a
APPLICATIONS
High Performance RF/IF Mixer
Direct to Baseband Conversion
Image-Reject Mixers
I/Q Modulators and Demodulators
PRODUCT DESCRIPTION
The AD831 is a low distortion, wide dynamic range, monolithic
mixer for use in such applications as RF to IF down conversion
in HF and VHF receivers, the second mixer in DMR base stations, direct-to-baseband conversion, quadrature modulation and demodulation, and doppler-shift detection in ultrasound imaging applications. The mixer includes an LO driver
and a low-noise output amplifier and provides both user-programmable power consumption and 3rd-order intercept point.
The AD831 provides a +24 dBm third-order intercept point for
–10 dBm LO power, thus improving system performance and
reducing system cost compared to passive mixers, by eliminating
the need for a high power LO driver and its attendant shielding
and isolation problems.
The RF, IF, and LO ports may be dc or ac coupled when the
mixer is operating from ± 5 V supplies or ac coupled when operating from a single supply of 9 V minimum. The mixer operates
with RF and LO inputs as high as 500 MHz.
The mixer’s IF output is available as either a differential current
output or a single-ended voltage output. The differential output
is from a pair of open collectors and may be ac coupled via a
transformer or capacitor to provide a 250 MHz output bandwidth. In down-conversion applications, a single capacitor connected across these outputs implements a low-pass filter to
reduce harmonics directly at the mixer core, simplifying output
AN
IFN
VP
IFP
AP
FUNCTIONAL BLOCK DIAGRAM
3
2
1
20
19
50Ω
50Ω
GND
4
18
COM
VN
5
17
VFB
RFP
6
16
OUT
RFN
7
15
VN
14
BIAS
10
11
12
VP
13
GND
9
LOP
8
LON
VN
AD831
VP
FEATURES
Doubly-Balanced Mixer
Low Distortion
+24 dBm Third Order Intercept (IP3)
+10 dBm 1 dB Compression Point
Low LO Drive Required: –10 dBm
Bandwidth
500 MHz RF and LO Input Bandwidths
250 MHz Differential Current IF Output
DC to >200 MHz Single-Ended Voltage IF Output
Single or Dual Supply Operation
DC Coupled Using Dual Supplies
All Ports May Be DC Coupled
No Lower Frequency Limit—Operation to DC
User-Programmable Power Consumption
Low Distortion Mixer
AD831
filtering. When building a quadrature-amplitude modulator or
image reject mixer, the differential current outputs of two
AD831s may be summed by connecting them together.
An integral low noise amplifier provides a single-ended voltage
output and can drive such low impedance loads as filters, 50 Ω
amplifier inputs, and A/D converters. Its small signal bandwidth
exceeds 200 MHz. A single resistor connected between pins
OUT and FB sets its gain. The amplifier’s low dc offset allows
its use in such direct-coupled applications as direct-to-baseband
conversion and quadrature-amplitude demodulation.
The mixer’s SSB noise figure is 10.3 dB at 70 MHz using its
output amplifier and optimum source impedance. Unlike passive mixers, the AD831 has no insertion loss and does not require an external diplexer or passive termination.
A programmable-bias feature allows the user to reduce power
consumption, with a reduction in the 1 dB compression point
and third-order intercept. This permits a tradeoff between dynamic range and power consumption. For example, the AD831
may be used as a second mixer in cellular and two-way radio
base stations at reduced power while still providing a substantial
performance improvement over passive solutions.
PRODUCT HIGHLIGHTS
1. –10 dBm LO Drive for a +24 dBm Output Referred Third
Order Intercept Point
2. Single-Ended Voltage Output
3. High Port-to-Port Isolation
4. No Insertion Loss
5. Single or Dual Supply Operation
6. 10.3 dB Noise Figure
REV. B
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
© Analog Devices, Inc., 1995
One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A.
Tel: 617/329-4700
Fax: 617/326-8703
AD831–SPECIFICATIONS
Parameter
RF INPUT
Bandwidth
1 dB Compression Point
Common-Mode Range
Bias Current
DC Input Resistance
Capacitance
IF OUTPUT
Bandwidth
Conversion Gain
Output Offset Voltage
Slew Rate
Output Voltage Swing
Short Circuit Current
LO INPUT
Bandwidth
Maximum Input Level
Common-Mode Range
Minimum Switching Level
Bias Current
Resistance
Capacitance
ISOLATION BETWEEN PORTS
LO to RF
LO to IF
RF to IF
DISTORTION AND NOISE
3rd Order Intercept
2rd Order Intercept
1 dB Compression Point
Noise Figure, SSB
POWER SUPPLIES
Recommended Supply Range
Quiescent Current1
(TA = +258C and 6VS = 65 V unless otherwise noted;
all values in dBm assume 50 V load.)
