# Op-amp circuit analysis question

#### bobby19

Joined Jun 3, 2007
13
Hi,

I am having trouble with an op-amp question. I have attached it in the word document along with part of the solution. We are asked to calculate the equivalent inductance in terms of R's and C assuming the op-amps are ideal.

I can understand the analysis up until "Hence V2 = V3 - (i4/sC) = V5 - (1/sRC)V5"

For the life of my, I cannot see where the V5 - (1/sRC)V5 part is coming from. Any thoughts?

Thanks

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#### scubasteve_911

Joined Dec 27, 2007
1,203
Do you understand where V5 = (V1 - V2)/R is coming from?

The next step is a simple substitution, since [ V2 = V5 - (1/sRC)V5 ] and V1 = V3 = V5/R

I'm a bit confused about the /R term went though.. I didn't bother writing this out, I just looked at it and thought it seemed right.

Steve

#### bobby19

Joined Jun 3, 2007
13
Do you understand where V5 = (V1 - V2)/R is coming from?

The next step is a simple substitution, since [ V2 = V5 - (1/sRC)V5 ] and V1 = V3 = V5/R

I'm a bit confused about the /R term went though.. I didn't bother writing this out, I just looked at it and thought it seemed right.

Steve
Sorry what do you mean by V5 = (V1-V2)/R?? I understand that V1=V3=V5.

The part that is confusing me is V2 = V5 - (1/sRC)V5. Specifically I dont see where the -(1/sRC)V5 part is coming from.

Thanks