Mixer Application Note PDF

Mixer Application Note PDF
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v01.05.00
HMC141/142 MIXER OPERATION NOTE
RF & LO Port Designations for the HMC141 and HMC142 Double-Balanced Mixers
Although the mixers operate acceptably when RF & LO ports are interchanged, use the following guidelines
for best performance.
Downconverter Operation
Use the Datasheet Outline Drawing (DOD) to determine port designation for typical downconverter performance per the HMC141/142 data sheet.
• Apply RF Input to RF Port so labelled on DOD and on MMIC die.
• Apply LO Input to LO Port so labelled on DOD and on MMIC die.
• Access IF Output at IF Port so labelled on DOD and on MMIC die.
Upconverter Operation
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17 - 112
Reverse the port designation specified by the Datasheet Outline Drawing (DOD) for typical upconverter
performance per the HMC141/142 data sheet on page 4-14.
• Apply IF Input to IF Port so labelled on DOD and on MMIC die.
• Apply LO Input to RF Port so labelled on DOD and on MMIC die.
• Access RF Output at LO Port so labelled on DOD and on MMIC die.
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v01.05.00
HMC143/144 MIXER OPERATION NOTE
RF & LO Port Designations for the HMC143 and HMC144 Double-Balanced Mixers
Although the mixers operate acceptably when RF & LO ports are interchanged, use the following guidelines
for best performance:
Upconverter & Downconverter Operation
The RF & LO port markings on the MMIC die are correct and are consistent with the connection designated
in the Datasheet Outline Drawing (DOD) found on the HMC143/144 data sheet.
Use the Datasheet Outline Drawing (DOD) to determine port designation for typical performance per data
sheet.
Use the same port designations for both upconverter & downconverter operation.
For Example, in Downconverter Operation:
• Apply RF Input to RF Port so labelled on DOD and labelled “RF” on the MMIC die.
17
• Access IF Output at IF Port so labelled on DOD and on MMIC die.
For Example, in Upconverter Operation:
• Apply IF Input to IF Port so labelled on DOD and on MMIC die.
• Apply LO Input to LO Port so labelled on DOD and labelled “LO” on the MMIC die.
• Access RF Output at RF Port so labelled on DOD and labelled “RF” on the MMIC die.
For price, delivery, and to place orders, please contact Hittite Microwave Corporation:
20 Alpha Road Chelmsford, MA 01824 Phone: 978-250-3343 Fax: 978-250-3373
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PRODUCT APPLICATION NOTES
• Apply LO Input to LO Port so labelled on DOD and labelled “LO” on the MMIC die.
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v00.1203
HIGH IP3 MIXERS FOR
CELLULAR APPLICATIONS
Introduction
The explosive growth in the Cellular market over the last few years has created a demand for ever smaller
infrastructure equipment to be used for in-building applications and other space limited installations, where the
traditional large multiple rack base station is not feasible. The infrastructure equipment consists of digital call
processing and an analog transmitter/receiver section. The RF section of a typical cellular transceiver is shown
in figure 1.
Figure 1 – Transceiver block diagram
PRODUCT APPLICATION NOTES
17
Cellular communications employ many different and complex modulation schemes to transmit voice and data.
Table 1 lists the characteristics of several popular cellular standards. These standards employ modulation
methods that increase the peak to average power of the transmitted signal in proportion to the number of
channels being transmitted. This, in turn, requires the receiver to have high linearity to minimize distortion of
the channel.
