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Hi,

This is the circuit of AD7606, input signal is ac coupled to the analog input pin of the ADC. As the datasheet mentioned, input resistance is matched on the analog input pin.

But now, an issue appears, the output code is incorrect. If there is no input signal, about 2V DC signal appears at the Vx Pin that can be measured by the multimeter.

This is also mentioned by the below link:

https://ez.analog.com/data_converters/precision_adcs/w/documents/3175/float-the-input-of-ad7606.

So is there any problems with this design? How to remove the floating voltage on the analog input pin and ensure the output code is correct?

Would you please give me some suggestions or a reference design?

Thanks!