Abstract
An optimal design approach for Surface Acoustic Wave (SAW) filters is presented. The frequency response characteristics of SAW filters are governed primarily by their geometrical structures, i.e., the configurations of respective interdigital transducers (IDTs) arranged on piezoelectric substrates. First of all, for realizing a desirable bandpass filter, the structural design of a three-IDT type SAW filter, which consists of three IDTs and two reflectors, is formulated as a combinatorial optimization problem. In order to simulate the frequency response of the SAW filter, the least equivalent circuit model of IDT is employed. Then, a variable neighborhood search based on the k-degree-neighborhood is proposed for solving the optimization problem. Changing the number of examined variables in the process of local search, it avoids being trapped in the first local optimal solution found. Computational experiments conducted on the practical design problem of the three-IDT type SAW filter demonstrate the usefulness of the proposed variable neighborhood search.