Conditions
Min
–10 dBm Signal Level, IP3 ≥ +20 dBm
10.7 MHz IF and High Side Injection
See Figure 1
Typ
400
10
DC Coupled
Differential or Common Mode
Single-Ended Voltage Output, –3 dB
Level = 0 dBm, R L = 100 Ω
Terminals OUT and VFB Connected
DC Measurement; LO Input Switched ± 1
Max
160
1.3
2
–40
RL = 100 Ω, Unity Gain
–10 dBm Input Signal Level
10.7 MHz IF and High Side Injection
200
0
15
300
± 1.4
75
MHz
±1
500
+40
400
–1
–1
Units
dBm
V
µA
kΩ
pF
MHz
dB
mV
V/µs
V
mA
MHz
+1
+1
V
V
mV p-p
µA
Ω
pF
Differential Input Signal
DC Coupled
Differential or Common Mode
200
17
500
2
LO = 100 MHz, RS = 50 Ω, 10.7 MHz IF
LO = 100 MHz, RS = 50 Ω, 10.7 MHz IF
RF = 100 MHz, RS = 50 Ω, 10.7 MHz IF
70
30
45
dB
dB
dB
LO = –10 dBm, f = 100 MHz, IF = 10.7 MHz
Output Referred, ± 100 mV LO Input
Output Referred, ± 100 mV LO Input
RL = 100 Ω, R BIAS = ∞
Matched Input, RF = 70 MHz, IF = 10.7 MHz
Matched Input, RF = 150 MHz, IF = 10.7 MHz
24
62
10
10.3
14
dBm
dBm
dBm
dB
dB
Dual Supply
Single Supply
For Best 3rd Order Intercept Point Performance
BIAS Pin Open Circuited
± 4.5
9
100
50
± 5.5
11
125
V
V
mA
NOTES
1
Quiescent current is programmable.
Specifications subject to change without notice.
–2–
REV. B
AD831
ABSOLUTE MAXIMUM RATINGS 1
PIN CONFIGURATION
Supply Voltage ± VS . . . . . . . . . . . . . . . . . . . . . . . . . . ± 5.5 V
Input Voltages
RFHI, RFLO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 3 V
LOHI, LOLO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 1 V
Internal Power Dissipation2 . . . . . . . . . . . . . . . . . . 1200 mW
Operating Temperature Range
AD831A . . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature Range (Soldering 60 sec) . . . . . . . . +300°C
Temperature
Range
Package
Description
Package
Option
AD831AP
–40°C to +85°C
20-Lead PLCC
P-20A
VP
IFP
20 19
AP
AN
1
18 COM
GND
4
VN
5
AD831
17 VFB
RFP
6
16 OUT
RFN
7
TOP VIEW
(Not to Scale)
VN
8
15 VN
GND
VP
10 11 12 13
LOP
9
VP
14 BIAS
Pin
Mnemonic
Description
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
VP
IFN
AN
GND
VN
RFP
RFN
VN
VP
LON
LOP
VP
GND
BIAS
VN
OUT
VFB
COM
AP
IFP
Positive Supply Input
Mixer Current Output
Amplifier Negative Input
Ground
Negative Supply Input
RF Input
RF Input
Negative Supply Input
Positive Supply Input
Local Oscillator Input
Local Oscillator Input
Positive Supply Input
Ground
Bias Input
Negative Supply Input
Amplifier Output
Amplifier Feedback Input
Amplifier Output Common
Amplifier Positive Input
Mixer Current Output
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the AD831 features proprietary ESD protection circuitry, permanent damage may
occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.
REV. B
2
PIN DESCRIPTION
ORDERING GUIDE
Model
3
LON
NOTES
1
Stresses above those listed under “Absolute Maximum Ratings” may cause
permanent damage to the device. This is a stress rating only and functional
operation of the device at these or any other conditions above those indicated in the
operational section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
2
Thermal Characteristics:
20-Pin PLCC Package: θJA = 110°C/Watt; θJC = 20°C/Watt.
Note that the θJA = 110°C/W value is for the package measured while suspended
in still air; mounted on a PC board, the typical value is θJA = 90°C/W due to the
conduction provided by the AD831’s package being in contact with the board,
which serves as a heat sink.
IFN
20-Lead PLCC
–3–
WARNING!
