Question

A differential amplifier has defferental gain of 20000.and cmrr=80 db the common mode gain is given by ..........​

Answer 1

Common mode gain, $\bf {A_{CM}}$ is 2

Explanation:

Given,

differential gain = 2000

CMRR = 80 db.

The formula to calculate CMRR =  $20log_{10}(\frac{A_d}{A_{CM}})$...........(1)

where, $A_d =$ differential gain

$A_{CM} =$ common mode gain

Put the values in eq. (1)

$80 = 20log_{10}(\frac{20,000}{A_{CM}})$

$A_{CM}= \frac{20000}{10^4} =2$

Thus, common mode gain, $A_{CM}$ is 2