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posted by  rocker4227 on 7/15/2008 12:00:44 PM  |  status: Live  

Ideal op-amp circuit

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posted by Shree_vani on 7/15/2008 12:52:08 PM  |  status: Live
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The first opamp circuit is an inverting amplifier, whose output is given by
The second opamp circuit is an voltage follower, whose output Vo2 is equal to the voltage at the non-inverrting input.
The voltage at the noninverting input is given by
Therefore
 
The third opamp circuit is an summing amplifier, with inputs Vo1 and Vo2, its output is given by
 
Note:
The 9R reisitance in the third circuit will be in parallel with the feedback resistance R, hence the equivalent feedback reisitance will be
Rf = R || 9R = 0.9R
Then
Vo = (0.9) (5+20Vi) = 4.5 + 18Vi
 
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