The diff amp is extremely useful as the input stage of an op amp because
A) it has low input impedance.
B) it has a single-ended input.
C) it amplifies the common-mode signal.
D) it attenuates the common-mode signal.

Question

Quizplus · Accepted Answer

The differential amplifier attenuates or rejects the common-mode signal, which is undesirable noise or interference present on both inputs, while amplifying or amplifying the differential signal, which contains the useful information. This is critical in high-precision applications such as instrumentation, where even small amounts of unwanted noise can distort the signal and influence the accuracy of the measurement. Therefore, the diff amp is a useful input stage of an op amp because it allows the op amp to amplify only the differential signal and reject common-mode noise.

The Diff Amp Is Extremely Useful as the Input Stage