What is the CMRR in decibels (dB) for a typical 741C op-amp? Given the typical open-loop differential gain for the 741C is 200,000 and the typical commonmode gain is 6.3.

Answer 1

The Common Mode Rejection Ratio (CMRR) is defined as the ratio of the differential gain to the common-mode gain.

CMRR = Differential gain / Common-mode gain

CMRR = 200,000 / 6.3
CMRR = 31,746

To express this value in decibels (dB), we can use the formula:

CMRR(dB) = 20log10(CMRR)

CMRR(dB) = 20log10(31,746)
CMRR(dB) = 90.2 dB

Therefore, the CMRR of a typical 741C op-amp is approximately 90.2 dB.