Lecture22

Eric pop ie i c b i e i c b i e b rrent amplification

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Unformatted text preview: atio: Illinois ECE440 Prof. Eric Pop IE I C B I E I C B I E B rrent amplification (common emitter gain): Cu C r ratio: IC ferCurrent ratio: 7 ation (common emitter gain): IE cation (common emitter gain): IC ification (common emitter gain): IC Current amplification Base current I IC I BIC 1 I B B (remember the base is n-type): 1 (common emitter gain): IB 1 I B Eric Prof. 1 Pop Illinois ECE440 Prof. Eric Pop Prof. Eric Pop Some electrons ___________ with injected holes. 7 Prof. Some electronsEric Pop into p+ (forward Spring 20137 injected 7 EE 332 biased EB). 7 Few electrons swept from thermal generation in reverse Emitter Injection Efficiency IE E ICp IEp IEn ICn IC C IB IEp IEp γ= = IE IEp + IEn Can we make the emitter see holes alone? 0 ≤ γ ≤1 EE 332 Spring 2013 Base Transport Factor IE E ICp IEp IEn ICn IC C IB ICp αT = IEp 0 ≤ αT ≤ 1 Can all injected holes make it to the collector? EE 332 Spring 2013 Collector Collector Current Current EE 332 Spring 2013 PNP BJT Electrostatics Under normal operating conditions, the BJT may be viewed electrostatically as two independent pn junctions EE 332 Spring 2013 Carrier Activity under Active Mode Biasing VEB > 0 VCB > 0 Few recombine in the base Collector Fields drive holes far away where they can’t return thermionically Large injection of Holes Most holes diffuse to collector EE 332 Spring 2013 BJT Normal Mode and Gain. Forwar...
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This document was uploaded on 02/18/2014.

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