ECT 2440 Chapter Notes - Chapter 13: Voltage Source, Power Gain, List Of Major League Baseball Career Total Bases Leaders
Document Summary
Bipolar junction transistors (bjts) are constructed as layers of semiconductor materials (usually silicon) doped with suitable impurities. In n-type material, conduction is due mainly to negatively charged electrons. In p-type material, conduction is due mainly to positively charged holes: an npn transistor consists of a layer of p-type material between two layers of n- type material. The layers are called: the emitter, base, and collector. Each pn junction forms a diode, but if the junctions are made very close together in a single crystal of the semiconductor, the current in one junction affects the current in another. In normal operation as an amplifier, the base-collector junction is reverse biased and the base-emitter junction is forward biased. The shockley equation gives the emitter current ( ) in terms of the base-to-emitter voltage ( Appropriate substitution can alternatively express the equation as: is slightly less than unity. Thus: the base current can be expressed as:
