Filter using piezoelectric resonator

摘要

A series piezoelectric resonator (11) is connected in series between an input terminal (15a) and an output terminal (15b). A first electrode of a first parallel piezoelectric resonator (12a) is connected to a connection point between the input terminal (15a) and the series piezoelectric resonator (11), and a second electrode of the first parallel piezoelectric resonator (12a) is connected to a first terminal of a first inductor (13a). A first electrode of a a second parallel piezoelectric resonator (12b) is connected to a connection point between the series piezoelectric resonator (11) and the output terminal (15b), and a second electrode of the second parallel piezoelectric resonator (12b) is connected to a first terminal of a second inductor (13b). Second terminals of the inductors (13a,13b) are grounded. An additional piezoelectric resonator (14) is connected between the second electrode of the first parallel piezoelectric resonator (12a) and the second electrode of the second parallel piezoelectric resonator (12b).