Matching-based methods for high-performance clock routing

Abstract

The authors point out that minimizing clock skew is important in the design of high-performance VLSI systems. A general clock routing scheme that achieves extremely small clock skews while still using a reasonable amount of wirelength is presented. The routing solution is based on the construction of a binary tree using geometric matching. For cell-based designs, the total wirelength of the clock routing tree is on average within a constant factor of the wirelength in an optimal Steiner tree, and in the worst case is bounded by O( square root l/sub 1/l/sub 2/*1 square root n) for n terminals arbitrarily distributed in the l/sub 1/*l/sub 2/ grid. The bottom-up construction readily extends to general cell layouts, where it also achieves essentially zero clock skew within reasonably bounded total wirelength. The algorithms have been tested on numerous random examples and also on layouts of industrial benchmark circuits. The results are very promising: the clock routing yields near-zero average clock skew while using total wirelength competitive with that used by previously known methods.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>