Communications
Standard
Mobile
Frequency (MHz)
Channel
Bandwidth (MHz)
Modulation
Scheme
Peak to Average
Power Ratio
CDMA
Rx: 460 - 468
869 - 894
1930 - 1990
2110 - 2170
Tx: 450 - 458
824 - 849
1850 - 1910
1920 - 1980
1.25
QPSK/OQPSK
9 to 10 dB
WCDMA
(FDD)
Rx: 2110 - 2170
Tx: 1920 - 1980
(TDD)
1900 - 1920
2010 - 2025
unpaired spectrum
5
QPSK
8 to 9 dB
GSM/EDGE
Rx: 460 - 468
488 - 496
869 - 894
925 - 960
1805 - 1880
1930 - 1990
Tx: 450 - 458
478 - 486
824 - 894
880 - 915
1710 - 1785
1850 - 1910
0.2
GMSK
8-PSK (EDGE only)
1 to 2 dB
TDMA
Rx: 869 - 894
1930 - 1990
Tx: 824 - 849
1850 - 1910
0.03
π /4 DQPSK
3 to 4 dB
Table 1 – Popular cellular phone standards
17 - 114
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v00.1203
HIGH IP3 MIXERS FOR
CELLULAR APPLICATIONS
Figure 2 shows the frequency spectrum of a single-carrier CDMA waveform. The main channel contains the
desired information to be transmitted or received. The “shoulders” of the spectrum are created by intermodulation
products generated within the main channel. Error Vector Magnitude (EVM) and Bit Error Rate (BER), which
are parameters commonly used to quantify the quality of the digital channel, are adversely affected by distortion
or interference in the main channel. Adjacent channels, which coincide in frequency with the “shoulders” of the
CDMA channel, will suffer interference due to the excess energy contained in the shoulders. Adjacent Channel
Power Ratio (ACPR) is a measure of the amount of power in the “shoulders” relative to the main channel power
and also serves as a measure of the linearity of the channel.
The major contributors to channel distortion in a cellular receiver are the front-end Low Noise Amplifier (LNA)
and mixer. This application note will discuss the performance requirements for high linearity mixers used in the
cellular receiver chain.
CMDA SPECTRUM
-10
-20
-30
-40
MAIN CHANNEL
-50
SHOULDERS
-60
SHOULDERS
17
-70
-90
148
148.5
149
149.5
150
150.5
151
151.5
152
FREQUENCY (MHz)
Figure 2 – CDMA channel frequency spectrum
Cellular Receiver Front End
In order to understand the significance of mixer performance parameters to the cellular receive chain, a system
level simulation of a receiver front end was performed using =SPECTRASYS=1. The system simulation allowed
us to see the effects of mixer nonlinearity, spurious performance and isolation simultaneously on the received
channel.
The schematic block diagram that was entered into the simulation software is shown in figure 3. The simulation
was created to show the effect of an interferer landing in the frequency band of interest, once the signals are
down converted in the receiver.
ANT
BPF
AMP
MIXER
R
L
I
IF output
LO port
PRODUCT APPLICATION NOTES
-80
Figure 3 – Receiver simulation schematic block diagram
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HIGH IP3 MIXERS FOR
CELLULAR APPLICATIONS
The mixer model used allowed us to enter a table containing the mixer spurious levels based on measured mixer
performance. The values for the table and the other performance parameters (see figure 4) were taken directly
from the datasheet of the HMC400MS8 mixer. Figure 5 shows the results of the simulation, as seen at the IF
output of the mixer. For this simulation, the RF input frequency was 1880 MHz, the LO frequency was 1780
MHz, and an interferer was at 1830 MHz (at the RF port of the mixer). The 2x2 spur, created by the LO and the
interferer, lands directly in the center of the received channel at 100 MHz. While not visible in the spectrum of
the channel spectrum itself, the spur does degrade EVM and BER.
PRODUCT APPLICATION NOTES
17
Figure 4 – =SPECTRASYS= mixer parameters
MIXER IF SPECTRUM
0
-10
-20
2X2 SPUR DUE TO INTERFERER
-30
-40
-50
-60
-70
98
98.5
99
99.5
100
100.5
101
101.5
102
FREQUENCY (MHz)
Figure 5 – Spur inside digital channel
17 - 116
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v00.1203
HIGH IP3 MIXERS FOR
CELLULAR APPLICATIONS
Selecting the Right Mixer
When selecting a high IP3 mixer, consideration must be given to other important parameters including LO drive
level, isolation and spurious performance. Hittite Microwave Corporation uses a single-ended topology for the
mixers with input IP3 >+30 dBm and a double-balanced approach for mixers with input IP3 in the +25 to +30
dBm range. Table 2 lists the family of high IP3 mixers from Hittite Microwave Corporation.
