Closed Loop Gain Formula Derivation - Why Superposition Theorem is valid for the inverting amp with finite loop gain op-amp.

[BlackMelon]

Hi,

I am reading about the closed loop gain formula for the inverting amp. The nonideality of the op-amp is only finite loop gain:
1. V+ ≠ V-
2. Vo = A*vid , where vid =V+ - V- and A is the op amp's open loop gain
On the 5th page, the author find the formula for V- of the inverting amp by using the superposition theorem. How can he apply it since Vo is not an independent voltage source?

Best Regards,
BlackMelon

 

[Delta Prime]

How can he apply it since Vo is not an independent voltage source?

Simple my Padawan he must learn to differentiate between non-linear and linear circuits. Wikipedia is your friend I would just be regurgitating information from scholars…
Like myself…

 

[poormystic]

Hi
Perhaps it's not the best textbook. Of course everybody has already told you to get The Art Of Electronics so do it.
I hope that your goal is to be able to use op-amps successfully in analog circuit designs.
It doesn't really look like the most helpful presentation to me but explaining why is a big job...
I'm past wanting to get into the details of all the algebra again but I remember that at the time I was studying I was very much helped by a cheap oscilloscope and a few op-amps and resistors. Also I took my maths very seriously.
Thumbs up and good luck.