Investigation on Third-Order Intermodulation Distortions Due to Material Nonlinearities in TC-SAW Devices

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 65; no. 10; pp. 1914 - 1924
• Main Authors: Chauhan, Vikrant, Mayer, Markus, Mayer, Elena, Ruile, Werner, Ebner, Thomas, Bleyl, Ingo, Wagner, Karl C., Weigel, Robert, Mayer, Andreas P., Hagelauer, Amelie
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.10.2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Computer simulation; Data models; Devices; Electrodes; Finite element analysis; Finite element method; Frequency measurement; Geometrical and material nonlinearity; Intermodulation; Lithium niobates; Mathematical models; Metallization; Metallizing; Nonlinear programming; Nonlinearity; Perturbation methods; Perturbation theory; Piezoelectricity; Scaling factors; Silicon dioxide; Simulation; Substrates; Surface acoustic wave devices; Surface acoustic waves; temperature compensated surface acoustic wave (SAW); third-order intermodulation products
• ISSN: 0885-3010; 1525-8955; 1525-8955
• DOI: 10.1109/TUFFC.2018.2832283

Nonlinearity can give rise to intermodulation distortions in surface acoustic wave (SAW) devices operating at high input power levels. To understand such undesired effects, a finite element method (FEM) simulation model in combination with a perturbation theory is applied to find out the role of different materials and higher order nonlinear tensor data for the nonlinearities in such acoustic devices. At high power, the SAW devices containing metal, piezoelectric substrate, and temperature compensating (TC) layers are subject to complicated geometrical, material, and other nonlinearities. In this paper, third-order nonlinearities in TC-SAW devices are investigated. The materials used are LiNbO 3 -rot128YX as the substrate and copper electrodes covered with a SiO 2 film as the TC layer. An effective nonlinearity constant for a given system is determined by comparison of nonlinear P-matrix simulations to third-order intermodulation measurements of test filters in a first step. By employing these constants from different systems, i.e., different metallization ratios, in nonlinear periodic P-matrix simulations, a direct comparison to nonlinear periodic FEM-simulations yields scaling factors for the materials used. Thus, the contribution of the different materials to the nonlinear behavior of TC-SAW devices is obtained and the role of metal electrodes, substrate, and TC film are discussed in detail.