GATE 2018 EC – Question 48
An op-amp based circuit is implemented as shown below.
In the above circuit, assume the op-amp to be ideal. The voltage (in volts, correct to one decimal place) at node A, connected to the negative input of the op-amp as indicated in the figure is ________.
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: 0.49 to 0.51
Explanation
The linear gain would be $-31$, giving $-31$ V, which exceeds the $-15$ V supply, so the output saturates at $-15$ V and there is no virtual short. Then node A is set by the divider between the $1$ V input and the output: $V_A=\frac{1\times31+(-15)\times1}{32}=0.5$ V.