A Study of the Effects of Apodized Structure Geometries on SAW Filter Parameters

Apodization is the most common- ly used weighting technique for defining the impulse response of SAW filters. This work presents the results and compares the parameters of six of the most commonly used transducer apodization geometries. Parameters are presented for the six apodization implementations of a low shape factor filter design example. The parame- ters compared are apodization loss, frequency dependent transducer acoustic conductance and susceptance, transducer group delay and filter passband response. Fast and efficient track modeling ap- proaches are presented. The results show the importance of anticipating the effects of structure geometry when designing apodized low loss SAW filters. Results of the modeling are verified for the case of a low shape factor slant centered apodized transducer SAW filter.