Lecture31-The u741 Op Amp

# Lecture31-The u741 Op Amp - Lecture 31 What makes up an...

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ECE 3040 - Dr. Alan Doolittle Georgia Tech Lecture 31 What makes up an Op-Amp: 741 example Reading: Jaeger 16.8 and Notes

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ECE 3040 - Dr. Alan Doolittle Georgia Tech What Makes up an Op Amp? The “741” Example Current Mirror Used as an Active Load 2 1 2 4 1 3 2 C C EE C C C C V V I I I I I = = = = = DC Analysis If we can insure that the mirrored currents are equal, I C3 I C1 I C4 I C2 V C2 V C1
ECE 3040 - Dr. Alan Doolittle Georgia Tech What Makes up an Op Amp? The “741” Example Current Mirror Used as an Active Load () L id m L o o id m out id m id m id m C C O id m C C C C C R v g R r r v g v v g v g v g i i i v g i i i i i = = + = + = = = = = 4 2 2 4 2 1 4 1 3 2 2 2 AC Analysis i C3 i C1 i C4 i C2 v C2 =v out v C1 i O L O A D 0.5v id 0.5v id - + - + By using an active load (transistors), we obtain the “Full” gain of a CE stage even though we have a single-ended output. (Remember that for a passive load, resistor, the single ended gain was half the CE gain).

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ECE 3040 - Dr. Alan Doolittle Georgia Tech What Makes up an Op Amp? The “741” Example Output Stages: “Class A” Output Stage v out So far, the Common Collector output stages (again chosen for very low output impedance) has consisted of a single transistor. This transistor must carry the output current (delivered to R1) and the bias current (I DC ). This results in wasted power in the output stage and possible overheating. v
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## This note was uploaded on 08/23/2011 for the course ECE 3040 taught by Professor Doolittle during the Spring '11 term at University of Florida.

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Lecture31-The u741 Op Amp - Lecture 31 What makes up an...

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