Piezoelectric filter, antenna duplexer, and communications apparatus employing piezoelectric resonator

摘要

A piezoelectric filter comprises a substrate and a plurality of piezoelectric resonators provided on the same substrate. Each piezoelectric resonator comprises a cavity formed in the substrate, a lower electrode formed on the substrate, covering the cavity, a piezoelectric material layer formed on the lower electrode, and an upper electrode formed on the piezoelectric material layer. At least one of the piezoelectric resonators has a cavity formed of a plurality of cells.