ESD SENSITIVE DEVICE
AD831–Typical Characteristics
65
SECOND ORDER INTERCEPT – dBm
THIRD ORDER INTERCEPT – dBm
30
25
20
15
10
5
0
10
100
FREQUENCY – MHz
63
62
61
60
10
1000
100
FREQUENCY – MHz
90
80
80
70
70
ISOLATION – dB
60
50
40
30
60
50
40
30
20
20
10
10
0
10
100
FREQUENCY – MHz
0
10
1000
100
FREQUENCY – MHz
1000
Figure 5. LO-to-RF Isolation vs. Frequency
Figure 2. IF-to-RF Isolation vs. Frequency
80
60
3 x RF-to-IF
2 x LO-to-IF
3 x RF-to-IF
70
50
2 x RF-to-IF
60
3 x LO-to-IF
40
ISOLATION – dB
ISOLATION – dB
1000
Figure 4. Second-Order Intercept vs. Frequency
Figure 1. Third-Order Intercept vs. Frequency,
IF Held Constant at 10.7 MHz
ISOLATION – dB
64
LO
30
20
2 x RF-to-IF
50
RF-to-IF
40
RF-to-IF
30
20
10
0
10
10
100
FREQUENCY – MHz
0
10
1000
100
FREQUENCY – MHz
1000
Figure 6. RF-to-IF Isolation vs. Frequency
Figure 3. LO-to-IF Isolation vs. Frequency
–4–
REV. B
AD831
1.00
12
0.50
GAIN ERROR – dB
1dB COMPRESSION POINT – dBm
0.75
10
8
6
4
0.25
0.00
–0.25
–0.50
2
–0.75
0
10
100
FREQUENCY – MHz
–1.00
10
1000
Figure 7. 1 dB Compression Point vs. Frequency, Gain = 1
100
FREQUENCY – MHz
1000
Figure 10. Gain Error vs. Frequency, Gain = 1
12
9
1dB COMPRESSION POINT – dBm
1dB COMPRESSION POINT – dBm
8
10
8
6
4
2
7
6
5
4
3
2
1
0
10
100
FREQUENCY – MHz
0
10
1000
11
MIXER OUTPUT
TRANSFORMER
COUPLED PER FIGURE 18
VS = 9V
1dB COMPRESSION POINT – dBm
THIRD ORDER INTERCEPT – dBm
25
19
16
MIXER PLUS AMPLIFIER,
G=1
13
10
100
10
VS = 8V
9
8
LO LEVEL = –10dBm
IF = 10.7MHz
7
150
200
250
FREQUENCY – MHz
300
350
0
100
200
300
400
FREQUENCY – MHz
500
600
Figure 12. Input 1 dB Compression Point vs. Frequency,
Gain = 1, 9 V Single Supply
Figure 9. Third-Order Intercept vs. Frequency , LO Held
Constant at 241 MHz
REV. B
1000
Figure 11. 1 dB Compression Point vs. Frequency, Gain = 4
Figure 8. 1 dB Compression Point vs. RF Input, Gain = 2
22
100
FREQUENCY – MHz
–5–
AD831–Typical Characteristics
30
1200
INPUT RESISTANCE
25
VS = 8V
20
LO LEVEL = –10dBm
IF = 10.7MHz
∆f = 20kHz
VS = 9V
15
0
50
100
150
200 250 300 350
FREQUENCY – MHz
400
450
INPUT CAPACITANCE
800
3.5
600
3.0
400
2.5
200
2.0
0
50
500
Figure 13. Input Third Order Intercept, 9 V Single Supply
100
150
FREQUENCY – MHz
200
250
Figure 15. Input Impedance vs. Frequency, ZIN = R iC
62.4
18
VS = 9V
62.2
17
62.0
16
61.8
VS = 8V
61.6
NOISE FIGURE – dB
SECOND ORDER INTERCEPT – dBm
4.0
INPUT CAPACITANCE – pF
INPUT RESISTANCE – Ohms
THIRD ORDER INTERCEPT – dBm
1000
61.4
61.2
61.0
60.8
LO LEVEL = –10dBm
IF = 10.7MHz
∆f = 20kHz
60.6
15
14
13
12
11
10
60.4
9
60.2
0
50
100
150
200 250 300 350
FREQUENCY – MHz
400
450
8
50
500
Figure 14. Input Second Order Intercept,
9 V Single Supply
100
150
FREQUENCY – MHz
200
250
Figure 16. Noise Figure vs. Frequency,
Matched Input
–6–
REV. B
AD831
THEORY OF OPERATION
When the integral output amplifier is used, pins IFN and IFP
are connected directly to pins AFN and AFP; the on-chip load
resistors convert the output current into a voltage that drives the
output amplifier. The ratio of these load resistors to resistors
R1, R2 provides nominal unity gain (0 dB) from RF to IF. The
expression for the gain, in decibels, is
The AD831 consists of a mixer core, a limiting amplifier, a low
noise output amplifier, and a bias circuit (Figure 17).
The mixer’s RF input is converted into differential currents by a
highly linear, Class A voltage-to-current converter, formed by
transistors Q1, Q2 and resistors R1, R2. The resulting currents
drive the differential pairs Q3, Q4 and Q5, Q6. The LO input is
through a high gain, low noise limiting amplifier that converts
the –10 dBm LO input into a square wave. This square wave
drives the differential pairs Q3, Q4 and Q5, Q6 and produces a
high level output at IFP and IFN—consisting of the sum and
difference frequencies of the RF and LO inputs—and a series of
lower level outputs caused by odd harmonics of the LO frequency mixing with the RF input.
