Hello all,

I've been working on the following question (See figure attached).

I'm on part (ii) and the solution gives this circuit (See other figure attached) as the one that will provide a gain of +2V/V.

I'm tried doing some analysis on the circuit to figure out whether this is right or not but I can't conclude that it indeed gives a gain of 2V/V.

What am I doing wrong?

I've got a feeling my calculation for \(V_{+}\) is wrong.

Can someone clarify?

 

In your diagram, V+ = Vin
So the gain is equal Av = 1+ R/R = 2V/V

 

The point to note is that the two resistors connected to the non-inverting input are in parallel. They do not form a potential divider in this example.

Perhaps you thought one of these resistors was connected to ground, having seen similar arrangements where this was the case? Circuits need to be read carefully.