Asynchronous Circuit Design

Preface

An important scientific innovation rarely makes its way by gradually winning over and converting its opponents: it rarely happens that Saul becomes Paul. What does happen is that its opponents gradually die out and that the growing generation is familiarized with the idea from the beginning.

—Max Planck

I must govern the clock, not be governed by it.

—Golda Meir

All pain disappears, it's the nature of my circuitry.

—nine inch nails

In 1969, Stephen Unger published his classic textbook on asynchronous circuit design. This book presented a comprehensive look at the asynchronous design methods of the time. In the 30 years hence, there have been numerous technical publications and even a few books [37, 57, 120, 203, 224, 267, 363, 393], but there has not been another textbook. This book attempts to fill this void by providing an updated look at asynchronous circuit design in a form accessible to a student who simply has some background in digital logic design.

An asynchronous circuit is one in which synchronization is performed without a global clock. Asynchronous circuits have several advantages over their synchronous counterparts, including:

1. Elimination of clock skew problems. As systems become larger, increasing amounts of design effort is necessary to guarantee minimal skew in the arrival time of the clock signal at different parts of the chip. In an asynchronous circuit, skew in synchronization signals can be tolerated.
2. Average-case performance. In synchronous systems, ...