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Unformatted text preview: Bob York Transistor Basics - BJTs Bob York Back to TOC V CE Bipolar Junction Transistors (BJTs) Key points: BJTs are current-controlled devices Every BJT has a base , collector , and emitter The base current controls the collector current Thereare two types of BJTS: NPN and PNP The use of BJTs is conceptually similar to the use of FETs with some differences in biasing and details of operation. The NPN is analogous to the N-channel FET The PNP is analogous to the P-channel FET In the forward active region the collector current varies linearly with the base current. This linear dependence simplifies bias calculations and also makes BJTs attractive for many analog circuit applications NPN Common-emitter (CE) configuration I c, , mA Forward active region Increasing I b 50 A 40 A 30 A 20 A 10 A 0 A 1 2 3 4 5 , 0.2-0.3V ce sat V Base Emitter Collector NPN BJT Base Emitter Collector PNP BJT I c I b V ce B C E Ideal NPN CE Characteristics c b I I Forward active region: beta is the current gain Bob York...
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This note was uploaded on 03/17/2010 for the course ECE 2B taught by Professor York during the Winter '07 term at UCSB.
- Winter '07