The modeling of the transverse mode in TC-SAW using SiO2/LiNbO3 structure

The temperature-compensated surface acoustic waves (TC-SAW) have been developed to fulfill tight roll-off requirements for recent mobile communication systems. Use of the Rayleigh SAW on SiO2-overlay/LiNbO3 substrate structure is one of the most promising techniques for the purpose. Currently, SAW device designs are done entirely through computer simulation, and their accuracy significantly impacts achievable device performance. The coupling of modes (COM) model is widely used for the acoustic simulation and its applicability is well recognized. This paper proposes a simple simulation model based on COM model for the transverse mode behaviors in the TC-SAW devices and applied to the device design. Double mode saw filter and ladder type filter are optimized with the proposed model. Optimized structure is applied to the development of the 1.6 × 1.2 mm2 sized duplexer for LTE Band 8. Smooth passband characteristics with less transverse modes responses are achieved by using the proposed method.