In Situ Analysis and Optimization of SAW Filters

Abstract

The sensitivity of a filter on (YZ) LiNbO3 to in situ perturbations of interdigitated transducer apodization is determined experimentally. From this data an optimal apodization is derived which reduces the filter sidelobe level. Results are shown in which a filter with a single apodized IDT is compensated to reduce sidelobes from -26 to -39 dB. For a filter with two apodized IDTs sidelobes have been reduced from -52 dB to -70 dB.