MEMS and sensors

In very small MEMS accelerometers and gyroscopes, which noise, caused by the proof mass jiggling randomly through thermal interaction with surrounding gas molecules and the like, is one limit on resolution?

  1. AThermomechanical noise (Brownian noise)
  2. BClock noise
  3. CQuantization noise
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Answer: A. Thermomechanical noise (Brownian noise)

At any finite temperature, the proof mass constantly jiggles randomly, for example from collisions with gas molecules. This thermomechanical (Brownian) noise grows as the mass gets lighter and as damping increases (lower Q), and it is a fundamental resolution limit for MEMS sensors.

  • A. Correct. It is noise from thermally driven mechanical motion.
  • B. Clock noise is not a fundamental limit of the sensor's mechanical part.
  • C. Quantization noise arises in AD conversion.
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