ANALOG DEVICES AD630 Data Sheet

Balanced Modulator/Demodulator

AD630

FUNCTIONAL BLOCK DIAGRAM

FEATURES Recovers Signal from 100 d B Noise

CM OFF CM OFF DIFF OFF DIFF OFF

2 MHz Channel Bandwidth ADJ ADJ ADJ ADJ 45 V/s Slew Rate

–120 d B Crosstalk @ 1 k Hz RINA

AD630

AMP A

Pin Programmable, Closed-Loop Gains of 1 and 2

CH A+ COMP

0.05% Closed-Loop Gain Accuracy and Match

CH A–

100 V Channel Offset Voltage (AD630BD)

350 k Hz Full Power Bandwidth RINB

AMP B

Chips Available 10k

CH B+

CH B– –V RB

PRODUCT DESCRIPTION

The AD630 is a high precision balanced modulator that combines

a flexible commutating architecture with the accuracy and tem-

COMP CHANNEL

perature stability afforded by laser wafer trimmed thin film

STATUS

SEL B

resistors. Its signal processing applications include balanced B/A

SEL A

modulation and demodulation, synchronous detection, phase detection, quadrature detection, phase-sensitive detection,

lock-in amplification, and square wave multiplication. A network of on-board applications resistors provides precision closed-loop

PRODUCT HIGHLIGHTS

gains of ± 1 and ± 2 with 0.05% accuracy (AD630B). These

1. The configuration of the AD630 makes it ideal for signal

resistors may also be used to accurately configure multiplexer

processing applications, such as balanced modulation and

gains of +1, +2, +3, or +4. Alternatively, external feedback may

demodulation, lock-in amplification, phase detection, and

be employed, allowing the designer to implement high gain or

square wave multiplication.

complex switched feedback topologies.

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2. The application flexibility of the AD630 makes it the best

The AD630 can be thought of as a precision op amp with two

choice for applications that require precisely fixed gain,

independent differential input stages and a precision comparator

switched gain, multiplexing, integrating-switching functions,

that is used to select the active front end. The rapid response

and high speed precision amplification.

time of this comparator coupled with the high slew rate and fast settling of the linear amplifiers minimize switching distortion. In 3. The 100 d B dynamic range of the AD630 exceeds that of any addition, the AD630 has extremely low crosstalk between chan- hybrid or IC balanced modulator/demodulator and is compa- nels of –100 d B @ 10 k Hz. rable to that of costly signal processing instruments. The AD630 is used in precision signal processing and instru- 4. The op amp format of the AD630 ensures easy implementa- mentation applications that require wide dynamic range. When tion of high gain or complex switched feedback functions. used as a synchronous demodulator in a lock-in amplifier The application resistors facilitate the implementation of configuration, it can recover a small signal from 100 d B of inter- most common applications with no additional parts. fering noise (see Lock-In Amplifier Applications section). Although

5. The AD630 can be used as a 2-channel multiplexer with

optimized for operation up to 1 k Hz, the circuit is useful at

gains of +1, +2, +3, or +4. The channel separation of

frequencies up to several hundred kilohertz.

100 d B @ 10 k Hz approaches the limit achievable with an

Other features of the AD630 include pin programmable frequency empty IC package. compensation, optional input bias current compensation resis-

6. The AD630 has pin strappable frequency compensation (no

tors, common-mode and differential-offset voltage adjustment,

external capacitor required) for stable operation at unity gain

and a channel status output that indicates which of the two

without sacrificing dynamic performance at higher gains.

differential inputs is active. This device is now available to

Standard Military Drawing (DESC) numbers 5962-8980701RA 7. Laser trimming of comparator and amplifying channel offsets eliminates the need for external nulling in most cases.

and 5962-89807012A.

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