Direct form-based pipelined IIR filter realization

Pipelining increases throughput of a digital system. It is straightforward to pipeline systems with only feedforward paths. Difficulty arises when we pipeline a system with a feedback loop such as IIR filters. To solve the problem, a look-ahead transformation is applied to the system transfer function. In this paper, we propose a new technique to pipeline recursive filters. By increasing the internal signal rate and distributing the delay unit in the feedback path, a pipelined realization can be achieved without increasing the system latency. Furthermore, by applying the cluster look-ahead transformation to the system transfer function, we can tradeoff between the speed and the number of coefficients in the proposed pipelined structure