MULTIOBJECTIVE OPTIMIZATION OF BAND-PASS FILTERS CHARACTERISTICS USING HEURISTIC ALGORITHM
The problem of multiobjective optimization of band pass filter (BPF) is investigated. There were three objectives considered: a nonuniformity of attenuation in the pass band, a minimum attenuation in the stop band and a nonuniformity of delay time in the pass band. The first method of solution was to derive Pareto-optimal approximations for BPF from such for low pass filter (LPF) by means of reactance frequency transform. The second method was to search optimal approximation for BPF directly. In the both methods the heuristic algorithm was applied. This algorithm searches out the set of Pareto optimal solutions and uses multistart for searching of global extreme for each point of Pareto front. The numerical experiments showed that for cases with wide pass band of BPF and comparatively poor-quality indexes of gain frequency response the second method can give lower nonuniformity of delay time than the first one when other objectives are the same. This result means that Pareto-optimality does not persist in the frequency transform in such cases. At once in the cases with narrow pass band of BPF or comparatively good quality indexes of gain frequency response the direct search provides no preferences.