Design of phase equalizer for rational filter banks using minimax approach

In this paper, we propose both IIR-based and FIR-based all-pass filters based on the minimax criterion. The advantage of this approach over the conventional algorithms is that it incorporates both magnitude and phase constraints, which may be related via Hilbert transform so that we can present a design procedure to find a stable IIR all-pass filter. As a result, one example of numerical design is shown to verify the proposed method. In addition, the FIR-based phase equalizer for reducing the phase distortion caused by rational filter banks is also addressed to demonstrate the usefulness of our approach.