RF Frequency
(MHz)
IF Frequency
(MHz)
IP3
(dBm)
LO
(dBm)
Conversion
Gain (dB)
Type
of Mixer
HMC387MS8
300-500
DC-150
32
17
-9.5
sgl-end
HMC400MS8
1700-2200
DC-300
36
17
-9
sgl-end
HMC399MS8
740-960
DC-250
35
17
-8.5
sgl-end
HMC485MS8G
1700-2200
50-300
34
0
-9
sgl-end
HMC402MS8
1800-2200
DC-500
31
17
-8.5
sgl-end
HMC304MS8
1700-3000
DC-800
30
17
-9
sgl-bal
HMC350MS8
600-1200
DC-300
27
19
-7.5
dbl-bal
HMC351S8
700-1200
DC-300
26
19
-8
dbl-bal
HMC316MS8
1500-3500
DC-1000
25
17
-8
dbl-bal
HMC216MS8
1300-2500
DC-650
25
3-11
-9
dbl-bal
Table 2 – High IP3 mixers from Hittite Microwave
For applications where spurious and isolation performance is secondary to IP3, a single-ended mixer with the
highest IP3 performance is the best choice. For applications with critical spurious issues, a double-balanced
mixer with high IP3 performance is the best choice. This is often the case for a receiver that tunes over a wide
IF bandwidth, where narrow IF filters cannot be used.
Figure 6 contrasts the simulated IF output spectrum for a single-ended mixer and a double-balanced mixer.
For the simulation in figure 6, two tones separated by 10 MHz are injected into the RF port of the mixer and the
desired 100 MHz IF signal is viewed in the spectrum analyzer output. Figure 6(a) shows the performance of the
HMC400MS8 single-ended, high-IP3 mixer. This mixer has an input IP3 of approximately +35 dBm and 2x2
spurious suppression of -59 dBc. As expected, the excellent IP3 performance places the third-order products
near the noise floor, while the second order products are clearly visible and at their expected level.
In Figure 6(b), the double-balanced HMC316MS8 mixer, with an input IP3 of +25 dBm and 2x2 spurious
suppression of -77 dBc is shown. The tradeoff between input IP3 and spurious performance is clearly visible.
For price, delivery, and to place orders, please contact Hittite Microwave Corporation:
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17
PRODUCT APPLICATION NOTES
Part
Number
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HIGH IP3 MIXERS FOR
CELLULAR APPLICATIONS
HMC400MS8 IF OUTPUT SPECTRUM
-20
-40
3rd ORDER PRODUCTS
-60
2nd ORDER PRODUCTS
-80
-100
-120
0
50
100
150
200
250
300
350
400
IF FREQUENCY (MHz)
(a)
HMC316MS8 IF OUTPUT SPECTRUM
-20
PRODUCT APPLICATION NOTES
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-40
3rd ORDER PRODUCTS
-60
2nd ORDER PRODUCTS
-80
-100
-120
0
50
100
150
200
250
300
350
400
IF FREQUENCY (MHz)
(b)
Figure 6 – IF output spectrum for the (a) HMC400MS8 and (b) HMC316MS8 mixer
Measurements were performed to study the impact of IP3 and spurious performance on a CDMA channel. For a
CDMA signal, the 3rd order products create the “shoulders” of the channel response and directly impact ACPR.
