Numerical Analysis and Design of a High-Frequency Surface Acoustic Wave Transducer: Influence of Piezoelectric Substrates and IDTs Configurations

Abstract

The development of SAW transducers requires a series of steps ranging from material selection and geometry design to the selection of fabrication techniques for their characterization and validation process. Here, we use the finite element method (FEM) to present a methodology and a detailed analysis of the design of SAW transducers in a delay line configuration. First, we simulate single-finger and double-finger configurations with different geometries and designs of IDTs on two piezoelectric substrates, LiNbO${}_3$ in 64${}^{°}$ YX and LiNbO${}_3$ 128${}^{°}$ YX orientation, to compare the simulation results with the analytical delta model and thereby validate the simulation process, presenting Root Mean Square Error (RMSE) values ranging from 10.79 dB to 16.42 dB. With the above, we performed a comparative analysis to determine the influence of piezoelectric material and IDT configuration by studying a specific transducer design made to operate at a resonance frequency of 97.02 MHz. We compared identical designs on 128${}^{°}$ YX and 64${}^{°}$ YX orientations of LiNbO${}_3$ with single and double-finger configurations and added the comparison with the SPUDT configuration. We observed the best results for the single-finger IDT configuration in 128${}^{°}$ YX LiNbO${}_3$ orientation compared to the other variants through its insertion loss level of −7.29 dB, its average sidelobe level of −18.63 dB, and its average transition band slope for the main lobe of 15.09 dB/MHz. The results guide new researchers or students in expanding the use of numerical tools in designing SAW transducers and SAW devices.