Simulation on Effects of Electrical Loading due to Interdigital Transducers in Surface Acoustic Wave Resonator

This paper investigates the effects of electrical loading due to metallic interdigital transducer (IDT) on surface acoustic wave (SAW) velocity in SAW resonators by simulation using FEM in COMSOL Multiphysics. The IDT electrodes fabricated over the piezo-substrate short circuit the parallel electric field associated with SAW under the IDT during wave propagation and affect the SAW phase velocity. The simulation considers a SAW resonator with massless infinite number of IDT fingers on Y–Z cut lithium niobate substrate. The changes in resonance frequency and SAW phase velocity of SAW resonator due to electrical loading are studied for various metallization ratios. The electric field distribution at the surface of piezo-substrate is obtained and it is observed that the short circuit of the electric field due to metallic IDT reduces the SAW phase velocity; consequently, the resonance frequency of the SAW device decreases.