Question

For the circuit shown below express v0 as a function of v1 and v2.

(a) v0 = v1 + v2

(b) v0 = v2 –  v1

(c) v0 = v1 –  v2

(d) v0 =  -v1 – v2

I had been asked this question during a job interview.

This is a very interesting question from Difference Amplifiers in chapter Operational Amplifiers of Electronic Devices & Circuits

Answer 1

The correct answer is (b) v0 = v2 –  v1

The best I can explain: Considering the fact that the potential at the input terminals are identical and proceeding we obtain the given result.