The Instrumentation Amplifier ICs amplify the difference between two input signal voltages, while rejecting any signals that are common to both inputs. The DC precision and gain accuracy is maintained within a noisy environment, and also where large common-mode signals (AC power line frequency) are present.

Instrumentation Amplifiers, Intersil

Instrumentation Amplifier is a type of differential amplifier that has been outfitted with input buffer amplifiers, which eliminate the need for input impedance matching. Characteristics include very low DC offset, low drift, low noise, very high open-loop gain, very high common-mode rejection ratio, and very high input impedances.