NEW APPROACH TO CLUSTERED LOOK-AHEAD PIPELINED IIR DIGITAL-FILTERS

Authors Lim and Liu recently introduced the ''minimum order augmentati on'' technique for pipelining IIR digital filters which guarantees the addition of the least number of superfluous poles to obtain a stable pipelined IIR filter while maintaining a ''clustered look-ahead'' pipe line structure. Unfortunately, this minimization of the superfluous po les comes at the expense of adding additional denominator multipliers. In this paper, we introduce a ''minimum order clustered look-ahead'' that achieves the minimum number of superfluous poles possible while m inimizing the total number of multipliers for a ''clustered look-ahead '' pipeline structure. We show that while our new technique does in so me instances require more superfluous poles, the increase in hardware complexity with respect to incremental augmentation is lower when comp ared to the Lim and Liu approach. A MATLAB computer program is describ ed which allows the design of any order pipelined IIR filter. Examples demonstrate that stable ''clustered look-ahead'' pipelined IIR filter s can be designed with the minimum number of superfluous poles (as ach ieved by Lim and Liu), but with fewer denominator multipliers thus red ucing significantly the computational complexity in many cases. Furthe rmore, an analytic solution to the second-order case gives a very prac tical approach to pipelined IIR filter design with great insight into the stability characteristics of pipelined IIR filters.