Design of infinite impulse response (IIR) bandpass filter structure using particle swarm optimization

This article presents the application of particle swarm optimization (PSO) algorithm for the design of infinite impulse response (IIR) bandpass digital filter. Bilinear transform (BLT) design method was first used as baseline method to compute the filters’ approximate transfer functions based on conversion of the analog filter’s transfer function from the s-plane to the equivalent digital filter transfer function in z-plane. The filter transfer function was obtained from the BLT design based on the given specifications. PSO algorithm was also used to generate the optimal filter coefficients for the same specifications. A population of 20 particles was initialized to probe the search space. The particles’ performance was evaluated by the fitness function defined as the mean square error between the magnitude of the designed filter and the magnitude of the desired (ideal) filter. The particle’s velocity and position in the search space are adjusted according to the PSO equations. The response of the PSO designed filter was compared with the response of BLT designed filter. Simulation results show close performance of both filters in discriminating a multi-frequency input signal.