Patent ID: 8049395
Filing Date: 2011-11-01
Classification: H03H

Abstract:
1. A boundary acoustic wave device comprising: a piezoelectric layer; a dielectric layer laminated on the piezoelectric layer; an IDT electrode arranged at an interface between the piezoelectric layer and the dielectric layer; and a low thermal expansion medium layer laminated on a surface of the piezoelectric layer opposite to the interface and made of a material having a linear thermal expansion coefficient less than that of the piezoelectric layer; wherein the boundary acoustic wave device has a structure the propagates a SH boundary acoustic wave at the boundary between the piezoelectric layer and the dielectric layer; and an acoustic velocity of a SH wave at the piezoelectric layer satisfies Expression (1), and when λ represents a wavelength of the IDT electrode, (an acoustic velocity of a transverse wave at the dielectric layer)/λ with respect to a response frequency of the SH boundary acoustic wave and to a response frequency in a high order mode satisfies Expression (2) as follows: