Patent ID: 8058768

Claim:
A bulk acoustic wave, BAW, resonator device comprising first and second metal layers and an intervening piezoelectric layer, the first metal layer comprising spaced first and second portions, wherein the first and second portions are each arranged as a plurality of interconnected fingers, and wherein each of the plurality of fingers of the first portion is acoustically coupled to at least one of the fingers of the second portion, and the second metal layer comprises spaced third and fourth portions, wherein the third and fourth portions are each arranged as a plurality of interconnected fingers, wherein the fingers of the third portion are arranged opposed to the fingers of the first portion and the fingers of the fourth portion are arranged opposed to the fingers of the second portion, wherein the first metal layer comprises a first plurality of further portions arranged to provide acoustic coupling between the fingers of the first portion and the fingers of the second portion, the second metal layer comprises a second plurality of further portions arranged to provide acoustic coupling between the fingers of the third portion and the fingers of the fourth portion, and wherein the first portion is coupled to an input port and the second portion is coupled to an output port.