Figure 7(a) shows the IF output of the HMC400MS8 mixer driven with a strong CDMA signal centered at 1.85
GHz with a channel power of +6 dBm. The ACPR was measured at -64 dBc at the IF output. In Figure 7(b), the
HMC316MS8 was driven by the same CDMA signal and the impact of the mixer IP3, in this case 10-dB lower
than the HMC400MS8, can be clearly seen in the lower ACPR.
For price, delivery, and to place orders, please contact Hittite Microwave Corporation:
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v00.1203
HIGH IP3 MIXERS FOR
CELLULAR APPLICATIONS
(a)
(b)
Figure 7 – CDMA output spectrum for the (a) HMC400MS8 and (b) HMC316MS8 mixer
For price, delivery, and to place orders, please contact Hittite Microwave Corporation:
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PRODUCT APPLICATION NOTES
17
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HIGH IP3 MIXERS FOR
CELLULAR APPLICATIONS
In order to observe the effects of spurious signals on the CDMA channel, a =SPECTRASYS= simulation was
performed in order to view the spurious signal inside the CDMA channel. In figure 8, the same two mixers are
compared for their 2x2 spurious responses. Comparing figure 8(a) and 8(b) the superior spurious performance
of the HMC316MS8 mixer is clearly reflected in the spurious response at 100 MHz.
MIXER WITH -49 dBc 2x2 SPUR
-10
-20
-30
2x2 SPUR
-40
-50
-60
-70
-80
98
98.5
99
99.5
100
100.5
101
101.5
102
FREQUENCY (MHz)
(a)
17
MIXER WITH -77 dBc 2x2 SPUR
PRODUCT APPLICATION NOTES
-10
17 - 120
-20
-30
-40
-50
2x2 SPUR
-60
-70
-80
98
98.5
99
99.5
100
100.5
101
101.5
102
FREQUENCY (MHz)
(b)
Figure 8 – Simulated spurious performance of the (a) HMC400MS8 and (b) HMC316MS8 mixer
In order to see the effect of the spurious signal on the CDMA channel, a measurement of EVM was made on
both mixers with the results shown in figure 9. For this measurement, an interferer centered at 2 GHz with +4
dBm power was injected into the RF port of the mixer along with the CDMA signal with -8.6 dBm channel power.
The interferer signal was toggled on and off in order to observe the effect on measured EVM. In figure 9(a), the
HMC316MS8 mixer EVM was measured at 3.4% with the interferer present and 3.4% with no interfering signal.
In figure 9(b), the HMC400MS8 mixer also has and EVM of 3.4% with no interferer, but a noticeable degradation
to 4.3% with the interferer present.
For price, delivery, and to place orders, please contact Hittite Microwave Corporation:
20 Alpha Road Chelmsford, MA 01824 Phone: 978-250-3343 Fax: 978-250-3373
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v00.1203
HIGH IP3 MIXERS FOR
CELLULAR APPLICATIONS
(a)
(b)
Figure 9 – Measured EVM performance of the (a) HMC316MS8 and (b) HMC400MS8 mixer
Conclusion
Increasing the linearity and dynamic range of a cellular receiver will lead to improved system performance,
measured by decreased BER and EVM. The dynamic range of the receiver is dependent upon the linearity of
the receiver front end which includes the mixer. The use of high IP3 mixers improves the ACPR, EVM, and BER
of the receiver. While the IP3 performance of the mixer is critical to the linearity of the receiver, good spurious
performance from the mixer is also important in maintaining the quality of the digital channel.