 4   1  π
G dB = 20 log 10      
 π  2  2 
Equation 1
where
4
is the amplitude of the fundamental component of a square wave
π
1
is the conversion loss
2
π
is the small signal dc gain of the AD831 when the LO input
2
An on-chip network supplies the bias current to the RF and LO
inputs when these are ac coupled; this network is disabled when
the AD831 is dc coupled.
is driven fully positive or negative.
VP
1
AP 19
3
20
2
IFP
18mA TYP
AN
50Ω
50Ω
20Ω
20Ω
IFN
18mA TYP
BIAS
AO
LOP 11
LOCAL
OSCILLATOR
LON 10
INPUT
Q3
Q4
Q5
Q6
50Ω
LIMITING
AMPLIFIER
RFP
RF
INPUT
RFN
VP
BIAS
6
Q2
R4
1kΩ
R5
1kΩ
5kΩ
BIAS
CURRENT
50Ω
Q1
7
R1
20Ω
CURRENT
MIRROR
BIAS
R2
20Ω
36Ω
Q7
R3
26Ω
VN
36mA TYP
12mA TYP
Figure 17. Simplified Schematic Diagram
REV. B
16
OUT
17
VFB
18
COM
5kΩ
–7–
27mA TYP
AD831
The mixer has two open-collector outputs (differential currents) at pins IFN and IFP. These currents may be used to provide nominal unity RF-to-IF gain by connecting a center-tapped
transformer (1:1 turns ratio) to pins IFN and IFP as shown in
Figure 18.
Low-Pass Filtering
A simple low-pass filter may be added between the mixer and
the output amplifier by shunting the internal resistive loads (an
equivalent resistance of about 14 Ω with a tolerance of 20%)
with external capacitors; these attenuate the sum component in
a down-conversion application (Figure 20). The corner frequency of this one-pole low-pass filter (f = (2 π RCF)–1) should
be placed about an octave above the difference frequency IF.
Thus, for a 70 MHz IF, a –3 dB frequency of 140 MHz might
be chosen, using CF = (2 × π × 14 Ω × 140 MHz)–1 ≈ 82 pF, the
nearest standard value.
IF OUTPUT
MCLT4-1H
VP
VPOS
1
IFP 20
18mA TYP
IFN
2
18mA TYP
CF =
RFP
RF
INPUT RFN
6
Q4
Q3
LOP 11
LOCAL
OSCILLATOR
LON 10
INPUT
R4
1kΩ
7
R5
1kΩ
R1
20Ω
Q1
4
GND
5
VN
CF
2
AN
50Ω
20
1
IFN
VP
19
IFP
50Ω
AP
COM
18
5kΩ
R2
20Ω
BIAS
CURRENT
BIAS
CF
5kΩ
Q6
3
LIMITING
AMPLIFIER
Q2
VP
Q5
1
1
=
89.7 f
2πfR
RFP
6
Q7
R3
26Ω
7
VN
VFB
OUT
16
VN 15
AD831
RFN
36mA TYP
17
Top View
VN
8
Figure 18. Connections for Transformer Coupling to the IF
Output
BIAS 14
VP
LON
9
LOP
10
11
VP
GND
12
13
Programming the Bias Current
Figure 20. Low-Pass Filtering Using External Capacitors
Because the AD831’s RF port is a Class-A circuit, the maximum RF input is proportional to the bias current. This bias current may be reduced by connecting a resistor from the BIAS pin
to the positive supply (Figure 19). For normal operation, the
BIAS pin is left unconnected. For lowest power consumption,
the BIAS pin is connected directly to the positive supply. The
range of adjustment is 100 mA for normal operation to
45 mA total current at minimum power consumption.
2
3
AN
50Ω
4
5
6
7
20
1
IFN
VP
COM
VFB
VN
RFP
OUT
AN
50Ω
18
17
16
VN 15
AD831
VN
VP
9
10
LOP
11
GND
12
13
GND
5
VN
20
1
IFN
VP
19
IFP
50Ω
AP
COM
VFB
RFP
OUT
18
17
16
IF
OUTPUT
VPOS
7
1.33kΩ
VP
4
6
0.1µF
VN 15
AD831
RFN
Top View
BIAS 14
LON
2
3
AP
Top View
8
The AD831’s output amplifier converts the mixer core’s differential current output into a single-ended voltage and provides
an output as high as ± 1 V peak into a 50 Ω load (+10 dBm).
For unity gain operation (Figure 21), the inputs AN and AP
connect to the open-collector outputs of the mixer’s core and
OUT connects to VFB.
