Patent ID: 9071224
Filing Date: 2015-06-30
Classification: H03H

Abstract:
1. A filter comprising: a plurality of piezoelectric thin film resonators, each having a multilayered film including a lower electrode located on a substrate, a piezoelectric film located on the lower electrode, and an upper electrode located on the piezoelectric film so as to face the lower electrode, wherein at least two piezoelectric thin film resonators each have a thick film portion in at least a part of an outer peripheral portion of a resonance region, the thick film portion being absent in an inner area of the resonance region that is surrounded by said outer peripheral portion, and the multilayered film in the thick film portion is thicker than the multilayered film in any other areas in the resonance region, the resonance region being defined as a region where the lower electrode and the upper electrode face each other across the piezoelectric film for each of said at least two piezoelectric thin film resonators, and respective lengths of the thick film portions from edges of the resonance regions are different from each other in the at least two piezoelectric thin film resonators.