I am trying to make 10Mohm of input impedance into a ADC (CS5530). I am planing to use differential input buffer to ADC so I am trying to use TI's document as reference. I tried the one differential in differential out single supply and dual supply. But I am not getting decent signal out of buffer (I am using sinus signal).
Basically I am trying them without ADC putting signal in and look them out with scope. I can't see sine signal out.
I am confused about GND levels I mean I should buffer GND level of signal generator and if it is big from other GND then opamp may broken or may stuck on rail limit. Circuit must consider voltage difference between 2 inputs.
Any suggestion is appreciated about getting 10M input impedance.
Schematic is as follows:
ADC: planing to use CS5530
opamp : LT1013
circuit built on breadboard