SAW Resonator with Grooves for High Temperature Sensing Application

Wireless passive surface acoustic wave (SAW) resonator has great potential in high temperature sensing applications. Nevertheless, degradation of metal electrodes and decrease of Q factors with rising temperature restrict the temperature upper limit of SAW resonators. From a structural perspective, a SAW resonator structure with grooved electrodes for interdigital transducers and groove-only grating for reflectors is proposed to improve the resonator performance at high temperatures. Quasi-3D periodic FEM models of platinum /trapezoidal-groove/langasite(0°, 22°, 30°) are established and the simulation results show that the grooved electrode is beneficial for electroacoustic coupling factor and pressure sensitivity. In addition, the groove-only grating with no metal reduces the negative effect of high temperature on resonator performance. It has been also verified by coupling-of-model theory that the spurious modes caused by structural difference can be suppressed.