Patent ID: 7148604

Claim:
A piezoelectric resonator comprising: a first transducer connected to a first signal terminal; and a second transducer connected to a second signal terminal, wherein the first transducer and the second transducer are stacked in a predetermined direction, wherein the second transducer outputs a signal of a predetermined resonance frequency from a bulk acoustic wave excited in the first transducer and propagating in the predetermined direction inside a piezoelectric film, wherein the second transducer has a first piezoelectric film and a second piezoelectric film which are provided in order in the predetermined direction, the first piezoelectric film being sandwiched between a pair of electrode films on both sides in the predetermined direction, the second piezoelectric film being comprised of a film type different from that of the first piezoelectric film and being sandwiched between a pair of electrode films on both sides in the predetermined direction, and wherein the electrode film more distant from the second piezoelectric film out of the pair of electrode films between which the first piezoelectric film is sandwiched, and the electrode film more distant from the first piezoelectric film out of the pair of electrode films between which the second piezoelectric film is sandwiched, are connected to the second signal terminal.