MEMS and sensors

Which device uses acoustic waves traveling along the surface of a piezoelectric substrate and serves as a high-frequency filter in smartphones and similar?

  1. ALCD panel
  2. BDRAM cell
  3. CSAW (surface acoustic wave) filter
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Answer: C. SAW (surface acoustic wave) filter

A SAW filter forms comb-shaped electrodes on the surface of a piezoelectric substrate such as lithium tantalate, converts electrical signals into acoustic waves traveling along the surface, and passes only specific frequencies. Being small with good characteristics, SAW filters are used in huge numbers as RF filters in mobile phones. At higher frequencies, BAW filters are used.

  • A. An LCD panel is a display.
  • B. A DRAM cell is a memory element.
  • C. Correct. It is a filter using surface acoustic waves.
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