I am trying to use EVAL-AD7982-PMDZ to digitize voltage signals from a capacitive amplifier. I want the input impedances of the input signal ports to be high (~1 MOhm). However, in EVAL-AD7982-PMDZ, there are bypass capacitors (C2, C3, C5) and a bypass resistor (R4) between the input signal port and the ground, which makes the input impedance to be a few hundred Ohms. I am wondering what is the purpose of these bypass resistors and bypass capacitors and how I can make the input impedance to be high.
Thank you.