Multi-Objective Optimum Design of DMS Filters Using Robust Engineering and Genetic Algorithm

A robust multi-objective optimization technique for the structural design of double mode surface acoustic wave (DMS) filters is proposed. The frequency response characteristics of DMS filters are governed primarily by their geometrical structures: the configurations of interdigital transducers (IDTs) and grating reflectors fabricated on piezoelectric substrates. For deciding suitable structures of DMS filters based on the computer simulation, the equivalent circuit models of IDT and grating reflector, which include several uncertain constant parameters, are usually used. In order to cope well with the designing imperfections caused by the inevitable dispersion of these constant parameters, the robust engineering, or the Taguchi method, is employed to evaluate the robustness of DMS filters. Then, because there is a trade-off relationship between the robustness of DMS filters and their ideal functions, the robust optimum design of DMS filters is formulated as a multi-objective optimization problem. Furthermore, an efficient multi-objective evolutionary algorithm, or revised NSGA-II, is used to obtain a set of Pareto-optimal solutions of the problem.