19
IFP
50Ω
GND
RFN
Using the Output Amplifier
8
NOTE ADDED
RESISTOR
VN
BIAS 14
VP
9
Figure 19. Programming the Quiescent Current
LON
10
LOP
11
VP
GND
12
13
Figure 21. Output Amplifier Connected for Unity Gain
Operation
–8–
REV. B
AD831
For gains other than unity, the amplifier’s output at OUT is
connected via an attenuator network to VFB; this determines
the overall gain. Using resistors R1 and R2 (Figure 22), the gain
setting expression is
 R1 + R2 


 R2 
G dB = 20 log 10
2
3
AN
50Ω
Equation 2
4
GND
5
VN
6
20
1
IFN
VP
19
IFP
50Ω
AP
COM
VFB
RFP
OUT
18
R2
51.1Ω
17
R1
110Ω
16
IF
OUTPUT
BPF
RT
2
3
20
1
AN
IFN
50Ω
VP
19
IFP
50Ω
7
AP
COM
4 GND
VFB
6
7
RT
Top View
8 VN
18
BIAS 14
R2
5 VN
VN 15
AD831
RFN
VP
17
9
LON
10
LOP
11
VP
GND
12
13
R1
RFP
OUT
IF
OUTPUT
Figure 23. Connections for Driving a Doubly-Terminated
Bandpass Filter
VN 15
AD831
RFN
16
Higher gains can be achieved, using different resistor ratios, but
with concomitant reduction in the bandwidth of this amplifier
(Figure 24). Note also that the Johnson noise of these gain-setting resistors, as well as that of the BPF terminating resistors, is
ultimately reflected back to the mixer’s input; thus they should
be as small as possible, consistent with the permissible loading
on the amplifier’s output.
Top View
8 VN
BIAS 14
VP
9
LON
10
LOP
11
VP
GND
12
13
Figure 22. Output Amplifier Feedback Connections for
Increasing Gain
Driving Filters
The output amplifier can be used for driving reverse-terminated
loads. When driving an IF bandpass filter (BPF), for example,
proper attention must be paid to providing the optimal source
and load terminations so as to achieve the specified filter response. The AD831’s wideband highly linear output amplifier
affords an opportunity to increase the RF-to-IF gain to compensate for a filter’s insertion and termination losses.
12
1dB COMPRESSION POINT – dBm
G=1
Figure 23 indicates how the output amplifier’s low impedance
(voltage source) output can drive a doubly-terminated bandpass
filter. The typical 10 dB of loss (4 dB of insertion loss and 6 dB
due to the reverse-termination) be made up by the inclusion of a
feedback network that increases the gain of the amplifier by
10 dB (×3.162). When constructing a feedback circuit, the signal path between OUT and VFB should be as short as possible.
10
G=2
8
G=4
6
4
2
0
10
100
FREQUENCY – MHz
1000
Figure 24. Output Amplifier 1 dB Compression Point for
Gains of 1, 2, and 4 (Gains of 0 dB, 6 dB, and 12 dB,
Respectively)
REV. B
–9–
AD831
APPLICATIONS
The RF input to the AD831 is shown connected by an impedance matching network for an assumed source impedance of
50 Ω. Figure 15 shows the input impedance of the AD831 plotted vs. frequency. The input circuit can be modeled as a resistance in parallel with a capacitance. The 82 pF capacitors (CF)
connected from IFN and IFP to VP provide a low-pass filter
with a cutoff frequency of approximately 140 MHz in downconversion applications (see the Theory of Operation section of
this data sheet for more details). The LO input is connected
single-ended because the limiting amplifier provides a symmetric drive to the mixer. To minimize intermodulation distortion,
connect pins OUT and VFB by the shortest possible path. The
connections shown are for unity-gain operation.
Careful component selection, circuit layout, power supply
decoupling, and shielding are needed to minimize the AD831’s
susceptibility to interference from radio and TV stations, etc. In
bench evaluation, we recommend placing all of the components
in a shielded box and using feedthrough decoupling networks
for the supply voltage.
Circuit layout and construction are also critical, since stray capacitances and lead inductances can form resonant circuits and
are a potential source of circuit peaking, oscillation, or both.
Dual-Supply Operation
Figure 25 shows the connections for dual supply operation.
Supplies may be as low as ± 4.5 V but should be no higher than
± 5.5 V due to power dissipation.
At LO frequencies less than 100 MHz, the AD831’s LO power
may be as low as –20 dBm for satisfactory operation. Above
100 MHz, the specified LO power of –10 dBm must be used.
+5V
0.1µF
CF
CF
82pF 82pF
2
3
AN
50Ω
4
GND
5
VN
20
1
IFN
VP
19
IFP
50Ω
AP
COM
C1
RF
INPUT
C2
–5V
VFB
RFP
6
L1
18
51.1Ω
0.1µF
7
OUT
110Ω
8 VN
–5V
–5V
RT
BIAS 14 NC
VP
9
+5V
IF
OUTPUT
BPF
0.1µF
Top View
0.1µF
RT
16
VN 15
AD831
RFN
17
LON
LOP
10
11
51.1Ω
VP
GND
12
13
0.1µF
0.1µF
+5V
LO INPUT
–10 dBm
Figure 25. Connections for ± 5 V Dual-Supply Operation Showing Impedance
Matching Network and Gain of 2 for Driving Reverse-Terminated IF Filter
–10–
REV. B
AD831
Single Supply Operation
In single supply operation, the COM terminal is the “ground”
reference for the output amplifier and must be biased to 1/2 the
supply voltage, which is done by resistors R1 and R2. The OUT
pin must be ac-coupled to the load.
