AD73322: Vref transfer function

Document created by analog-archivist Employee on Feb 23, 2016
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Are the Vref directly connected to internal non inverting input of the op, or
this is an principle schematic  and the output op signal are only biased with 
In other word is the transfer function of the input stage :

a)Vout= -Vin + 2Vref    

OR ?

b)Vout= -Vin +Vref.

Have you more details about input encoder and output decoder stages about the
Vref biasing?


The input op amps on the AD73322 are accurately described by the diagram e.g.
figure 30. If you were to dc-couple the inputs to the AD73322 you would
theoretically get

Vout = -Vin + Vin*(1+Rf/Rin)

Therefore, if the bias level of the input signal is not Vref, but some other
level, then the signal should be ac-coupled prior to the input resistor.
Otherwise, the internal bias of the signal chain will be upset and clipping etc
will happen. The inverting input of the op amp is capable of self-biasing
itself at Vref, so you don't need to set the bias voltage to Vref externally,
after the AC coupling capacitor.

The output stage provides outputs that are biased around Vref.