An Op-amp has a common mode gain of 0.01 and a differential gain of 105. Its CMRR would be

The Common Mode Rejection Ratio (CMRR) of an operational amplifier (Op-amp) is the ratio of the differential gain to the common mode gain. It is usually expressed in decibels (dB).

Given:

• Differential gain (Ad) = 105
• Common mode gain (Ac) = 0.01

The formula to calculate CMRR is:

CMRR = 20 log (Ad / Ac)

Substituting the given values:

CMRR = 20 log (105 / 0.01)

First, calculate the ratio of Ad to Ac:

105 / 0.01 = 10500

Then, take the logarithm (base 10) of this ratio:

log(10500) ≈ 4.02

Finally, multiply this result by 20 to get the CMRR in dB:

CMRR = 20 * 4.02 = 80.4 dB

So, the CMRR of the Op-amp is approximately 80.4 dB.