Large Coupling Surface Acoustic Wave Resonator Based On SiO2/5 degrees Y-X LiNbO3 Structure

This paper proposes a temperature-compensated surface acoustic wave (TC-SAW) resonator structure with a large electro-mechanical coupling coefficient (K2). Firstly, the effect of rotating Y-cut LiNbO3 on the K2 of shear-horizontal (SH) mode based on the SiO2/LiNbO3 structure is studied and it indicates that this structure has the largest K2 of 15% when the rotation angle(.) is 5 degrees. We also found a spurious response near the main resonance, which is caused by the Rayleigh-mode and will deteriorate the performance of the filters consisting of these resonators. In this paper, we modeled the TC-SAW resonator structure by COMSOL Multiphysics and analyzed the influence of various structural parameters on the Rayleigh mode. Suppression of spurious responses is successfully achieved by reasonably adjusting various parameters. Finally, a bandpass filter with a relative bandwidth exceeding 8% was designed with these resonators.