Analog and electronic circuits

What does a large CMRR (common-mode rejection ratio) of a differential amplifier mean?

  1. APower consumption is high
  2. BIt is good at rejecting noise that appears equally on both inputs (common-mode signals)
  3. CIts gain is less than 1
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Answer: B. It is good at rejecting noise that appears equally on both inputs (common-mode signals)

Ideally, a differential amplifier amplifies the difference between its two inputs and does not amplify components common to both (common-mode signals). CMRR is the ratio of differential gain to common-mode gain; the larger it is, the more immune the amplifier is to common-mode noise such as power-supply noise and induced noise.

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