Frank_Heart
Junior Member
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Posts: 29
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Hi, Repah,
If you want to do a CM step transient, then just short inputs and apply, 400mV <-> 500mV on the input.
If you want to do a differential step transient (say 200mV step), apply Vip = 400mV (CM) --> 500mV and Vin = 400mV (CM) --> 300mV.
Regarding to how to set input/output VCM. Usually input VCM is decided by its previous stage. You got the spec from system, and design your amplifier basing on this. (There are also applications you need to design input common mode feedback circuit to fix your VCM, if it is used in a differential TIA. )
Output VCM is set by your output CMFB circuit. The value is usually decided what your amplifier is going to drive, and of course you have to make sure output stage is happy working at fully tilted cases.
-Frank
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