Timing Driven Placement for Quasi Delay-Insensitive Circuits

Robert Karmazin, Stephen Longfield, Carlos Tadeo Ortega Otero, and Rajit Manohar

Asynchronous circuits offer promise in handling current and future technology scaling challenges. Unfortunately, their impact has been limited by the lack of CAD support. We present A-NTUPLACE, a timing-driven placer uniquely suited to handling quasi delay-insensitive circuits. Our tool uses a generalization of repetitive event rule systems to identify critical signal transitions. The cell placement engine, based on the leading academic placer NTUPlace3, incorporates net weights to minimize critical wirelengths as well as a novel balancing scheme to ensure isochronic fork constraints are met. We show that our placer is effective at both prioritizing selected nets as well balancing forks, demonstrating improvements in 3 of our 4 benchmarks.