Question

For an Op-amp, CMRR = $10^5$ and differential gain = $10^6$, what is the common mode gain of the Op-amp?

• A. $10^6$
• B. $2 \times 10^6$
• C. $1$
• D. $10$

Hint:

CMRR = Differential gain Common-mode gain.

Answer 1

The Correct Option is D

Concept: Common Mode Rejection Ratio (CMRR) is defined as: \[ \text{CMRR} = \frac{A_d}{A_c} \] where:
• $A_d$ = Differential gain
• $A_c$ = Common mode gain

Step 1: Rearranging formula \[ A_c = \frac{A_d}{\text{CMRR}} \]

Step 2: Substitute values \[ A_c = \frac{10^6}{10^5} = 10 \] \[ \therefore \text{Correct answer is (D)} \]