Crosslink insertion for variation-driven clock network construction

Abstract

Link based non-tree clock network is an effective and economic way to reduce clock skew caused by variations. However, it is still an open topic where links should be inserted in order to achieve largest skew reduction with smaller extra resources. We propose a new method using linear program to solve this problem in this paper. In our approach, clock skew in a non-tree clock network is computed using the delay model in [13] and the information is used to select the node pairs for link insertion. Tradeoff between crosslink length and skew reduction effect is explored. Based on the analysis, we propose a new algorithm to insert crosslinks into a clock network. We compare our work with the method in [1] and a recent work [4] which inserts links between internal nodes of a tree. Experiments show that our method can reduce skew under variations effectively.