M-channel approximately linear phase IIR filters using allpass subfilters
A new M-channel IIR filter bank design method is presented where IIR filters are obtained from allpass subfilters and a modulation block. Allpass filters are designed by using the eigenfilter method to obtain approximately linear phase response. The combination of allpass filters is determined by the modulation block which is important for obtaining good IIR filters. In this paper, unitary and nonunitary, real modulation blocks are discussed and examples are designed and compared. In addition a general methodology for polyphase representation of an IIR filter is presented. By this approach it is shown that IIR QMF Banks can be implemented in polyphase form which is computationally more efficient than the direct form implementation in general. Furthermore the analysis of QMF bank structure is simpler in the polyphase representation.<<ETX>>