Film bulk acoustic resonator finite element model in active filter design

Abstract

Film bulk acoustic resonators (FBARs) are becoming increasingly requested as an element of high-performance bandpass filters for modern microwave communication systems due to its inherent advantages at high frequencies. Active filter design using FBAR allows realizing of a wider range of characteristics. The FBAR active filter design process is related with the optimization of multiple parameters including filter architecture, biasing of active elements, impedance matching and also the topology and structure of resonators. Obtaining of filter's frequency characteristics with high selectivity and smooth phase response is only possible using high-precision models of resonators. The purpose of this work is to propose a three-dimensional finite element model (FEM) of a FBAR for further integration into the computer-aided filter design system. The simulation results of the proposed solution are compared with a frequently used modified Butterworth-Van-Dyke (mBVD) model to designate the significance of changes in the output filter characteristics arising from the application of 3D piezoelectric resonator model.