应用于无线传感器的声表面波反射型延迟线的耦合模分析

Simulation and design on surface acoustic wave reflective delay line for wireless sensor application using coupling of modes

基于耦合模理论对一种应用于无线传感器的声表面波(SAW)反射型延迟线的性能进行了优化模拟分析。结合混合等效电路模型推导出评价这种器件性能的时域反射系数S_(11)。典型的SAW反射型延迟线包含置于压电基片之上的一个换能器与沿声波传播方向设置的多个反射器。讨论了器件性能的各种结构性影响因素如换能器结构以及反射器类型等,并以此获得优化的器件设计参数。在理论优化分析的基础上,以41°YX LiNbO_3为压电基片,结合铝电极试验制作了采用单向单相换能器(SPUDT)与3个短路栅反射器的440 MHz SAW反射型延迟线器件,并与理论分析结果予以对比与评价分析。

This paper presented an optimal design on surface acoustic wave （SAW） reflective delay line using coupling of modes （COM） and equivalent circuit model, the reflective coefficient S11 of the SAW device was deduced to evaluate the device performance. Typical SAW reflective delay line consists of a piezoelectric substrate, an interdigital tranducer （IDT） and several reflectors positioned along the acoustic propagation direction. The effects of the design parameters of the device as structure of the IDT and reflector types on device performance were investigated, and the optimal design parameters were determined. Based on these parameters, a 440 MHz SAW reflective delay line with single phase unidirectional transducers （SPUDT） and three shorted grating reflectors was fabricated on 41° YX LiNbO3, and the measured Sn agrees well with the simulated one, sharp reflection peaks, high signal noise ratio （SNR）, and low spurious noise between the reflection peaks were observed.