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What is common mode rejection (CMR) of an operational amplifier?

Latest Updated:12/01/2011

Question:

What is common mode rejection (CMR) of an operational amplifier?

Answer:

CMR indicates the ratio of the input voltage to the varied input offset voltage when the input offset voltage has changed due to a change in the input voltage.

CMR=ΔVI/ΔVIO



Normally the DC variation is the target.
If the CMR value is large, it indicates that, when VI is the same, VIO is small.
Therefore, this expresses the extent to which, under identical conditions, mode signals that affect the circuit (noise, drift, etc.) are suppressed with respect to the two inputs.
Normally the DC variation is the target. If the CMR value is large, it indicates that, when VI is the same, VIO is small. Note that CMR may affect the circuit as an error at the output.
Suitable Products
Operational Amplifiers
UPD720201