ABSTRACT
This chapter explains the D.C. characteristics of bipolar junction transistors (BJTs) and field-effect transistors (FETs). It describes the a.c. characteristics and equivalent circuits of bipolars and FETs. The chapter introduces the operation of some basic analogue and digital circuits using both types of transistor. Transistors are the ‘active’ devices of electronics. They are capable of controlling power from a D.C. power supply, in response to a low-power input signal, and providing a much greater output power. So they can provide power gain. This is the basic function of an amplifier. Silicon bipolar transistors are three-terminal devices consisting of two pn junctions formed back to back in a single crystal of silicon. FETs, like bipolars, are used for a wide variety of analogue and digital circuits. FET analogue circuits have close similarity with bipolar ones, differing mainly in their gate bias arrangements.
