- Thu Sep 12, 2013 2:22 pm
#163455
Hello,
In my last post I had calculated Vout of an op amp according to its common/differential mode gains which was:
Vout = A_cm * V_cm + A_d * V_d
Vout = -1.1*3.5V + 1.45*3V
Vout = -3.85V + 4.35V
Vout = 0.5V
I am reading up on the CMRR of an op amp. And I Quote:
CMRR = 20 Log (Ad/Acm)
CMRR = 10 Log (1.45/1.1)
CMRR = 2.399
Does this mean my op amp is horrible
8v
In my last post I had calculated Vout of an op amp according to its common/differential mode gains which was:
Vout = A_cm * V_cm + A_d * V_d
Vout = -1.1*3.5V + 1.45*3V
Vout = -3.85V + 4.35V
Vout = 0.5V
I am reading up on the CMRR of an op amp. And I Quote:
However, in real amplifiers there is always some variation and the ratio of the change to the output voltage with regards to the change in the common mode input voltage is called the Common Mode Rejection Ratio or CMRR. Opamps typically have a CMRR of around 80 dB and the higher the better.If we calculate the CMRR of my circuit I only get:
CMRR = 20 Log (Ad/Acm)
CMRR = 10 Log (1.45/1.1)
CMRR = 2.399
Does this mean my op amp is horrible
8v