Suppression Technique of fast-shear-wave spurious responses in SAW resonators on SiO2/Al/LiNbO3 structure

SH mode on SiO₂/Al/LiNbO₃ structure is studied because of their sufficient electromechanical coupling factor (K²) and good temperature coefficient of frequency (TCF). Authors proposed the suppression method of the spurious response of the Rayleigh mode and the transverse mode for the narrow duplex gap application. For the narrow duplex gap application, SiO₂ thickness must be increased to achieve the good TCF characteristics. However, another spurious response is appeared near the fast-shear-wave as increasing the SiO₂ thickness. This paper discusses the suppression mechanism of the spurious response near the fast-shear-wave.