ANALOG DEVICES AD620 User Guide

Low Cost Low Power Instrumentation Amplifier

TO TA ER , P PM FU LL LE

AD620 FEATURES

CONNECTION DIAGRAM

Easy to use Gain set with one external resistor

RG RG

(Gain range 1 to 10,000)

–IN +VS

Wide power supply range (±2.3 V to ±18 V)

Higher performance than 3 op amp IA designs +IN OUTPUT

Available in 8-lead DIP and SOIC packaging –VS 5AD620 REF

Low power, 1.3 m A max supply current

TOP VIEW

Excellent dc performance (B grade) 50 µV max, input offset voltage 5- 0- Figure 1. 8-Lead PDIP (N), CERDIP (Q), and SOIC (R) Packages

0.6 µV/°C max, input offset drift

PRODUCT DESCRIPTION

1.0 n A max, input bias current

The AD620 is a low cost, high accuracy instrumentation

100 d B min common-mode rejection ratio (G = 10)

amplifier that requires only one external resistor to set gains of

Low noise

1 to 10,000. Furthermore, the AD620 features 8-lead SOIC and

9 n V/√Hz @ 1 k Hz, input voltage noise

DIP packaging that is smaller than discrete designs and offers

0.28 µV p-p noise (0.1 Hz to 10 Hz)

lower power (only 1.3 m A max supply current), making it a

Excellent ac specifications

good fit for battery-powered, portable (or remote) applications.

120 k Hz bandwidth (G = 100) 15 µs settling time to 0.01% The AD620, with its high accuracy of 40 ppm maximum

TI LT IS (0 .1 z) p- p) nonlinearity, low offset voltage of 50 µV max, and offset drift of

APPLICATIONS 0.6 µV/°C max, is ideal for use in precision data acquisition systems, such as weigh scales and transducer interfaces.

Weigh scales

Furthermore, the low noise, low input bias current, and low power

ECG and medical instrumentation

of the AD620 make it well suited for medical applications, such

Transducer interface

as ECG and noninvasive blood pressure monitors.

Data acquisition systems Industrial process controls

The low input bias current of 1.0 n A max is made possible with

Battery-powered and portable equipment

the use of Superϐeta processing in the input stage. The AD620 works well as a preamplifier due to its low input voltage noise of 9 n V/√Hz at 1 k Hz, 0.28 µV p-p in the 0.1 Hz to 10 Hz band, and 0.1 p A/√Hz input current noise. Also, the AD620 is well

suited for multiplexed applications with its settling time of 15 µs to 0.01%, and its cost is low enough to enable designs with one

in-amp per channel.

25,000 3 OP AMP

IN-AMP 1,000

(3 OP-07s) TYPICAL STANDARD

20,000 BIPOLAR INPUT IN-AMP

AD620A

AD620 SUPERβETA BIPOLAR INPUT IN-AMP

SUPPLY CURRENT (m A) SOURCE RESISTANCE (Ω)

Figure 2. Three Op Amp IA Designs vs. AD620

Figure 3. Total Voltage Noise vs. Source Resistance

Rev. G 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 that may result from its use.

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