MEMS and sensors

Which phenomenon do BAW filters, used as RF filters in smartphones and similar devices, use?

  1. AHall effect
  2. BMechanical resonance of a piezoelectric thin film
  3. CSeebeck effect
Show answer and explanation

Answer: B. Mechanical resonance of a piezoelectric thin film

A BAW (bulk acoustic wave) filter uses a resonator in which a piezoelectric thin film such as aluminum nitride is sandwiched between electrodes. An electrical signal makes the film vibrate through its thickness, and its resonance at a specific frequency is used to pass only signals in the needed band.

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