Question

Assertion (A): The ability of a differential amplifier to reject a differential mode signal is called its figure of merit. Reason (R): The ideal value of figure of merit of a differential amplifier is infinite.

• A. Both (A) and (R) are correct and (R) is correct explanation
• B. Both (A) and (R) are correct but (R) is not explanation
• C. (A) is correct but (R) is incorrect
• D. (A) is incorrect but (R) is correct

Hint:

Differential amp: amplifies differential, rejects common-mode.

Answer 1

The Correct Option is D

Concept: The figure of merit of a differential amplifier is CMRR (Common Mode Rejection Ratio), which measures the ability to reject common-mode signals, not differential signals.

Step 1: Analyze Assertion Assertion states rejection of differential signal → this is incorrect. A differential amplifier is designed to amplify differential signals, not reject them. \[ \Rightarrow \text{Assertion is FALSE} \]

Step 2: Analyze Reason Ideal CMRR: \[ \text{CMRR} = \frac{A_d}{A_c} \rightarrow \infty \] This means perfect rejection of common-mode signal. \[ \Rightarrow \text{Reason is TRUE} \] \[ \therefore \text{Correct answer is (D)} \]