Optimization of the SAW filter design by immune algorithm

It is effective to use an optimization program to design SAW filter IDTs, aiming at improvement in the filter characteristics and shortening of the lead time of the product design. In general, it is difficult to apply gradient methods such as the Newton-Raphson method because there are a lot of semi-optimal solutions in the allowable range of the design parameters. On such a problem, a heuristics procedure that can carry out a multipoint search is useful. The well known genetic algorithm (GA) is typical of one of these methods. In this paper, the immune algorithm (IA), which is also one of the heuristics, was applied. IA models the immunity mechanism and has the feature of being hard to be trapped in a partial solution as compared with GA. An example of design optimization using IA on a transversal SAW filter is reported.