TABLE OF CONTENTS This appendix reviews very briefly some basic transistor theory. The authors assume that anyone reading it will have a basic working knowledge of circuit theory from an undergraduate electrical engineering program or the equivalent. A short appendix cannot hope to replace the many detailed texts available on this subject, but it is included here as a reference for a few very common equations and basic results.
Traditionally, bipolar transistors are preferred for high-speed circuits due to the higher values of transconductance achievable for a given amount of bias current. However, it is often necessary to use a process that can also be used to implement back-end digital or DSP functions. In such cases, a BiCMOS or straight CMOS process is preferred. If a BiCMOS process is used, bipolar transistors can be used for RF, possibly adding PMOS transistors for power-control functions. However, for economic reasons, or due to the need to use a particular CMOS-only process to satisfy the back-end requirements, it may be necessary to implement all circuits in pure CMOS. Figure B.1 shows basic PMOS and NMOS transistors. An NMOS transistor is made by growing an oxide layer on top of a p type substrate [1]. The oxide layer is patterned from the gate (G) of the transistor. n+ regions are then implanted on either side of the gate to form the source (S) and drain (D) of the transistor. The gate also has a conductive layer (typically polysilicon) placed...
