Hi Lorime,
When connecting the PD or RESET, the signal attenuates. Was there any part or device connected to this pins that might add the load when connecting it with the ADAS3023?
The output of the ADC is only showing the positive side. What is the source of the Sine wave signal? Was the source terminated properly? and What is the source impedance? Please try to inout a DC voltage to verify of the ADC is converting properly on DC.
Please also share the schematic of your ARM board.
Regards,
Jonathan