CONNECTION DIAGRAM

8-Lead Plastic Mini-DIP (N), Cerdip (Q)

and SOIC (R) Packages

–IN

+IN

OUTPUT

REF

1

2

3

4

8

7

6

5

AD620

TOP VIEW

REV. E

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.

a

Low Cost, Low Power

Instrumentation Amplifier

AD620

FEATURES

EASY TO USE

Gain Set with One External Resistor

(Gain Range 1 to 1000)

Wide Power Supply Range ( 2.3 V to

18 V)

Higher Performance than Three Op Amp IA Designs

Available in 8-Lead DIP and SOIC Packaging

Low Power, 1.3 mA max Supply Current

EXCELLENT DC PERFORMANCE (“B GRADE”)

50

V max, Input Offset Voltage

0.6

V/ C max, Input Offset Drift

1.0 nA max, Input Bias Current

100 dB min Common-Mode Rejection Ratio (G = 10)

LOW NOISE

9 nV/

√Hz, @ 1 kHz, Input Voltage Noise

0.28

V p-p Noise (0.1 Hz to 10 Hz)

EXCELLENT AC SPECIFICATIONS

120 kHz Bandwidth (G = 100)

15

s Settling Time to 0.01%

APPLICATIONS

Weigh Scales

ECG and Medical Instrumentation

Transducer Interface

Data Acquisition Systems

Industrial Process Controls

Battery Powered and Portable Equipment

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781/329-4700

World Wide Web Site: http://www.analog.com

Fax: 781/326-8703

© Analog Devices, Inc., 1999

PRODUCT DESCRIPTION

The AD620 is a low cost, high accuracy instrumentation ampli-

fier that requires only one external resistor to set gains of 1 to

0

5

10

15

20

30,000

5,000

10,000

15,000

20,000

25,000

0

SUPPLY CURRENT – mA

AD620A

3 OP-AMP

IN-AMP

(3 OP-07s)

Figure 1. Three Op Amp IA Designs vs. AD620

SOURCE RESISTANCE –

100M

10k

1k

10M

1M

100k

10,000

0.1

100

1,000

10

1

TYPICAL STANDARD

BIPOLAR INPUT

IN-AMP

AD620 SUPER ETA

BIPOLAR INPUT

IN-AMP

G = 100

Figure 2. Total Voltage Noise vs. Source Resistance

1000. Furthermore, the AD620 features 8-lead SOIC and DIP

packaging that is smaller than discrete designs, and offers lower

power (only 1.3 mA max supply current), making it a good fit

for battery powered, portable (or remote) applications.

The AD620, with its high accuracy of 40 ppm maximum

nonlinearity, low offset voltage of 50

µV max and offset drift of

0.6

µV/°C max, is ideal for use in precision data acquisition

systems, such as weigh scales and transducer interfaces. Fur-

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

of the AD620 make it well suited for medical applications such

as ECG and noninvasive blood pressure monitors.

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

the use of Super

βeta processing in the input stage. The AD620

works well as a preamplifier due to its low input voltage noise of

9 nV/

√Hz at 1 kHz, 0.28 µV p-p in the 0.1 Hz to 10 Hz band,

0.1 pA/

√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.