(Endnotes)
1
PRODUCT APPLICATION NOTES
17
=SPECTRASYS=, RF and Microwave Linear simulation software, Eagleware Corporation, Norcross, GA
For price, delivery, and to place orders, please contact Hittite Microwave Corporation:
20 Alpha Road Chelmsford, MA 01824 Phone: 978-250-3343 Fax: 978-250-3373
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17 - 121
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HIGH IP3 MIXERS FOR
CELLULAR APPLICATIONS
Notes:
PRODUCT APPLICATION NOTES
17
17 - 122
For price, delivery, and to place orders, please contact Hittite Microwave Corporation:
20 Alpha Road Chelmsford, MA 01824 Phone: 978-250-3343 Fax: 978-250-3373
Order Online at www.hittite.com
v00.1203
HIGH IP3 MIXERS FOR
CELLULAR APPLICATIONS
Notes:
PRODUCT APPLICATION NOTES
17
For price, delivery, and to place orders, please contact Hittite Microwave Corporation:
20 Alpha Road Chelmsford, MA 01824 Phone: 978-250-3343 Fax: 978-250-3373
Order Online at www.hittite.com
17 - 123
v00.1203
SUBHARMONIC vs. FUNDAMENTAL MIXERS
FOR HIGH CAPACITY MILLIMETERWAVE RADIOS
Introduction
The microwave and VSAT radio market in the past decade has significantly grown from primarily voice and data
communication to a mix of data, video, internet, and voice services. These newer standards require complex
digital modulation schemes which have higher bandwidth requirements, which in turn require higher transmit
frequencies. The point to point frequency spectrum ranges from 2.11 GHz to 42 GHz.
To meet the low cost and reliability requirements of these microwave radios Hittite Microwave Corporation
has designed integrated MMIC circuits that meet these new market demands. These new devices include
components such as mixers, VCOs, prescalers, attenuators and amplifiers to integrated down-converters, upconverters, frequency multipliers, phase-locked oscillators (PLOs) and multi-chip modules (MCMs). Figure 1
shows a block diagram of a typical microwave radio transmit and receive chain in a typical super-heterodyne
architecture.
PRODUCT APPLICATION NOTES
17
17 - 124
Figure 1 - Microwave super-heterodyne point-to-point radio
The transmit and receive chains both contain amplifiers and mixers which are realized as Microwave Monolithic
Integrated Circuits (MMIC). The amplifiers typically incorporate some type of automatic gain control to prevent
saturation of succeeding components, particularly the analog to digital converter. There are filters at the
transmit and receive frequency to reject interference and spurious products generated by the amplifiers and
mixers as well as out-of-band interferers. The mixers shown in figure 1 are comprised of both subharmonic and
fundamental mixers. The subharmonic mixers require a local oscillator (LO) signal which is at approximately ½
the RF frequency. These mixers create the majority of spurious signals present in the receiver and transmitter.
Since the levels of the spurious emissions will drive the complexity of the filters, a mixer with good spurious
performance and a carefully-designed frequency plan is required.
Hittite Microwave Corporation offers a variety of millimeter-wave subharmonic and balanced mixers that meet
the requirements for millimeter-wave radios. Hittite’s line of sub-harmonically pumped mixers range in frequency
from 14 – 42 GHz making them ideal for millimeter-wave radio applications. These mixers are available with an
integrated LO and IF amplifier in a SMT leadless chip carrier package as well as die. The excellent 2LO to RF
and IF isolation minimizes the transmit and receive filter requirements. The mixers with integrated LO and IF
amplifiers require only a single DC bias and -4 dBm of LO drive.
This product note will discuss and compare the use of a subharmonic mixer and double-balanced mixer in the
27 GHz millimeter-wave radio band.
Criteria for the Front-end Mixer
The subharmonic mixer is the primary front end mixer found in the majority of millimeter-wave radio designs.
What makes this mixer unique is that it operates with a LO frequency at ½ the RF frequency, therefore eliminating
the requirement for a more complex and costly high frequency LO. The subharmonic mixer also naturally rejects
even-order spurious emissions. A carefully designed mixer can achieve 2*LO isolation as high as 35 dB. Prior
For price, delivery, and to place orders, please contact Hittite Microwave Corporation:
20 Alpha Road Chelmsford, MA 01824 Phone: 978-250-3343 Fax: 978-250-3373
Order Online at www.hittite.com
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