Analog Devices AD831AP Datasheet

IFN

IFP

GND

RFP

RFN

LON

LOP

GND

BIAS

OUT

VFB

COM

AD831

50Ω

139 10 11 12

123

Low Distortion Mixer

AD831

FEATURES

FUNCTIONAL BLOCK DIAGRAM

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

APPLICATIONS High Performance RF/IF Mixer Direct to Baseband Conversion Image-Reject Mixers I/Q Modulators and Demodulators

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

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

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.

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

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.

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

One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A. Tel: 617/329-4700 Fax: 617/326-8703

(TA = +258C and 6VS = 65 V unless otherwise noted;

AD831–SPECIFICA TIONS

all values in dBm assume 50 V load.)

Parameter Conditions Min Typ Max Units

RF INPUT

Bandwidth –10 dBm Signal Level, IP3 ≥ +20 dBm 400 MHz

10.7 MHz IF and High Side Injection

See Figure 1 1 dB Compression Point 10 dBm Common-Mode Range ±1V Bias Current DC Coupled 160 500 µA DC Input Resistance Differential or Common Mode 1.3 kΩ Capacitance 2pF

IF OUTPUT

Bandwidth Single-Ended Voltage Output, –3 dB

Level = 0 dBm,

RL = 100 Ω 200 MHz Conversion Gain Terminals OUT and VFB Connected 0 dB Output Offset Voltage DC Measurement; LO Input Switched ± 1 –40 15 +40 mV Slew Rate 300 V/µs Output Voltage Swing R

= 100 Ω, Unity Gain ±1.4 V

Short Circuit Current 75 mA

LO INPUT

Bandwidth –10 dBm Input Signal Level 400 MHz

10.7 MHz IF and High Side Injection Maximum Input Level –1 +1 V Common-Mode Range –1 +1 V Minimum Switching Level Differential Input Signal 200 mV p-p Bias Current DC Coupled 17 50 µA Resistance Differential or Common Mode 500 Ω Capacitance 2pF

ISOLATION BETWEEN PORTS

LO to RF LO = 100 MHz, R LO to IF LO = 100 MHz, R

= 50 Ω, 10.7 MHz IF 70 dB

= 50 Ω, 10.7 MHz IF 30 dB

RF to IF RF = 100 MHz, RS = 50 Ω, 10.7 MHz IF 45 dB

DISTORTION AND NOISE LO = –10 dBm, f = 100 MHz, IF = 10.7 MHz

3rd Order Intercept Output Referred, ± 100 mV LO Input 24 dBm 2rd Order Intercept Output Referred, ± 100 mV LO Input 62 dBm 1 dB Compression Point R

= 100 Ω, R

= ∞ 10 dBm

BIAS

Noise Figure, SSB Matched Input, RF = 70 MHz, IF = 10.7 MHz 10.3 dB

Matched Input, RF = 150 MHz, IF = 10.7 MHz 14 dB

POWER SUPPLIES

Recommended Supply Range Dual Supply ±4.5 ±5.5 V

Single Supply 9 11 V For Best 3rd Order Intercept Point Performance 100 125 mA

Quiescent Current

BIAS Pin Open Circuited

NOTES

Quiescent current is programmable.

Specifications subject to change without notice.

–2–

REV. B

AD831

GND

RFP RFN

IFN

IFP

LON

GND

LOP

COM VFB

BIAS

OUT VN

1931220

4 5

6 7

12 1391110

18 17

16 15

TOP VIEW

(Not to Scale)

AD831

ABSOLUTE MAXIMUM RATINGS

Supply Voltage ±VS . . . . . . . . . . . . . . . . . . . . . . . . . . ±5.5 V

Input Voltages

RFHI, RFLO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±3 V

LOHI, LOLO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±1 V

Internal Power Dissipation

. . . . . . . . . . . . . . . . . . 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

NOTES

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.

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 θ conduction provided by the AD831’s package being in contact with the board, which serves as a heat sink.

= 90°C/W due to the

ORDERING GUIDE

Temperature Package Package

Model Range Description Option

AD831AP –40°C to +85°C 20-Lead PLCC P-20A

PIN CONFIGURATION

20-Lead PLCC

PIN DESCRIPTION

Pin Mnemonic Description

1 VP Positive Supply Input 2 IFN Mixer Current Output 3 AN Amplifier Negative Input 4 GND Ground 5 VN Negative Supply Input 6 RFP RF Input 7 RFN RF Input 8 VN Negative Supply Input

9 VP Positive Supply Input 10 LON Local Oscillator Input 11 LOP Local Oscillator Input 12 VP Positive Supply Input 13 GND Ground 14 BIAS Bias Input 15 VN Negative Supply Input 16 OUT Amplifier Output 17 VFB Amplifier Feedback Input 18 COM Amplifier Output Common 19 AP Amplifier Positive Input 20 IFP 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.

–3–

REV. B

WARNING!

ESD SENSITIVE DEVICE

AD831–Typical Characteristics

FREQUENCY – MHz

10 1000100

ISOLATION – dB

3 x RF-to-IF

2 x RF-to-IF

RF-to-IF

3 x RF-to-IF

2 x RF-to-IF

RF-to-IF

THIRD ORDER INTERCEPT – dBm

10 1000100

FREQUENCY – MHz

Figure 1. Third-Order Intercept vs. Frequency, IF Held Constant at 10.7 MHz

ISOLATION – dB

10 1000100

FREQUENCY – MHz

SECOND ORDER INTERCEPT – dBm

10 1000100

FREQUENCY – MHz

Figure 4. Second-Order Intercept vs. Frequency

ISOLATION – dB

10 1000100

FREQUENCY – MHz

Figure 2. IF-to-RF Isolation vs. Frequency

2 x LO-to-IF

3 x LO-to-IF

ISOLATION – dB

10 1000100

Figure 3. LO-to-IF Isolation vs. Frequency

FREQUENCY – MHz

–4–

Figure 5. LO-to-RF Isolation vs. Frequency

Figure 6. RF-to-IF Isolation vs. Frequency

REV. B

AD831

FREQUENCY – MHz

1dB COMPRESSION POINT – dBm

0 600100 200 300 400 500

LO LEVEL = –10dBm IF = 10.7MHz

= 8V

= 9V

1dB COMPRESSION POINT – dBm

10 1000100

FREQUENCY – MHz

Figure 7. 1 dB Compression Point vs. Frequency, Gain = 1

1dB COMPRESSION POINT – dBm

10 1000100

FREQUENCY – MHz

1.00

0.75

0.50

0.25

0.00

–0.25

GAIN ERROR – dB

–0.50

–0.75

–1.00

10 1000100

FREQUENCY – MHz

Figure 10. Gain Error vs. Frequency, Gain = 1

1dB COMPRESSION POINT – dBm

10 1000100

FREQUENCY – MHz

Figure 8. 1 dB Compression Point vs. RF Input, Gain = 2

MIXER OUTPUT TRANSFORMER

COUPLED PER FIGURE 18

REV. B

THIRD ORDER INTERCEPT – dBm

100 350250150 200 300

Figure 9. Third-Order Intercept vs. Frequency , LO Held Constant at 241 MHz

FREQUENCY – MHz

MIXER PLUS AMPLIFIER, G = 1

Figure 11. 1 dB Compression Pointvs.Frequency,Gain = 4

Figure 12. Input 1 dB Compression Point vs. Frequency,

Gain = 1, 9 V Single Supply

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