cellTK: Automated Layout for Asynchronous Circuits with Nonstandard Cells

Robert Karmazin, Carlos Tadeo Ortega Otero, and Rajit Manohar

Asynchronous circuits are an attractive option to overcome many challenges currently faced by chip designers, such as increased process variation. However, the lack of CAD tools to generate asynchronous circuits limits the adoption of this promising technology. In this absence of CAD tools, the most time consuming part of chip design is the back-end (physical design) effort. We propose a complete design infrastructure to physically implement an asynchronous digital netlist with orders of magnitude time savings over expert human effort. The core of this flow is the ability to generate customized logic that is compatible with available ASIC flows. We evaluate our flow against several asynchronous circuit benchmarks for which full custom physical implementations exist. Compared to handoptimized custom designs, our flow produces layout that has, on average, a 51% area overhead, with a 12% increase in energy and a 9% increase in delay.