Stability of IIR digital filters constructed with the time-domain pipelining technique

Previously, z-domain or scattered lookahead pipelined IIR filters were thought to offer reduced computational complexity when compared to time-domain or clustered look-ahead IIR pipelined filters. However, the minimum-order augmentation technique provided improved computational complexity by minimizing superfluous poles, at the expense of increased transfer function denominator multipliers. In this paper, we show that for many realizations there exist stable time-domain pipelined IIR filters with computational complexity far less than the z-domain pipelined IIR filters. The decreased complexity in time-domain pipelined IIR filters results from the occurrence of "stability pockets" which allow stable pipeline IIR filters with far fewer superfluous poles than predicted by the stability analyses previously performed.