Question

Designing a high-gain op-amp circuit with tight output voltage tolerance. Which of the following factors becomes critically important in component selection?

• A. Slew rate of the op-amp
• B. Input offset voltage of the op-amp
• C. Power supply rejection ratio (PSRR) of the op-amp
• D. Common-mode rejection ratio (CMRR) of the op-amp

Hint:

High gain? Even microvolt offsets get amplified! Always check the input offset voltage.

Answer 1

The Correct Option is B

When designing a high-gain operational amplifier (op-amp) circuit where precision is critical and the output voltage must remain tightly controlled, the most important parameter is the input offset voltage. This is the small differential voltage required between the input terminals to make the output zero when ideally it should be.
In high-gain configurations: \[ V_{\text{out}} = A_v (V_{+} - V_{-}) \] Even a tiny input offset (\(\mu V\) range) gets multiplied by the large gain (\(A_v\)), leading to significant error in output. 

Why the other options are less relevant here:

• (A) Slew rate affects fast signal transitions, not DC accuracy.
• (C) PSRR matters with power supply noise, but isn’t dominant in DC precision.
• (D) CMRR is important in differential input rejection, but input offset dominates for high-gain DC applications.

Therefore, the input offset voltage is the most crucial factor when designing high-gain, tight-tolerance circuits.