Asynchronous Circuit Principles and a Survey of Associated Design Tools

Planning and implementing a semiconductor integrated circuit is a highly complex process. Although physical limits seem to be approaching, it currently follows a growing evolutionary path. As deep submicron technologies evolve towards perhaps even sub-nano geometries, the design process complicates accordingly. Once subtle in higher geometry nodes, some effects become relevant or even dominant. Examples are effects that tamper the reliability of wires, such as crosstalk, or the adequate behaviour of gates, such as the increasing sensitivity to single event effects. Design techniques must thus also evolve, to provide a wide range of tools to deal with new effects during the integrated circuit design and test processes. This tutorial covers one set of design techniques that is often overlooked, but which can reveal themselves instrumental in dealing with the mentioned technology evolution, the use of clockless or asynchronous circuits. The tutorial is divided into three parts: first it introduces a metamodel for the digital circuit design process enabling to reason about distinct design styles; second, it covers the main principles of asynchronous circuit design, differentiating it from mainstream circuit design techniques such as conventional synchronous design; the third and last part presents a set of tools and systems that can be employed to effectively design asynchronous design, with emphasis on material that can be used to produce manufacturable circuits and systems, often associated to commercial integrated circuit synthesis, implementation and test tools and frameworks.