Figure 26 is similar to the dual supply circuit in Figure 19. Supplies may be as low as 9 V but should not be higher than
11 V due to power dissipation. As in Figure 19, both the RF
and LO ports are driven single-ended and terminated.
+9V
0.1µF
82pF
82pF
+5V
2
3
AN
50Ω
C1
4
GND
5
VN
C2
RF
INPUT
IFN
VP
19
IFP
50Ω
AP
COM
VFB
RFP
6
L1
20
1
OUT
18
5kΩ
R2
51.1Ω
5kΩ
0.1µF
17
RT
16
0.1µF
7
VN 15
AD831
RFN
Top View
8 VN
BIAS 14 NC
VP
9
LON
10
LOP
11
0.1µF
+9V
0.1µF
VP
GND
12
13
0.1µF
51.1Ω
0.1µF
+9V
LO INPUT
–10 dBm
Figure 26. Connections for +9 V Single-Supply Operation
REV. B
–11–
R1
110Ω
CC
IF
OUTPUT
AD831
(Q) outputs. The mixers’ inputs may be connected in parallel
and a single termination resistor used if the mixers are located in
close proximity on the PC board.
Connections Quadrature Demodulation
Two AD831 mixers may have their RF inputs connected in parallel and have their LO inputs driven in phase quadrature (Figure 27) to provide demodulated in-phase (I) and quadrature
+5V
0.1µF
CF
CF
2
3
AN
50Ω
4
GND
5
VN
20
1
IFN
19
VP
IFP
50Ω
AP
COM
0.1µF
–5V
VFB
RFP
6
7
OUT
17
VN
8
–5V
–5V
0.1µF
Top View
0.1µF
DEMODULATED
QUADRATURE
OUTPUT
16
VN 15
AD831
RFN
18
BIAS 14 NC
VP
LON
9
LOP
10
11
GND
13
0.1µF
51.1Ω
+5V
VP
12
0.1µF
+5V
LO INPUT
AT 90°
–10 dBm
IF
INPUT
+5V
51.1Ω
0.1µF
CF
CF
2
3
AN
50Ω
4
GND
5
VN
20
1
IFN
VP
19
IFP
50Ω
AP
COM
0.1µF
–5V
VFB
RFP
6
7
OUT
17
VN
8
–5V
BIAS 14 NC
VP
9
+5V
–5V
0.1µF
Top View
0.1µF
DEMODULATED
IN-PHASE
OUTPUT
16
VN 15
AD831
RFN
18
LON
10
LOP
11
51.1Ω
VP
GND
12
13
0.1µF
0.1µF
+5V
LO INPUT
AT 0°
–10 dBm
Figure 27. Connections for Quadrature Demodulation
–12–
REV. B
AD831
Table I. AD831 Mixer Table, 64.5 V Supplies, LO = –9 dBm
LO Level
–9.0 dBm, LO Frequency 130.7 MHz, Data File imdTB10771
RF Level
0.0 dBm, RF Frequency 120 MHz
Temperature Ambient
Dut Supply
± 4.50 V
VPOS Current 90 mA
VNEG Current 91 mA
Intermodulation Table RF harmonics (rows) × LO harmonics (columns).
First row absolute value of nRF-mLO, and second row is the sum.
0
0
1
2
3
4
5
6
7
–32.7
–32.7
–35.7
–35.7
–21.1
–21.1
–11.6
–11.6
–19.2
–19.2
–35.1
–35.1
–41.9
–41.9
1
–31.6
–31.6
0.0
–28.5
–37.2
–26.7
–41.5
–28.0
–30.4
–27.2
–34.3
–33.2
–25.2
–34.3
–40.1
–44.8
2
–45.3
–45.3
–48.2
–42.4
–39.4
–49.4
–57.6
–42.5
–44.9
–51.1
–42.4
–46.2
–40.2
–58.1
–40.2
–61.6
3
–54.5
–54.5
–57.1
–65.5
–57.5
–46.0
–50.6
–63.7
–62.6
–60.6
–55.8
–69.6
–59.7
–72.7
–55.2
–73.5
4
–67.1
–67.1
–63.1
–53.6
–69.9
–72.9
–69.9
–71.2
–69.6
–70.1
–74.1
–72.6
–69.7
–73.5
–58.6
–72.7
5
–53.5
–53.5
–62.6
–68.4
–73.8
–70.8
–72.3
–72.8
–70.7
–73.4
–71.1
–73.2
–74.3
–73.3
–73.0
–72.5
6
–73.6
–73.6
–57.7
–73.5
–68.6
–72.7
–73.1
–73.5
–73.8
–73.6
–73.0
–73.1
–72.9
–72.4
–74.4
–73.7
7
–73.8
–73.8
–73.9
–73.8
–63.4
–73.2
–72.6
–73.8
–74.6
–72.6
–74.9
–73.7
–73.6
–73.5
–74.5
–72.9
Table II. AD831 Mixer Table, 65 V Supplies, LO = –9 dBm
LO Level
–9.0 dBm, LO Frequency 130.7 MHz, Data File imdTB13882
RF Level
0.0 dBm, RF Frequency 120 MHz
Temperature Ambient
Dut Supply
± 5.00 V
VPOS Current 102 mA
VNEG Current 102 mA
Intermodulation table RF harmonics (rows) × LO harmonics (columns).
