L6-2 5.9.3 P5.167 CE with Emitter Resistor RE L5_2

# L6-2 5.9.3 P5.167 CE with Emitter Resistor RE L5_2 - E + r...

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Problem 5.167 CE With Emitter Resistor RE Lecture 6 Friday Jan.22, 2010 Zubair Rehman

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2 Figure 5.167 Replace R e  by R E
3 Solution Using Tee Model E e E e E c E e E E c E E e c s o E E e S C c C o e c C r R s s r R R s A sC r R sC R sC R r R V V s A sC R r V R I R V I I ) ( 1 * ) ( 1 ) ( * / 1 ) ( / 1 * + + + - = + + - = + + - = = + + - = - = r e = V T / I E Show I e = V s / [r e + R E + 1 / sC E ] reactance in emitter circuit A m = - R c / (R E + r e ) A m (R E = 0) = - R c / r e S = - 1 / [(R E + r e ) C E ] ω L = 1 / [(R E + r e ) C E ] f L = (ω L / 2 π ) = 1 / 2 π (R E + r e ) C E Midband Gain Reduction Factor e e E e E c e c r r R r R R r R + = + - - = ) /( /

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4 Solution Using Hybrid - P Model 1 / 1 * ) / 1 ( ( ) / 1 ( ( = 1 + + + 1 + - = - = - = + + 129( + = 129 + = + 129 + + = α β π sig E E e C C b C c o E E e sig b e E E b b sig V sC R r R R i R i V sC R r V i r r sC R i r i V A mid = - R C / R E + r e ϖ P = 1 / (r e + R E )C E ϖ L = 1 / (r e + R E )C E f L = 1 / (2 π (r e + R E )C E ) P mid E e e e E C sig o E E e e E C E E e C sig o s s A C R r s s r R R V V sC R r r R R sC R r R V V ϖ + = + + + - = + + + - = + + - = ) ( 1 * ) ( 1 1 1 * / 1
5 For R E = 0 A mid = - R C / r e f L = 1 / (2 π r e C E ) Midband Gain Reduction Factor = A m (R E = 0) / A m (R E > 0) = (R E + r e )/ r e f L Improvement Factor = f L (R E = 0) / f L (R E > 0) = (R E + r e ) / r e L are reduced by the factor (R
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Unformatted text preview: E + r e ) / r e a. I = 1 mA, R C = 10 k, C E = 100 μ F Find A m and f L with R E = 0. Then find the value of R E that lowers f L by a factor of 5. What will be the gain? r e = V T / I E = V T / I = 25 mV / 1 mA = 25 Ω R E = 0 ; A m = - R C / r e = - 10 k / 25 = -400 f L = 1 / [2 π x r e C E ] = 1 / 2 π x 25 x 100 μ = 63.7 Hz Value of R E that reduces f L by a factor of 5, (R E + r e ) / r e = 5 R E = 4r e = 4 x 25 = 100 Ω Midband Gain for R E = 100 Ω A mid (R E = 100 Ω ) = A mid (R E = 0) / 5 = - 400 / 5 = - 80...
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L6-2 5.9.3 P5.167 CE with Emitter Resistor RE L5_2 - E + r...

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