Lecture 29 and 30_v2 - Lectures 29 and 30 More op-amp...

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Spring 2011 ECE 2100, Cornell University, Prof. Molnar 1 Lectures 29 and 30 More op-amp circuits
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Spring 2011 ECE 2100, Cornell University, Prof. Molnar 2 Most common amplifiers Inverting: Overall gain = -R F /R 1 Input resistance =R 1 V 1 =0 Noninverting: Overall gain = (R 1+ R F )/R 1 Input resistance = V 1 =Vin R F R 1 V 1 V in V out - + R F R 1 V 1 V in V out + -
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Spring 2011 ECE 2100, Cornell University, Prof. Molnar 3 Finite gain: examples Inverting: R1=1k ,RF=10k A=1000 Æ G~-9.9 A=100 Æ G~-9 A=10 Æ G~-4.75 () A R R AR Vin Vout G F F + + = = 1 1 Noninverting: If set RF Æ 0 Or R1 Æ Gain Æ A/(A+1) ~1 R F R 1 V 1 V in V out - + V 1 V in V out + - ( ) () A R R R R A Vin Vout G F F + + + = = 1 1 1
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Spring 2011 ECE 2100, Cornell University, Prof. Molnar 4 Some causal intuition Op-amp doesn’t respond instantly, but has infinite gain if: dV out /dt=k(V + -V - ) If (V + -V - )>0, V out Æ eventually For the circuit shown, So, if Vin steps from 0V Æ 1V Vout slopes downward But this decreases V1 Vout slope decreases Vout settles to constant as: 1 1 1 R R R V R V V F out F in + + = R F R 1 V 1 V in V out - + 1 1 1 1 1 0 R R V V R R R V R R R V V F in out F F in F out = + + 1 1 R R R V V F F in + Vin V1 Vout
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Spring 2011 ECE 2100, Cornell University, Prof. Molnar
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This note was uploaded on 06/10/2011 for the course ECE 2100 taught by Professor Kelley/seyler during the Spring '05 term at Cornell University (Engineering School).

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Lecture 29 and 30_v2 - Lectures 29 and 30 More op-amp...

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