First row absolute value of nRF-mLO, and second row is the sum.
0
0
1
2
3
4
5
6
7
–36.5
–36.5
–46.5
–46.5
–33.0
–33.0
–17.0
–17.0
–23.0
–23.0
–34.2
–34.2
–45.6
–45.6
1
–37.5
–37.5
0.0
–29.1
–41.2
–38.7
–41.1
–22.9
–38.5
–28.4
–29.0
–35.3
–31.7
–34.3
–47.4
–52.4
2
–45.9
–45.9
–45.2
–39.4
–47.6
–35.7
–61.5
–38.4
–53.7
–42.3
–43.5
–53.7
–41.5
–52.8
–41.8
–66.3
3
–46.4
–46.4
–53.0
–40.0
–67.0
–50.0
–43.0
–48.9
–60.9
–57.8
–47.9
–57.0
–50.7
–71.8
–41.0
–67.4
4
–45.1
–45.1
–56.0
–39.0
–48.7
–48.1
–64.6
–58.4
–53.5
–56.1
–55.7
–63.8
–53.5
–70.5
–51.1
–67.6
5
–35.2
–35.2
–45.3
–53.0
–54.1
–62.4
–54.1
–67.3
–53.7
–67.0
–57.9
–69.4
–66.6
–73.2
–64.3
–72.9
6
–63.4
–63.4
–41.1
–66.3
–53.6
–67.2
–66.5
–67.5
–58.8
–72.9
–63.3
–71.2
–61.7
–71.7
–71.4
–73.2
7
–67.3
–67.3
–65.8
–61.6
–37.8
–66.3
–54.6
–72.9
–62.5
–71.4
–71.7
–70.7
–55.2
–72.1
–57.1
–73.1
REV. B
–13–
AD831
Table III. AD831 Mixer Table, 63.5 V Supplies, LO = –20 dBm
LO Level
–20.0 dBm, LO Frequency 130.7 MHz, Data File G1T1K 0771
RF Level
0.0 dBm, RF Frequency 120 MHz
Temperature Ambient
Dut Supply
± 3.50 V
VPOS Current 55 mA
VNEG Current 57 mA
Intermodulation Table RF harmonics (rows) × LO harmonics (columns).
First row absolute value of nRF-mLO, and second row is the sum.
0
0
1
2
3
4
5
6
7
–45.2
–45.2
–35.7
–35.7
–16.1
–16.1
–21.6
–21.6
–22.3
–22.3
–32.0
–32.0
–36.4
–36.4
1
–30.3
–30.3
0.0
–29.7
–33.7
–28.2
–47.9
–24.4
–37.5
–26.0
–33.8
–47.4
–32.0
–35.9
–45.2
–49.7
2
–50.3
–50.3
–49.4
–41.0
–47.4
–51.4
–49.9
–34.7
–48.8
–49.8
–38.5
–48.6
–40.7
–68.5
–51.0
–67.9
3
–48.4
–48.4
–55.7
–52.9
–58.2
–50.0
–45.0
–64.5
–57.0
–62.8
–68.4
–73.4
–55.5
–74.0
–47.7
–71.8
4
–66.7
–66.7
–59.7
–65.9
–67.2
–78.1
–62.8
–74.2
–58.2
–77.5
–71.5
–74.4
–72.9
–77.9
–63.5
–77.5
5
–66.9
–66.9
–71.5
–76.3
–73.6
–78.1
–77.6
–78.2
–70.8
–78.1
–70.2
–78.0
–75.8
–77.9
–78.1
–77.9
6
–78.0
–78.0
–69.7
–78.3
–76.7
–78.3
–78.6
–78.2
–78.8
–78.1
–75.4
–78.0
–78.1
–77.9
–79.0
–77.8
7
–78.4
–78.4
–78.5
–78.3
–76.9
–78.2
–78.7
–78.2
–79.0
–77.9
–79.1
–77.9
–78.6
–77.8
–78.9
–77.5
Table IV. AD831 Mixer Table, 65 V Supplies, 1 kV Bias Resistor, LO = –20 dBm
LO Level
–20.0 dBm, LO Frequency 130.7 MHz, Data File G1T1K 3881
RF Level
0.0 dBm, RF Frequency 120 MHz
Temperature Ambient
Dut Supply
± 3.50 V
VPOS Current 59 mA
VNEG Current 61 mA
Intermodulation table RF harmonics (rows) × LO harmonics (columns).
