PRINCIPLES OF ASYNCHRONOUS CIRCUIT DESIGN – A Systems Perspective

Asynchronous circuits have characteristics that differ significantly from thoseof synchronous circuits and, as will be clear from some of the later chaptersin this book, it is possible exploit these characteristics to design circuits withvery interesting performance parameters in terms of their power, performance,electromagnetic emissions (EMI), etc.Asynchronous design is not yet a well-established and widely-used design meth-odology. There are textbooks that provide comprehensive coverage of the underlying theories, but the field has not yet matured to a point where there is an estab-lished currriculum and university tradition for teaching courses on asynchronouscircuit design to electrical engineering and computer engineering students.As this author sees the situation there is a gap between understanding the fun-damentals and being able to design useful circuits of some complexity. The aimof Part I of this book is to provide a tutorial on asynchronous circuit design thatfills this gap.More specifically the aims are: (i) to introduce readers with background in syn-chronous digital circuit design to the fundamentals of asynchronous circuit de-sign such that they are able to read and understand the literature, and (ii) toprovide readers with an understanding of the “nature” of asynchronous circuitssuch that they are to design non-trivial circuits with interesting performance pa-rameters.The material is based on experience from the design of several asynchronouschips, and it has evolved over the last decade from tutorials given at a numberof European conferences and from a number of special topics courses taught at the Technical University of Denmark and elsewhere. In May 1999 I gave aone-week intensive course at Delft University of Technology and it was whenpreparing for this course I felt that the material was shaping up, and I set out to write the following text. Most of the material has recently been used anddebugged in a course at the Technical University of Denmark in the spring 2001.Supplemented by a few journal articles and a small design project, the text maybe used for a one semester course on asynchronous design.