FEATURES
Easy to use
Excellent dc performance (B grade)
Low noise
Excellent ac specifications
APPLICATIONS
Weigh scales
ECG and medical instrumentation
Transducer interface
Data acquisition systems
Industrial process controls
Battery-powered and portable equipment
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.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
Gain set with one external resistor
Wide power supply range (±2.3 V to ±18 V)
Higher performance than 3 op amp IA designs
Available in 8-lead DIP and SOIC packaging
Low power, 1.3 mA max supply current
50 µV max, input offset voltage
0.6 µV/°C max, input offset drift
1.0 nA max, input bias current
100 dB min common-mode rejection ratio (G = 10)
9 nV/√Hz @ 1 kHz, input voltage noise
0.28 µV p-p noise (0.1 Hz to 10 Hz)
120 kHz bandwidth (G = 100)
15 µs settling time to 0.01%
(Gain range 1 to 10,000)
30,000
25,000
20,000
15,000
10,000
5,000
Figure 2. Three Op Amp IA Designs vs. AD620
0
0
R
AD620A
G
5
SUPPLY CURRENT (mA)
10
15
3 OP AMP
(3 OP-07s)
IN-AMP
20
PRODUCT DESCRIPTION
The AD620 is a low cost, high accuracy instrumentation
amplifier that requires only one external resistor to set gains of
1 to 10,000. 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.
Furthermore, 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 Superϐeta 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,
and 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.
Figure 1. 8-Lead PDIP (N), CERDIP (Q), and SOIC (R) Packages
Instrumentation Amplifier
10,000
Figure 3. Total Voltage Noise vs. Source Resistance
1,000
100
0.1
10
1
1k
–V
+IN
–IN
R
CONNECTION DIAGRAM
G
S
1
3
4
2
G = 100
10k
Low Cost Low Power
TYPICAL STANDARD
BIPOLAR INPUT
IN-AMP
TOP VIEW
AD620
SOURCE RESISTANCE ( Ω )
100k
1M
8
6
5
7
AD620 SUPER β ETA
BIPOLAR INPUT
IN-AMP
R
OUTPUT
REF
+V
G
S
10M
100M
AD620