13 - MOS Unity Gain Frequency / Bandwidth The unity gain...

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1 ECSE334 – Introduction to Microelectronics ECSE 334 Introduction to Microelectronics Roni Khazaka Lecture #13 ECSE334 – Introduction to Microelectronics 2 Khazaka - 2008 MOS Unity Gain Frequency / Bandwidth I o I i The unity gain frequency f T of a transistor is the frequency at which the intrinsic short circuit current gain of the transistor g m v gs r o v gs + - C gs C gd gs m gs gd gs m o v g v sC v g I = ) ( gd gs i gs C C s I v + = ) ( gd gs m i o C C s g I I + = ) ( 1 gd gs m i o C C g I I + = = ω ) ( gd gs m T C C g + = ) ( 2 gd gs m T C C g f + = π ECSE334 – Introduction to Microelectronics 3 Khazaka - 2008 BJT Unity Gain Frequency / Bandwidth I o I i The unity gain frequency f T of a transistor is the frequency at which the intrinsic short circuit current gain of the transistor g m v r o v + - C C μ v g v sC v g I m m o = r C C s I v i 1 ) ( + + = 1 ) ( 1 ) ( + + = + + = = r C C s r g r C C s g I I h m m i o fe r v sC 0 β r C C s I I h i o fe ) ( 1 0 + + = = ECSE334 – Introduction to Microelectronics 4 Khazaka - 2008 BJT Unity Gain Frequency / Bandwidth r C C s I I h i o fe ) ( 1 0 + + = = r C C ) ( 1 + = ) ( 0 C C g m T + = = ) ( 2 C C g f m T + = ECSE334 – Introduction to Microelectronics 5 Khazaka - 2008 BJT Unity Gain Frequency / Bandwidth ECSE334 – Introduction to Microelectronics 6 Khazaka - 2008 BJT Diff. Pair: Common Mode Gain v + Q 2 R C v C1 v E Q 1 R C v C2 V CC -V EE I v o -+ v - v icm v icm R EE
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2 ECSE334 – Introduction to Microelectronics 7 Khazaka - 2008 BJT diff pair: Common Mode Gain g m1 v π 1 v 1 + - v b1 g m2 v 2 v 2 + - v b2 R C R C icm v v O - + i c1 i c2 r 1 r 2 R EE icm v v c1 v c2 ECSE334 – Introduction to Microelectronics 8 Khazaka - 2008 Common Mode Gain: small signal model g m1 v 1 v 1 + - v b1 g m2 v 2 v 2 + - v b2 R C R C icm v v O - + i c1 i c2 r 1 r 2 2R EE icm v v c1 v c2 2R EE 0 ECSE334 – Introduction to Microelectronics 9 Khazaka - 2008 Common Mode Gain: CM half circuits g m1 v 1 v 1 + - v b1 g m2 v 2 v 2 + - v b2 R C R C icm v v O - + i c1 i c2 r 1 r 2 2R EE icm v v c1 v c2 2R EE 0 ECSE334 – Introduction to Microelectronics 10 Khazaka - 2008 Common Mode Half Circuit g m1 v 1 v 1 + - v b1 R C icm v i c1 r 1 2R EE v c1 icm EE v R r r v ) 1 ( 2 + + = β icm EE C m C m c v R r R r g R v g v ) 1 ( 2 1 + + = = ) 1 ( 2 1 + + = EE C icm c R r R v v EE C EE e C icm c R R R r R v v 2 2 1 α + = ECSE334 – Introduction to Microelectronics 11 Khazaka - 2008 Small Signal Common Mode Gain + - v o Common Mode input Î single ended output + - v o + - Common Mode input Î Diff output 0 = = icm o cm v v A 0 1 2 = = c c o v v v EE C icm d cm R R v v A 2 = = v icm v icm ECSE334 – Introduction to Microelectronics 12 Khazaka - 2008 Common Mode Rejection Ratio + - v o + - v icm Common Mode input Î Diff output = = cm d A A CMRR Assumes Perfectly matched transistors!
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This note was uploaded on 01/27/2011 for the course ECSE 334 taught by Professor Anashamoui during the Spring '10 term at McGill.

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13 - MOS Unity Gain Frequency / Bandwidth The unity gain...

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