I have a question from our customer about input impedance for analog inputs of AD9269.
We need the equivalent input impedance of ADC when we consider the anti-alias filter.
Attached figure is from AN-742.
The input capacitance is indicated in the datasheet and it is 6.5pF.
(This value is refer to GND then we need to double it for differential circuit)
I'd like to know the resistance "Ri" between VIN+ and VIN-.
Could you tell me the resistance ?