Patent ID: 7554427

Claim:
A thin film bulk acoustic wave resonator structure comprising: a substrate; at least one acoustic reflection layer; a plurality of thin film bulk acoustic wave resonators stacked with the acoustic reflection layer in-between and disposed over the substrate; an input terminal; and an output terminal, wherein each of the thin film bulk acoustic wave resonators has a piezoelectric layer and a pair of electrodes stacked with the piezoelectric layer in-between, wherein the acoustic reflection layer is electroconductive, and two of the thin film bulk acoustic wave resonators stacked with the acoustic reflection layer in-between are electrically connected via the acoustic reflection layer, wherein at least one of the thin film bulk acoustic wave resonators is electrically connected between the input terminal and the output terminal via the acoustic reflection layer, and wherein the acoustic reflection layer is a Bragg reflection layer which includes a combination of a high-impedance metal layer and a low-impedance metal layer.