Piezoelectric filter, communication device, and method for manufacturing communication device

摘要

A piezoelectric filter includes a plurality of piezoelectric resonator portions each having a substrate, an SiO2 layer, a piezoelectric thin-film, a lower electrode, and an upper electrode. The plurality of piezoelectric resonator portions include piezoelectric resonator portions having a relatively low frequency, and the lower electrodes of the piezoelectric resonator portions having a relatively low frequency have a thickness larger than that of lower electrodes of other piezoelectric resonator portions. A ladder-type piezoelectric filter, which is one of the communication devices, includes a plurality of parallel resonators and series resonators.