Electronics-I Lecture 31

Electronics-I Lecture 31 - Lecture 31 Electronics I 1 CE...

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Unformatted text preview: Lecture 31 Electronics I 1 CE Amplifier with R e • Adding R e leads to significant changes in amplifier characteristics • Amplifier T Model with r o • r o is large it can be eliminated with little effect on amplifier performance Lecture 31 Electronics I 2 CE Amplifier with R e • Input Resistance R in R in = R B || R ib R ib ≈ v i /i b i e = v i /(r e + R e ) i b = i e (1 - α )= i e /(1+ β ) i b = v i /[(r e + R e ) (1+ β )] R ib = v i /i b (replace i b ) = (r e + R e )(1 + β ) • Input resistance is (1 + β ) times the total resistance in the emitter • Multiplication by a factor of (1 + β ) is known as resistance-reflection rule Lecture 31 Electronics I 3 CE Amplifier with R e • Including R e substantially increases R i • R ib (with R e )/R ib (without R e ) • The designer can select R...
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This note was uploaded on 12/12/2010 for the course EE 1 taught by Professor Shahidanwar during the Spring '10 term at NUCES.

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Electronics-I Lecture 31 - Lecture 31 Electronics I 1 CE...

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