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Article: Avoiding instrumentation amplifier common-mode voltage problems.
- Article from:
- EDN
- Article date:
- June 12, 1996
- Author:
CopyrightCOPYRIGHT 1996 Reed Business Information, Inc. (US). This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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What you see in the manufacturer's specifications may not be what you get. Here's why.
An instrumentation amplifier's common-mode voltage input range, for linear operation, is limited by two factors: 1) The ability of the input stages to linearly track common-mode voltages and 2) the ability to output an appropriate voltage during the presence of a common-mode voltage. It is the second and more commonly overlooked issue that will be discussed here.
Common-mode voltage is usually thought of as one signal which has a difference signal riding on it. A "high-side" shunt (resistor), used for measuring current flow from a battery or power supply might have a small ...