ADA4927 Common Mode Gain

Document created by analog-archivist Employee on Feb 23, 2016
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Why is there a difference between the input Vocm and the Vout,cm at the output
pins, OUT+ and OUT-?


Be aware that ∆Vout,cm/∆Vocm Gain is not typically unity, and can range from
0.90 (minimum) – 1.00 (maximum), see table 2 (page 4) of the ADA4927 datasheet
(Rev A 8/09). For example, a Vocm of 630.5mV causes a Vout,cm = 609.1mV output
on OUT+. Initially, it seems to differ a lot but, when you calculate  ∆Vout,cm/
∆Vocm = 0.966, we see that this is very close to the typical value of 0.97
stated in the datasheet.