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AN-1264
APPLICATION NOTE
One Technology Way • P. O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com
Precision Signal Conditioning for High Resolution Industrial Applications
by Gustavo Castro and Kristina Fortunado
Rev. 0 | Page 1 of 8
INTRODUCTION
Industrial measurement and control systems often need to
interface to sensors while operating in noisy environments.
Because sensors typically generate very small electrical signals,
extracting their output from the noise can be challenging.
Applying signal conditioning techniques, such as amplification
and filtering, can aid in the extraction of the signal because
these techniques increase the sensitivity of the system. The
signal can then be scaled and shifted to take full advantage of
high performance ADCs.
This application note introduces a general-purpose precision
signal conditioning front end that can close the gap between
sensors and high resolution ADCs. The circuit is analyzed to
find its noise contribution, ambient noise rejection, and ability
to perform highly sensitive measurements.
Figure 1. Precision Signal Conditioning Circuit Schematic
V
IN+
V
IN–
4.7kΩ
20kΩ
20kΩ
10MΩ
AD8421
V
OUT–
V
OUT+
0.068µF
0.1µF
100pF
1nF
11795-001
IN-AMP AS DIFFERENTIAL FRONT END
FILTER
ADC DRIVER
4.7kΩ
10MΩ
R
G
+15V
–15V
REF
0.1µF
100pF
0.1µF
+15V
–15V
AD8510
33kΩ
0.01µF
+5V
AD8475
0.1µF
10kΩ
10kΩ
ADC_REF
1.25kΩ 1.25kΩ
1.25kΩ 1.25kΩ
1kΩ
1kΩ
0.1µF