First row absolute value of nRF-mLO, and second row is the sum.
0
0
1
2
3
4
5
6
7
–60.6
–60.6
–52.3
–52.3
–16.6
–16.6
–12.8
–12.8
–26.0
–26.0
–45.0
–45.0
–38.8
–38.8
1
–34.1
–34.1
0.0
–27.3
–35.2
–28.7
–41.8
–20.7
–29.8
–32.9
–29.1
–39.2
–35.3
–38.2
–49.0
–47.8
2
–46.6
–46.6
–48.8
–37.8
–40.1
–47.6
–52.2
–41.7
–57.9
–54.2
–38.6
–50.4
–45.8
–64.1
–47.7
–64.9
3
–41.3
–41.3
–58.8
–47.9
–59.5
–65.2
–41.8
–62.5
–61.2
–64.2
–58.1
–73.8
–57.5
–72.3
–54.0
–72.6
4
–53.9
–53.9
–52.5
–61.4
–73.7
–70.6
–68.1
–76.9
–60.3
–76.8
–71.0
–78.6
–63.4
–78.3
–62.3
–78.1
5
–66.9
–66.9
–65.8
–69.7
–76.6
–72.9
–75.2
–77.4
–65.4
–77.7
–70.0
–78.5
–73.6
–78.4
–68.7
–78.2
6
–77.4
–77.4
–73.3
–78.6
–73.8
–78.7
–78.8
–78.6
–79.2
–78.6
–73.6
–78.4
–74.9
–78.2
–79.3
–78.2
7
–78.9
–78.9
–79.0
–78.8
–77.9
–78.7
–78.0
–78.6
–79.3
–78.3
–79.5
–78.3
–79.3
–78.1
–79.3
–78.0
–14–
REV. B
AD831
HP 6632A
PROGRAMMABLE
POWER SUPPLY
HP 6632A
PROGRAMMABLE
POWER SUPPLY
HP 8656B
SYNTHESIZED
SIGNAL GENERATOR
–5V
+5V
MCL
ZFSC-2-1
COMBINER
AD831
∑
50Ω
HP 8561E
SPECTRUM
ANALYZER
PER
FIGURE 25
LO
HP 8656A
SYNTHESIZED
SIGNAL GENERATOR
FLUKE 6082A
SYNTHESIZED
SIGNAL GENERATOR
HP 9920
IEEE CONTROLLER
HP 9121
DISK DRIVE
IEEE-488 BUS
Figure 28. Third-Order Intercept Characterization Setup
HP 6632A
PROGRAMMABLE
POWER SUPPLY
HP 6632A
PROGRAMMABLE
POWER SUPPLY
–5V
+5V
MCL
ZFSC-2-1
RF
HP 8656B
SYNTHESIZED
SIGNAL GENERATOR
AD831
PER
FIGURE 25
IF
LO
HP 8656B
SYNTHESIZED
SIGNAL GENERATOR
50Ω
50Ω
50Ω
MCL
ZFSC-2-1
50Ω
HP 8561E
SPECTRUM
ANALYZER
USED FOR
IF TO RF, LO
LO TO RF
MOVE SPECTRUM
ANALYZER FOR IF
MEASUREMENTS
HP 8656B
SYNTHESIZED
SIGNAL GENERATOR
Figure 29. IF to RF Isolation Characterization Setup
REV. B
–15–
AD831
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
20-Lead PLCC (P-20A)
0.180 (4.57)
0.165 (4.19)
0.056 (1.42)
0.042 (1.07)
C1879a–10–7/95
0.048 (1.21)
0.042 (1.07)
0.025 (0.63)
0.015 (0.38)
0.048 (1.21)
0.042 (1.07)
3
PIN 1
IDENTIFIER
4
0.050
(1.27)
BSC
0.021 (0.53)
0.013 (0.33)
18
0.330 (8.38)
0.290 (7.37)
TOP VIEW
0.032 (0.81)
0.026 (0.66)
14
8
13
0.040 (1.01)
0.025 (0.64)
0.356 (9.04)
SQ
0.350 (8.89)
0.110 (2.79)
0.085 (2.16)
0.395 (10.02)
SQ
0.385 (9.78)
PRINTED IN U.S.A.
9
0.020
(0.50)
R
C1879a–10–6/95
19
–16–
REV. B