Congestion driven incremental placement algorithm for standard cell layout

Abstract

Congestion minimization is the least understood in placement objectives, however, it models routability most accurately. In this paper, a new incremental placement algorithm C-ECOP for standard cell layout is presented to reduce routing congestion. Congestion estimation is based on a new routing model and a more accurate cost function. An integer linear programming (ILP) problem is formulated to determine cell flow direction and avoid the conflictions between adjacent congestion areas. Experimental results show that the algorithm can considerably reduce routing congestion and preserve the performance of the initial placement with high speed.