Patent ID: 8717121

Claim:
A bulk acoustic wave resonator comprising: a substrate; a resonator section in which a piezoelectric film is sandwiched between a pair of electrodes and a vibration region is defined, the vibration region being an area where the electrodes overlap with the piezoelectric film disposed therebetween when viewed from a film thickness direction; a support section that is elastically deformable, connects the substrate and the resonator section in a state in which one of the electrodes of the resonator section faces a principle surface of the substrate, and allows the one of the electrodes of the resonator section to move toward and away from the principle surface of the substrate; a membrane arranged between the one of the electrodes of the resonator section and the principle surface of the substrate, the membrane facing the vibration region of the resonator section and being fixed on the substrate so as to be spaced away from the principle surface of the substrate; and driver sections arranged on the resonator section and the substrate adjacent to the vibration region and the membrane, respectively, the driver sections allowing the resonator section to move relative to the substrate such that the one of the electrodes of the resonator section moves toward and away from the principle surface of the substrate; wherein the vibration region of the resonator section contacts the membrane when the driver sections move the one of the electrodes of the resonator section close to the principle surface of the substrate, and the vibration region of the resonator section separates from the membrane when the driver sections move the one of the electrodes of the resonator section away from the principle surface of the substrate.