Behaviors of higher-order modes in I.H.P. SAW devices and discussion of their suppression

Abstract

In this work, behaviors of higher-order modes in an I.H.P. SAW device with a layered LiTaO3/SiO2/SiN/Si substrate are investigated, and suppression techniques of them are discussed. First, variation of the higher-order mode responses with structural parameters are analyzed using two-dimensional FEM. Then, on the basis of the calculated data, structural parameters for higher-order modes suppression with keeping main mode characteristics are determined. In addition, effectiveness of the optimized structure is confirmed from the measured data of fabricated a one-port resonator and filters. In measured data, it is shown that higher-order modes in a specific frequency range are successfully suppressed, while main made characteristics such as Bode-Q, bandwidth, and TCF are almost equivalent with those of the conventional I.H.P. SAW resonators and filters.