TABLE OF CONTENTS The two most prevalent integrated-circuit technologies are bipolar and MOS. Within each of these families are various subgroups as illustrated in Fig. 2.0-1, which shows a family tree of some of the more widely used silicon integrated-circuit technologies. For many years the dominant silicon integrated-circuit technology was bipolar, as evidenced by the ubiquitous monolithic operational amplifier and the TTL (transistor-transistor logic) family. In the early 1970s MOS technology was demonstrated to be viable in the area of dynamic random-access memories (DRAMs), microprocessors, and the 4000-series logic family. By the end of the 1970s, driven by the need for density, it was clear that MOS technology would be the vehicle for growth in the digital VLSI area. At this same time, several organizations were attempting analog circuit designs using MOS [ [1] [2] [3] [4]]. NMOS (n-channel MOS) technology was the early technology of choice for the majority of both digital and analog MOS designs. The early 1980s saw the movement of the VLSI world toward silicon-gate CMOS, which has been the dominant technology for VLSI digital and mixed-signal designs ever since [ [5], [6]]. Recently, processes that combine both CMOS and bipolar (BiCMOS) have proved themselves to be both a technological and market success, where the primary market force has been improved speed for digital circuits (primarily in static random-access memories, SRAMs). BiCMOS has potential as well in analog design due to the enhanced performance that a bipolar transistor provides in the context of CMOS technology.
