Analog Devices AD620 - Manual
The AD620 instrumentation amplifier is a low-cost, precision device designed for high-performance signal conditioning across applications like medical instrumentation and data acquisition systems. This manual covers its electrical specifications–including gain range, noise performance, power supply requirements, and temperature stability–along with practical design considerations such as grounding techniques, bias current handling, and RF interference mitigation. Performance graphs illustrate key characteristics like frequency response, output swing limits, and common-mode rejection, while application examples demonstrate its use in pressure monitoring and ECG circuits. The document also addresses packaging details, ESD sensitivity, and comparison benchmarks against alternative designs.
Table of Contents:
- Page 1 – AD620 Instrumentation Amplifier Overview and Applications
- Page 2 – Electrical Specifications for AD620 Variants
- Page 3 – AD620 Variant Electrical Specifications
- Page 4 – AD620 Absolute Ratings and Physical Dimensions
- Page 5 – Typical Electrical Characteristics and Temperature Effects
- Page 6 – Noise and Drift Performance Characteristics
- Page 7 – Key Performance Graphs of the Amplifier
- Page 8 – Signal Response and Settling Time Performance
- Page 9 – Gain Nonlinearity and Pulse Response Analysis
- Page 10 – AD620 Internal Operation and Precision Design
- Page 11 – Comparison with Homebrew Circuit Design
- Page 12 – Applications in Pressure and ECG Monitoring
- Page 13 – Precision V-I Converter Operation Details
- Page 14 – Common-Mode Rejection Optimization
- Page 15 – Ground Return Handling for Input Bias Currents
- Page 16 – AD620 Package Dimensions
CONNECTION DIAGRAM
8-Lead Plastic Mini-DIP (N), Cerdip (Q)
and SOIC (R) Packages
–IN
R
G
–V
S
+IN
R
G
+V
S
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 (
6
2.3 V to
6
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
m
V max, Input Offset Voltage
0.6
m
V/
8
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
m
V p-p Noise (0.1 Hz to 10 Hz)
EXCELLENT AC SPECIFICATIONS
120 kHz Bandwidth (G = 100)
15
m
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
TOTAL ERROR, PPM OF FULL SCALE
SUPPLY CURRENT – mA
AD620A
R
G
3 OP-AMP
IN-AMP
(3 OP-07s)
Figure 1. Three Op Amp IA Designs vs. AD620
SOURCE RESISTANCE –
V
100M
10k
1k
10M
1M
100k
10,000
0.1
100
1,000
10
1
RTI VOLTAGE NOISE
(0.1 – 10Hz) –
m
V p-p
TYPICAL STANDARD
BIPOLAR INPUT
IN-AMP
AD620 SUPER
b
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
µ
V max and offset drift of
0.6
µ
V/
°
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
β
eta 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
µ
V 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
µ
s to
0.01% and its cost is low enough to enable designs with one in-
amp per channel.
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About this manual
- Brand
- Analog Devices
- Model
- AD620
- Document type
- Manual
- Language(s)
- English
- Pages
- 16
- File size
- 571.3 KB
- Format
Summary
Description of the AD620 instrumentation amplifier, its features like gain adjustment, power supply range, low power consumption, performance graphs, and typical applications in medical instrumentation and data acquisition systems.
Performance data including gain range, voltage offset, input bias current, input impedance, output swing, and these values across various conditions for the AD620A, AD620B, and AD620S models.
Electrical specifications including dynamic response, noise characteristics, reference input parameters, power supply requirements, and operating temperature range for the AD620 variants.
