Patent ID: 7479847
Filing Date: 2009-01-20
Classification: H03H

Abstract:
1. A filter comprising: a series piezoelectric resonator part including at least one series piezoelectric resonator having a first electrode and a second electrode, the series piezoelectric resonator being connected in series between an input terminal and an output terminal; a parallel piezoelectric resonator part including at least two parallel piezoelectric resonators each having a first electrode and a second electrode, the parallel piezoelectric resonators being connected, via the first electrodes, in parallel to the series piezoelectric resonator and in a ladder configuration; an inductor part including inductors provided to at least two of the parallel piezoelectric resonators, respectively, the inductors each being connected between a ground and a respective one of the second electrodes of the parallel piezoelectric resonators; and an additional piezoelectric resonator part including at least one additional piezoelectric resonator having a first electrode and a second electrode, the additional piezoelectric resonator being connected between any two second electrodes of the parallel piezoelectric resonators having the inductors connected thereto.