EE 332 Lesson 0816 - Coupling capacitors block DC and low...

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8/16/2010 1 ©UW EE TC Chen Microelectronic Circuit Design Jaeger/Blalock EE 331 DEVICES AND CIRCUITS I SOLID-STATE ELECTRONICS WEEK 9 ©UW EE TC Chen Microelectronic Circuit Design Jaeger/Blalock DIRECT-COUPLED AMPLIFIER / INTRODUCTION pnp CE amplifier npn CC amplifier (voltage follower) R I R S1 Q 3 v o v i R G R C2 R E2 R E3 R L R D1 V CC Q 2 Coupling capacitors block DC and low frequency signals, therefore we must use DC-coupled amplifiers when low frequency (or DC) amplifications is required. C 4 C 2 M 1 -V EE NMOS CS amplifier 4 ©UW EE TC Chen Microelectronic Circuit Design Jaeger/Blalock DIRECT-COUPLED AMPLIFIER / INTRODUCTION Question: Why do we alternate NMOS, pnp, and npn stages? Q 1 V c1 Q 2 Assuming: and for swing To operate in F.A.R., for swing Then reach 11 1 2 1 2 22 2 2 0.7 , 5.0 5.0 3 5.0 0.7 4.3 0.2 4.5 3 , 3.2 7.5 BE CE C E C BE CE C CE C CC V V V V V V V V V V V V V V V V V V V V V     V E2 V c2 5 ©UW EE TC Chen Microelectronic Circuit Design Jaeger/Blalock DIRECT-COUPLED AMPLIFIER / INTRODUCTION Question: Why do we alternate NMOS, pnp, and npn stages? Q 1 V c1 Q 2 V E2 V c2 If we cascade two or more similar stages, the DC voltage would soon approach V CC . Hence, no room for ac signal swing at outputs of last stage. Hence, by alternating we go up, down, up etc., and stay near V CC /2. 6 ©UW EE TC Chen Microelectronic Circuit Design Jaeger/Blalock DIRECT-COUPLED AMPLIFIER / EXAMPLE , , 2 2,3, 2,3 2,3 3 150 0.7 , 80 F BE ON AF VV Q V       Analyze the given multi-stage amplifier 1 12 23 24 10 , 1 , 620 , 1.6 , 1.4 , 4.7 , 3.3 , 250 , 22 , I G D SE CE L R k R M R R k R k R k R k R C C F R I R S1 Q 3 v o v i R G R C2 R E2 R E3 R L R D1 V CC =7.5V Q 2 C 4 C 2 M 1 -V EE= -7.5V 2 1 1 10 / 2.0 0.02 n TN K mA V M V V V   7 ©UW EE TC Chen
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This note was uploaded on 10/12/2010 for the course IT 23211 taught by Professor Tai during the Summer '10 term at Punjab Engineering College.

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EE 332 Lesson 0816 - Coupling capacitors block DC and low...

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