EE 330 Lect 30 Spring 2011

EE 330 Lect 30 Spring 2011 - EE 330 Lecture 30 Basic...

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EE 330 Lecture 30 Basic amplifier architectures
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How does g m vary with I DQ ? DQ OX m I L W C g   T GSQ m V V L W μC g EBQ T GSQ m V 2I V V g Varies with the square root of I DQ Varies linearly with I DQ Doesn’t vary with I DQ Review from Last Time
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Examples B E C V CC V in R 1 V out V EE Q 1 B E C V CC =12V V in R 1 =2K V out Q 1 R B =500K C 1 =1uF Compare the small-signal equivalent circuits of these two structures R 1 V IN V OUT R 1 V IN V OUT R B Since Thevenin equivalent circuit in red circle is V IN , both circuits have same voltage gain Review from Last Time
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Examples R 1 =2K Q 1 V OUT V CC =12V V IN (t) R B =500K C=1uF Several different biasing circuits can be used Biasing Circuit Review from Last Time
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Examples Determine V OUTQ , A V , R IN B E C V CC =12V V in R 1 =2K V out Q 1 R B =500K C 1 =1uF Review from Last Time
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Examples Determine V OUT and V OUT (t) if V IN =.002sin(400t) B E C V CC =12V V in R 1 =2K V out Q 1 R B =500K C 1 =1uF Review from Last Time
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Examples R 1 =2K Q 1 V OUT V CC =12V V IN (t) R B =500K C=1uF Determine the SS voltage gain β=100 R 1 V IN V OUT R B ss equivalent circuit Have seen this circuit before but will repeat for review purposes R 1 V OUT V IN R B g m V BE V BE i B g π ss equivalent circuit m BE 1 gR OUT  V V BE IN V V 1 m A R g CQ 1 V t IR A- V This basic amplifier structure is widely used and repeated analysis serves no useful purpose 177 V 2.3mA 2K 26mV Review from Last Time
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Examples R 1 =2K Q 1 V OUT V CC =12V V IN (t) R B =500K C=1uF Determine the R IN β=100 R 1 V IN V OUT R B ss equivalent circuit IN in IN R V i R 1 V OUT V IN R B g m V BE V BE i B g π R IN i IN // in R B Rr Usually R B >>r π // in R B R r r  CQ in t I R βV r Review from Last Time
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Examples Determine V OUT and V OUT (t) if V IN =.002sin(400t) B E C V CC =12V V in R 1 =2K V out Q 1 R B =500K C 1 =1uF OUT OUTQ V IN V V +A V 7.4 .002 sin(400 ) OUT V -177 Vt  7.4 .35 sin(400 ) OUT V - Review from Last Time
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Amplifier input impedance, output impedance and gain are usually of interest Why? y 11 y 11 V 2 y 21 V 1 y 12 V 2 V 1 Amplifiers can be modeled as a two-port R IN V 2 A V V 1 V 1 R OUT Amplifier usually unilateral and thevenin equivalent output port often more standard
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R IN V OUT A V V 1 V 1 R OUT V IN Determination of Amplifier Parameter A V
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R IN V OUT A V V 1 V 1 R OUT V IN I 1 Determination of Amplifier Parameter R IN
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R IN V X A V V 1 V 1 R OUT I X Determination of Amplifier Parameter R OUT
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This document was uploaded on 01/31/2012.

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EE 330 Lect 30 Spring 2011 - EE 330 Lecture 30 Basic...

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