A Spectral Factorization Approach to Pseudo-QMF Design

A new approach to the design of M-channel pseudoquadrature-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 analysidsynthesis system has a linear phase and an approximately “flat” magnitude response in the frequency region E 5 w 5 ( R E), where E depends on the transition bandwidth of the prototype and 0 < E < ( x / 2 M ) . Three design examples are included.