Patent ID: 7636027

Claim:
A piezoelectric resonator comprising: a substrate; a pair of conductive layers disposed on the substrate; and a piezoelectric layer disposed between the pair of conductive layers, wherein the piezoelectric layer disposed between the pair of conductive layers is acoustically isolated from the substrate to form a vibrating region, the vibrating region when viewed in a thickness direction of the pair of conductive layers and the piezoelectric layer has a substantial polygon shape, the sides of which are not parallel to each other, and the vibrating region includes a peripheral portion extending along outer edges of the substantial polygon shape and a central portion inside the peripheral portion, the central portion having a larger thickness than the peripheral portion, wherein the vibrating region is shaped so as to suppress a first spurious Lamb wave having a wavelength that is equal to or less than twice a thickness of the piezoelectric layer, and the thicknesses of the peripheral portion and the central portion are configured to suppress a second spurious Lamb wave having a wavelength that is five or more times the thickness of the piezoelectric layer.