Two-Dimensional Coupling-of-Modes Model for Surface Acoustic Wave Devices Considering Power Flow Angle

Abstract

A new form of two-dimensional coupling-of-modes (2D-COM) equations considering power flow angle was proposed and verified experimentally. By adopting a wave vector relationship in elliptic approximation form, the parabolic 2D-COM equations were improved into an elliptic form which is applicable to the simulation of surface acoustic wave resonators considering power flow angle (PFA-SAWR). Combined the method with COMSOL PDE module, a complete simulation model for PFA-SAWR’s frequency response was established. Take the periodic grating structure on the AT-22° quartz substrate (PFA ≈5.4°) as an example, a case analysis was carried out based on this new simulation model. The accuracy of the model was confirmed by comparing the results of 3D FEM analysis. Then, in the experiment part, a PFA-SAWR on the AT-22° quartz substrate was fabricated and measured, the frequency responses obtained by simulation and experiments are in good agreement. Finally, a new resonator structure which can effectively suppress the transverse modes and improve the Q value of resonators was introduced. This new simulation model provides an effective technique for accurately analyzing and designing PFA-SAWRs.