#### pbsoftmml

Joined Aug 29, 2018
2

The circuit as shown above.

Conditions known:

1. The op-amp is nonideal.
2. Both inputs have current flow, lets say 0.7 uA.
3. Only R_F is known, which is 450 KOhm.
4. Open-loop gain is high.
5. Close-loop gain needs to be around 13.
6. Initial V_in and V_out is unknown.

Question: How much voltage should be added to V_in to eliminate the impact from the non-ideal op-amp to the circuit? (So that V_in will be equal to V_in+V_x after the modification, and solve for V_x).

#### kubeek

Joined Sep 20, 2005
5,736
That looks like a homework type of problem. What steps did you do to try to solve it?

#### ArakelTheDragon

Joined Nov 18, 2016
1,350
That looks like a homework type of problem. What steps did you do to try to solve it?
Also do you understand the question?

#### kubeek

Joined Sep 20, 2005
5,736
Also do you understand the question?
I think the question asks to say what will be the error caused by input current of the opamp.

#### ArakelTheDragon

Joined Nov 18, 2016
1,350
I think the question asks to say what will be the error caused by input current of the opamp.
I did not mean you.

#### kubeek

Joined Sep 20, 2005
5,736
I did not mean you.
Then you probably should have quoted pbsoftmml and not me

#### ArakelTheDragon

Joined Nov 18, 2016
1,350
Then you probably should have quoted pbsoftmml and not me
I was just adding towards your question to him. I will know for next time.

#### WBahn

Joined Mar 31, 2012
26,398
I'd also be interested in knowing what the heck the title is supposed to mean? It seems pretty close to random-word babble, to me.

#### MrAl

Joined Jun 17, 2014
7,891

The circuit as shown above.

Conditions known:

1. The op-amp is nonideal.
2. Both inputs have current flow, lets say 0.7 uA.
3. Only R_F is known, which is 450 KOhm.
4. Open-loop gain is high.
5. Close-loop gain needs to be around 13.
6. Initial V_in and V_out is unknown.

Question: How much voltage should be added to V_in to eliminate the impact from the non-ideal op-amp to the circuit? (So that V_in will be equal to V_in+V_x after the modification, and solve for V_x).
Hi,

One thing that strikes me right off is that Vin appears to have zero source impedance so the input current only affects the other input node.

We really need to see your best attempt at doing this though.