Question

What is done to compensate the voltage, when V1 > V2?

(a) Move the wiper towards +Vcc

(b) Move the wiper towards –Vee

(c) Keep the wiper at the center of potentiometer

(d) None of the mentioned

The question was posed to me during an online interview.

This interesting question is from Input Offset Voltage topic in division Operational Amplifier Fundamentals of Linear Integrated Circuits

Answer 1

The correct answer is:

(b) Move the wiper towards –Vee

Explanation: In an operational amplifier circuit, especially when dealing with offset voltage compensation, the input offset voltage can be corrected using a potentiometer. The potentiometer is typically used to balance or nullify the difference in input voltages.

When V1>V2V_1 > V_2V1​>V2​ (i.e., the non-inverting input is more positive than the inverting input), moving the wiper towards the negative supply voltage (–Vee) helps to reduce the offset voltage by adjusting the bias at the input. This action compensates for the input offset, making the output closer to the desired value.