Patent ID: 8264299
Filing Date: 2012-09-11
Classification: H03H

Abstract:
1. A boundary acoustic waves device comprising: a piezoelectric substrate having piezoelectricity; an interdigitated electrode formed on the piezoelectric substrate; a first medium formed on the piezoelectric substrate so as to cover the interdigitated electrode; and a second medium formed on the first medium, the interdigitated electrode having a plurality of electrode fingers and a bus bar that connects ends of the plurality of electrode fingers, wherein the boundary acoustic waves device includes a third medium formed on the first medium, the second medium and the third medium are in contact with the first medium, the first medium, the second medium, and the third medium respectively are formed of different materials, and a ratio in length of a part with the third medium formed with respect to a length of a propagation path of boundary acoustic waves in a cross-section perpendicular to a longitudinal direction of the electrode fingers varies in the longitudinal direction of the electrode fingers, wherein the first medium is divided into halves in a direction perpendicular to the longitudinal direction of the electrode fingers, as a region on which the third medium is formed and a region on which the third medium is not formed, and wherein the third medium is formed of at least two media that are formed of different materials.