Differential Amplifier

Differential amplifiers are used mainly to suppress noise. Noise consists of typical differential noise and common-mode noise, of which the latter can easily be suppressed with an op-amp. There are two main causes of common-mode noise: -Noise is generated in the wires and cables, due to electromagnetic induction, etc., and it causes a difference in potential (i.e., noise) between the signal source ground and the circuit ground. -Current flowing into the ground of a circuit from another circuit causes a ground potential rise (noise).