Glossary
Definition
Common-mode signals are identical signal components on both the + and - inputs of a differential amplifier or instrumentation amplifier. A common example is in a balanced pair, where a noise voltage is induced in both conductors. Another example is where
In an ideal differential amp, the common-mode element is cancelled out, since the differential (+ and -) inputs should subtract out the identical components. A measurement of the actual ability to do this is called the Common Mode Rejection Ratio, or CMRR.
