PIEZOELECTRIC BULK VIBRATOR

摘要

An object of the invention is to provide a piezoelectric bulk acoustic wave device having a high effective electromechanical coupling constant and allowing a fractional bandwidth to be broadened when applied to a filter and a normalized frequency variable width to be broadened when applied to an oscillator. Another object of the invention is to provide a miniature piezoelectric bulk acoustic wave device capable of operating at a high frequency of several hundreds of megahertz while maintaining a high electromechanical coupling constant. The piezoelectric bulk acoustic wave device includes a piezoelectric substrate constructed of a single crystal or oriented crystal body of potassium niobate and having a pair of major surfaces, and at least one pair of opposed electrodes formed on the major surfaces of the piezoelectric substrate, respectively, wherein the device utilizes thickness vibration propagating along the major surfaces. <IMAGE>