Sezawa Mode Enhancement of SAW Resonators on GaN-on-insulator by Optimizing the Metal Thickness and its Application to RF Filters

We present a 700-MHz single-mode SAW resonator on the unreleased GaN-on-sapphire platform. Contrary to the fact about conventional Rayleigh-mode SAW resonators, we observe an optimum metal thickness for our Sezawa-mode-based resonator and obtain a maximum Q factor of 471. In addition, a 700-MHz band-pass filter (BPF) consisting of four proposed SAW resonators is designed and simulated. An insertion loss of 5.2dB, side-band suppression of 22.8dB, relative 3-dB bandwidth of 0.23%, and a size of 0.018 lambda(2)(RF) are obtained.