A Spectral Factorization Approach to Pseudo-QMF Design

A new approach to the design of M-channel pseudo-quadrature-mirror-filter (QMF) banks is presented. In this approach, the prototype filter is obtained as a spectral factor of a 2Mth band filter. This completely eliminates the need for optimization whereas in conventional pseudo-QMF designs, the main computational effort is in optimization of the prototype. As in the conventional approach, the aliasing cancellation (AC) constraint ensures that all the significant aliasing terms are canceled. The overall transfer function T(z) of the analysis/synthesis system has a linear phase and an approximately 'flat' magnitude response in the frequency region epsilon less than or approximate to omega less than or approximate to ( pi - epsilon ), were epsilon depends on the transition bandwidth of the prototype and 0 < epsilon < ( pi /2M). Three design examples are included.