Patent ID: 7378922

Claim:
A piezoelectric filter comprising: a first substrate having at least one first piezoelectric resonator disposed on a first surface of the first substrate; a second substrate having at least one second piezoelectric resonator disposed on a second surface of the second substrate; a connection pattern extending around the first piezoelectric resonator and the second piezoelectric resonator and disposed between the first substrate and the second substrate, the first surface of the first substrate facing the second surface of the second substrate, and the first piezoelectric resonator being remote from the second piezoelectric resonator; a connecting layer bonding a first pad disposed on the first surface of the first substrate to a second pad disposed on the second surface of the second substrate; and an external electrode connected to the second pad disposed on the second surface of the second substrate, wherein the external electrode is disposed on a third surface of the second substrate, the first piezoelectric resonator and the second piezoelectric resonator are each thin-film piezoelectric resonators having a piezoelectric thin film disposed between a pair of excitation electrodes, and the material of the piezoelectric thin film of the first piezoelectric resonator is different from the material of the piezoelectric thin film of the second piezoelectric resonator.