| abstract |
An apparatus such as a thin film resonator has a bottom electrode, a top electrode, and a composite layer between the two electrodes. The composite layer includes a piezoelectric (PZ) layer having a first coupling coefficient and a coupling coefficient control (CCC) layer having a second coupling coefficient. By varying the relative thicknesses of the PZ layer and the CCC layer during the manufacturing process, the coupling coefficient of the resonator can be established (to any value between the first coupling coefficient and the second coupling coefficient) with minimal impact on resonant frequency. Further, it is relatively less difficult to fabricate the PZ layer and the CCC layer having the desired coupling coefficient (as a combination of the first coupling coefficient and the second coupling coefficient) compared to the difficulties of fabrication of a uniform PZ layer having the desired coupling coefficient. |