Simultaneous Functional and Timing ECO

Abstract

Metal-only ECO is prevalent at design houses to perform incremental design changes to resolve last found functional and/or timing failures. However, it is hard to perform mixed functional and timing changes manually. Prior endeavors focus on functional or timing ECO alone, but we observe that separating them may fail to fix all timing violations. Consequently, this paper presents the first work to perform simultaneous functional and timing ECO. We use an augmented bipartite graph to model both types of ECO. In addition, through comprehensive constant insertion and bridging, the functional capability of each spare cell is enhanced, thus facilitating spare cell selection. Experimental results show that our simultaneous functional and timing ECO engine can successfully resolve mixed functional and timing ECO that is unsolvable by the sequential scheme. Moreover, our engine outperforms the state-of-the-art works for timing ECO with a 117X speedup, and for functional ECO with 6-15% wirelength reductions.