Pulsed-Latch Aware Placement for Timing-Integrity Optimization

Abstract

Utilizing pulsed-latches in circuit designs is one emerging solution to timing improvements. Pulsed-latches, driven by a brief clock signal generated from pulse generators, possess superior design parameters over flip-flops. If the pulse generator and pulsed-latches are not placed properly, however, pulse-width degradations at pulsed-latches and thus timing violations might occur. In this paper, we present a unified placement framework for pulsed-latches to maintain the timing integrity. Our new placer has the following distinguished features: 1) a multilevel analytical placement framework to effectively prevent the potential pulse-width distortion problem; 2) a physical-location aware pulse-generator insertion algorithm to identify each desired group of a pulse generator and latches; and 3) a new optimization gradient for global placement to consider the impact of load capacitance of generators. Experimental results show that our placement flow can effectively consider pulse-width integrity and thus achieve much smaller total/worst negative slacks with marginal wirelength overheads, compared to a leading commercial and an academic placement flows.