IIR M-th band filters with allpass components
In this paper, we propose a new allpass-based structure for the IIR M-th and 2M-th band filters. These filters consist of M allpass filters, and an interpolation filter (sum of two allpasses). Consequently, the proposed structure is very efficient in implementation. By choosing the allpass phase appropriately the resulting phase response of the IIR M-th band filter is approximately linear. An example is designed and compared with FIR M-th band filters.