Using Crossed IDTs to Suppress Transverse Modes in SAW Resonators Based on POI Substrate
Yidan Yin, Wei Jiang, W.F. Huang, Anming Gao
Abstract
In this paper, two types of novel IDT structures are proposed to suppress transverse modes in radio frequency (RF) surface acoustic wave (SAW) resonators based on piezo on insulator (POI) wafer. Finite Element Analysis (FEA) simulations show that both the type I and type II crossed IDTs suppress the transverse modes as they modify the boundary conditions in the transverse direction. The two types of novel crossed IDTs are fabricated and measured as well as conventional IDTs. Compared to other suppression methods, the two novel IDT structures have little effects on the quality factor <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(Q)$</tex> and the effective electromechanical coupling coefficient <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(k^{2})$</tex> of the devices. In addition, type II crossed IDTs structure improves the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$Q_{p}$</tex> of the resonators and is demonstrated by experiments, which is very promising in the application of low-loss 5G front-ends.