VLSI Digital Signal Processing Systems: Design and Implementation

2.1    INTRODUCTION

Many DSP algorithms such as recursive and adaptive digital filters contain feedback loops, which impose an inherent fundamental lower bound on the achievable iteration or sample period. This bound is referred to as the iteration period bound, or simply the iteration bound. The iteration bound is a characteristic of the representation of an algorithm in the form of a dataflow graph (DFG); different representations of the same algorithm may lead to different iteration bounds. It is not possible to achieve an iteration period less than the iteration bound even when infinite processors are available. This chapter defines the iteration bound and presents two techniques to compute the iteration bound; these include the longest path matrix (LPM) and the minimum cycle mean (MCM) methods. The iteration bound of multirate DFGs is also addressed.