±0.34 dB rms (example standard deviation at
10 kHz offset, 4% smoothing, medium video filtering.
Can be reduced with more smoothing, filtering
and averaging)
Video filtering
Four levels:
None (VBW/RBW = 1.0)
Little (VBW/RBW = 0.3)
Medium (VBW/RBW = 0.1)
Maximum (VBW/RBW = 0.03)
Smoothing
Fine-adjustable between 0% and 16%
rms noise calculation
rms phase deviation, rms phase jitter,
and residual FM are calculated over a
user-specified integration interval
System phase noise
See Figures 10 and 11.
Figure 11. Nominal phase noise at different carrier frequencies (CFs)
Figure 10. Nominal phase noise of different LO optimizations
1. See the N8201A performance downconverter synthetic instrument module data sheet for more
specification details (literature number 5989-5720EN).
12
References
Web resources
For additional information on synthetic instruments, visit:
www.agilent.com/find/synthetic
For additional information on instrument security issues, visit:
www.agilent.com/find/security
For information about renting, leasing, or financing Agilent’s latest technology, visit:
www.agilent.com/find/buy/alternatives
For additional accessory information, visit:
www.agilent.com/find/accessories
For additional information about Agilent PSA Series spectrum analyzers, visit:
www.agilent.com/find/psa
Related literature
Synthetic instruments
N8201A Performance Downconverter Synthetic Instrument Module, 3 Hz to 26.5 GHz, Data Sheet
Literature number 5989-5720EN
N8201A Option 219 Performance Downconverter Synthetic Instrument Module 3 Hz to 26.5 GHz, Technical Overview
and Self-Guided Tour for the Noise Figure Measurement Personality
Literature number 5989-6747EN
N8201A Option 226 Performance Downconverter Synthetic Instrument Module 3 Hz to 26.5 GHz, Technical Overview
and Self-Guided Tour for the Phase Noise Measurement Personality
Literature number 5989-6748EN
N8201A Option V7L Performance Downconverter Synthetic Instrument Module 3 Hz to 26.5 GHz, Technical Overview
and Self-Guided Tour for the Fast Rise Time Video Output
Literature number 5989-6749EN
N8211A Performance Analog Upconverter Synthetic Instrument Module, 250 kHz to 20/40 GHz, Data Sheet
Literature number 5989-2592EN
N8212A Performance Vector Upconverter Synthetic Instrument Module, 250 kHz to 20 GHz, Data Sheet
Literature number 5989-2593EN
N8221A IF Digitizer Synthetic Instrument Module, 30 MS/s, Data Sheet
Literature number 5989-2594EN
N8241A Arbitrary Waveform Generator Synthetic Instrument Module, 15-Bit, 1.25 GS/s or 625 MS/s, Technical Overview
Literature number 5989-2595EN
N8242A Arbitrary Waveform Generator Synthetic Instrument Module, 10-Bit, 1.25 GS/s or 625 MS/s, Technical Overview
Literature number 5989-5010EN
N8201A-H02 Compact Performance Spectrum Analyzer for ATE Applications,
Literature number 5989-5721EN
Spectrum analyzer literature
PSA Series High-Performance Spectrum Analyzer, Brochure
Literature number 5980-1283E
Agilent PSA Series Spectrum Analyzers, Data Sheet
Literature number 5980-1284E
13
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Revised: May 7, 2007
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© Agilent Technologies, Inc. 2007
Printed in USA, June 29, 2007
5989-6748EN