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, geometry design, as well as, the selection of
fabrication techniques for their characterization and validation
process. Here, we use the finite element method in COMSOL Multiphysics
to present a methodology and a detailed analysis of the design of a SAW
transducer in a delay line configuration. First, we simulate
single-finger and double-finger configurations of IDTs on LiNbO3 in
64°YX and LiNbO3 128°YX orientation, with the objective of 1) comparing
the simulation results with the analytical delta model to validate the
simulation process, presenting Pearson correlation values ranging from
0. 76 to 0.84. 2) calculate a maximum frequency value obtainable for
those configurations from a resolution of 5 microns in the
photolithography technique, used for the fabrication of SAW transducers.
Next, we extended the analysis to study a specific transducer design
made to operate at a resonant frequency of 97 MHz. In order to determine
the influence of piezoelectric material and IDT configuration we
compared identical designs on 128°YX and 64°YX orientations of LiNbO3
with single and double finger configurations and adding the SPUDT
configuration. We observed the best results for the single-finger IDT
configuration in 128°YX LiNbO3 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 119.59 dB/MHz. The results obtained can serve as a
guide for new researchers or students to expand the use of numerical
tools in the design of SAW transducers and SAW devices.