Analog and electronic circuits

Which noise, particularly noticeable in MOSFETs, grows larger at lower frequencies?

  1. A1/f noise (flicker noise)
  2. BShot noise
  3. CThermal noise
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Answer: A. 1/f noise (flicker noise)

1/f noise has a power spectral density inversely proportional to frequency, so it is larger at low frequencies. In MOSFETs it is mainly attributed to traps at the gate insulator interface capturing and releasing carriers, and it tends to be larger than in bipolar transistors. Techniques such as chopper stabilization are used to counter it.

  • A. Correct. 1/f noise is larger at lower frequencies.
  • B. Shot noise is also white noise, independent of frequency.
  • C. Thermal noise is white noise, constant across frequency.
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