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Noise suppression method for wave filter

  • US 7,057,476 B2
  • Filed: 05/25/2004
  • Issued: 06/06/2006
  • Est. Priority Date: 12/30/2003
  • Status: Active Grant
First Claim
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1. A noise suppression method for a wave filter, the wave filter being provided with at least one film bulk acoustic resonator (FBAR), a piezoelectric film being located at the center of the FBAR, the piezoelectric film having an upper surface and a lower surface, said upper and lower surfaces being plated with conductive material to be used as an upper working electrode and a lower working electrode, respectively, wherein a region overlapping the piezoelectric film and the upper and lower working electrodes forms an acoustic resonant cavity, the noise suppression method comprising at least the following steps of:

  • selecting the region overlapping the piezoelectric film and the upper and lower working electrodes in the structure of the FBAR; and

    providing a plurality of noise scatterers in the structure embodied by the region, wherein said noise scatterers are filled with material that increases a material characteristic difference and a cross section of the scatters is of a random geometrical shape.

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