If the differential voltage gain and the common mode voltage gain of a differential amplifier are 48 dB and 2 dB respectively, then its common mode rejection ratio would be??

CMRR = Ad / Ac

           = 48/2 =24

Hi Aniruddha,

Please calrify my doubt

CMMR=Ad/Ac

But if the Ad and Ac are given in DB is the same formula can be used ? or will there be any change?

Thanks,

Deepti

Answer is 46db because 

 CMRR=Ad/Ac

When converted to DB

20 log CMRR=20log(Ad/Ac)

                         = 20logAd-20logAc

                          =48db-2db=46db

Wonderfully answered....thanks for giving detailed answers Deepti.....