Piezoelectric thin film resonator, filter using the resonator, duplexer using the filter, and communication equipment using the filter or the duplexer

Abstract

There is provided a piezoelectric thin film resonator that decreases only transverse mode waves selectively while maintaining resonance characteristics due to original thickness longitudinal vibration. The piezoelectric thin film resonator includes: a piezoelectric film (14); a first electrode (15a) formed on a first principal surface of the piezoelectric film (14); and a second electrode (13) formed on a second principal surface of the piezoelectric film (14) opposite to the first principal surface. The resonator has a resonance region (20) where the first electrode (15a) and the second electrode (13) are opposed to each other. An electrically discontinuous portion (18a) that is insulated from the first electrode (15a) is provided on the first principal surface of the piezoelectric film (14) in the resonance region (20), and the electrically discontinuous portion (18a) is surrounded by the first electrode (15a) on the first principal surface.

Dependencies are inferred from the claim text.