基片表面力负载对saw谐振器特性影响研究-study on the influence of substrate surface force load on saw resonator characteristics.docx

ABSTRACTSurface acoustic wave (SAW) propagates on piezoelectric substrate surface，when the surrounding physical parameters (such as temperature, pressure, magnetic field, electric field, gas, etc.) change the physical characteristics of piezoelectric substrate and consequently the SAW propagation characteristics (such as velocity and loss) will be changed. In order to study the characteristics of SAW resonator under force loaded on the substrate surface, the theoretical analysis and experimental studies areconducted.This paper mainly includes the following aspects:① This paper first introduces the development of SAW technology, the classification and characteristics of SAW devices. Then it elaborates the development, classification, and characteristics of SAW sensors. Finally the physical configuration and sensing mechanism of one-port SAW resonator are analyzed.② Starting from the constitutive equation and motion equation of piezoelectriccrystal, the SAW velocity is calculated by traditional Green function in free state, based on the piezoelectric coupling wave equation of the piezoelectric medium in free state. When force is exerted on the surface of the piezoelectric substrate, the elastic, piezoelectric and dielectric constants of the piezoelectric substrate will change, so the effective material coefficients are a function of the force. The piezoelectric coupling wave equation with force loaded on the substrate surface is deduced. Based on the general Greens function and the piezoelectric coupling wave equation with mechanical loading, SAW velocity with mechanical loading is deduced. With the formula of resonant frequencies, the variation relationship between the exerted force and resonant frequency of SAW resonator is obtained.③ Through a force transfer mechanism, mass blocks are applied on the substratesurface, and generate forces along the directions either perpendicular to or parallel to SAW propagation direction. The resonant frequencies and loss