Planar-CRX: A Single-Layer Zero Skew Clock Routing in X-architecture

Shen Weixiang1,  Cai Yici1,  Hong Xianlong1,  Hu Jiang2,  Lu Bing3
1Tsinghua University, 2Texas A&M University, 3Cadence Design


With its advantages in wirelength reduction and routing flexibility compared with conventional Manhattan routing, X-architecture has been proposed and applied to modern IC design. As a critical part in high-performance integrated circuits, clock network design meets great challenges due to feature size decrease and clock frequency increase. In order to eliminate the delay and attenuation of clock signal introduced by the vias, and to make it more tolerant to process variations, in this paper, we propose an algorithm of a single-layer zero skew clock routing in X-architecture(called Planar-CRX). Our Planar-CRX method integrates the extended Deferred-Merge Embedding algorithm (DME-X, which extends DME to X-architecture) with modified Ohtsuki's line-search algorithm to minimize the total wirelength and the bends. Compared with planar clock routing in the Manhattan plane, our method achieves a reduction of 6.81% in total wirelength on average, and fewer bends. Experimental results also indicate that our solution is comparable with previous non-planar zero skew clock routing algorithm.