Hello, after reading the specifications of AD7766 I want to ask about Section: Theory of Operation, Analog Input Structure page 16.

It is said that

"The value of C1 is dominated by the pin capacitance. RIN is typically 1.4 kΩ, the lumped component of serial resistors and the RON of the switches. C2 is typically 22 pF, and its value is dominated by the sampling capacitor."

I need to know the value of sampling capacitor in order to calculate Tau of sinc filter so I can design my system not to perform amplitude errors because sampling too fast.

Hi valhogaard,

May I ask what frequency range you are using? We can derive the value from there. What you can do is try the mathematical approach.

I recommend this thread http://ez.analog.com/message/25508#25508. discussing importance of input impedance and graphs showing that measured and mathematical approach have similar results.

regards,

Bing