Introduction

The concept of data or information processing arises in a variety of fields. Understanding the principles behind this concept is fundamental to computer design, communications, manufacturing process control, biomedical engineering, and an increasingly large number of other areas in technology and science. It is impossible to imagine modern life without computers for generating, analyzing and retrieving large amounts of information, as well as communicating information regardless of location.

Technologies for designing and building microelectronics-based computational equipment have been steadily advancing ever since the first commercial discrete integrated circuits (ICs) were introduced in the late 1950's [3].¹ As predicted by Moore's Law in the 1960's [4], integrated circuit density has been doubling approximately every 18 months. This scaling of circuit size has been accompanied by a similar exponential increase in circuit speed (or more precisely, clock frequency). These trends of steadily increasing circuit size and clock frequency are illustrated in Figures 1.1 and 1.2, respectively. As a result of this amazing revolution in semiconductor technology, it is not unusual for modern integrated circuits to contain over ten million switching elements (i.e., transistors) packed into a chip area as large as 500 mm² (e.g., [5, 6, 7]). This truly exceptional technological capability is due to advances in both design methodologies and physical manufacturing technologies. Research and experience demonstrate that this trend of exponentially increasing integrated circuit computational power will continue into the foreseeable future.