- Wed Sep 18, 2013 9:25 am
#163659
Hi guys,
I am reading up a an article concerning CMRR at:
http://en.wikipedia.org/wiki/Common-mod ... tion_ratio
There is two formulas, the first:
CMRR = 20Log(Ad/Acm)
and the 2nd:
Vout = (V+ - V-) x Gopenloop +/- Vcm/10^CMMR/20
When do we use the first one and when do we use the 2nd one?
The reason I ask is because the 2nd one seems to be used when we are testing an op amp alone (without any resistors connected)???
All feedback is appreciated!
I am reading up a an article concerning CMRR at:
http://en.wikipedia.org/wiki/Common-mod ... tion_ratio
There is two formulas, the first:
CMRR = 20Log(Ad/Acm)
and the 2nd:
Vout = (V+ - V-) x Gopenloop +/- Vcm/10^CMMR/20
When do we use the first one and when do we use the 2nd one?
The reason I ask is because the 2nd one seems to be used when we are testing an op amp alone (without any resistors connected)???
All feedback is appreciated!