Patent ID: 8508315

Claim:
A coupled resonator filter, comprising: a first film bulk acoustic resonator (FBAR), having a first electrical impedance and a first resonance frequency, the first FBAR comprising: a first electrode, a first piezoelectric layer having a first thickness, disposed on the first electrode, and a second electrode disposed on the first piezoelectric layer; a second FBAR, having a second electrical impedance and a second resonance frequency, and being disposed over the first FBAR, the second FBAR comprising: a third electrode, a second piezoelectric layer having a second thickness, disposed on the third electrode, and a fourth electrode disposed on the second piezoelectric layer; and a a coupling layer disposed between the first and the second FBARs, wherein the first thickness of the first piezoelectric layer is substantially the same as the second thickness of the second piezoelectric layer, wherein the first and second resonance frequencies are substantially different from each other, and wherein a thickness of the fourth electrode is substantially different than a thickness of at least one of the first, second, and third electrodes.