Exploiting signal flow and logic dependency in standard cell placement

Abstract

Most existing placement algorithms consider only connectivity information during the placement process, and ignore other information available from the higher levels of design process. In this paper, we exploit the use of signal flow and logic dependency in standard cell placement by using the maximum fanout-free cone (MFFC) decomposition technique. We developed a containment tree based algorithm for splitting large MFFCs into smaller ones to get clusters with restricted sizes. We also developed a placement algorithm, named MFFC-TW, which first clusters the circuit based on MFFC decomposition and then feeds the clustered circuit to the Timberwolf 6.0 placement package. Very promising experimental results were obtained.