Thickness extensional vibration piezoelectric resonator and piezoelectric resonance device

Abstract

A thickness-extensional piezoelectric resonator using a harmonic of a thickness-extensional vibration mode has a compact size, large electric capacity, is not affected by the stray capacitance of a circuit board, and has small variations in resonance characteristics. The thickness-extensional piezoelectric resonator includes a piezoelectric body, a first excitation electrode, a second excitation electrode, a terminal electrode and a connection electrode disposed on outer surfaces of the piezoelectric body, as well as an internal electrode inside of the piezoelectric body. Portions where the first excitation electrode, the second excitation electrode and the internal electrode overlap define a resonating portion. In the length direction of the piezoelectric body, a vibration-attenuating portion is defined at opposite sides of the resonating portion, whereas in the width direction, the vibration-attenuating portion is not provided at each side thereof. In addition, a relationship of Go/D≧2.0 is satisfied, wherein Go represents a distance between the terminal electrode and the first excitation electrode, D is substantially equal to T/N, and wherein T is the thickness of the piezoelectric body and N is the order of harmonic vibrations.