EE 330 Lect 21 Spring 2011

EE 330 Lect 21 Spring 2011 - EE 330 Lecture 21 Bipolar...

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EE 330 Lecture 21 Bipolar Processes
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Simple dc model t BE V V B e I S I ~ t V V C e I S I ~ q kT V t t V V E S B e β A J I t V V E S C e A J I q kT V t J S is termed the saturation current density Process Parameters : J S , β Design Parameters: A E Environmental parameters and physical constants: k,T,q At room temperature, V t is around 26mV J S very small around .25fA/u 2 Review from Last Lecture
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Simple dc model V BE or I B Typical Output Characteristics 0 50 100 150 200 250 300 0 1 2 3 4 5 Vds Id I C V CE Forward Active Saturation Cutoff Forward Active region of BJT is analogous to Saturation region of MOSFET Saturation region of BJT is analogous to Triode region of MOSFET Review from Last Lecture
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Simple dc model Simplified Multi-Region Model I C V CE V BE1 V BE2 V BE3 V BE4 V BE5 I C V CE V BE1 V BE2 V BE3 V BE4 V BE5 V CESAT Ebers-Moll Model Simplified Multi-Region Model 1 CE BE tt -V V VV CE R C S E R AF V 1+β I J A e e 1+ βV      AF CE V V E S C V V 1 e A J I t BE V BE =0.7V V CE =0.2V I C =I B =0 CE BE -V V B S E FR 11 I J A e - e ββ t V V E S B e β A J I Forward Active Saturation Cutoff Review from Last Lecture
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Simple dc model Simplified Multi-Region Model AF CE V V E S C V V 1 e A J I t BE t V V E S B e β A J I q kT V t V BE =0.7V V CE =0.2V I C =I B =0 Forward Active Saturation Cutoff V BE >0.4V V BC <0 I C < β I B V BE <0 V BC <0 A small portion of the operating region is missed with this model but seldom operate in the missing region Review from Last Lecture
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Simple dc model Equivalent Simplified Multi-Region Model AF CE B C V V 1 βI I t BE V V E S B e β A J I q kT V t V BE =0.7V V CE =0.2V I C =I B =0 Forward Active Saturation Cutoff V BE >0.4V V BC <0 I C < β I B V BE <0 V BC <0 A small portion of the operating region is missed with this model but seldom operate in the missing region Review from Last Lecture
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Simplified dc model Forward Active βI B I B B C E βI B I B B C E 0.6V Mathematically V BE =0.6V I C =βI B V BE =0.6V I C =βI B (1+V CE /V AF ) Or, if want to show slope in I C -V CE characteristics AF DS CQ V R= I
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EE 330 Lect 21 Spring 2011 - EE 330 Lecture 21 Bipolar...

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