In one of our designs, we used an AD7767 ADC, with its IN+ input tied to AGND and IN- tied to the Input from an Op-amp buffer. We are getting erratic converted values from the converter. There is a lot of noise and input kick-back. Besides that the converter is converting values above 3V OK. Whatever is falling below that is converted in an erratic manner. A Sample Capture of the output is attached herewith.
My question is, if we drive the ADC as mentioned above, with its positive terminal connected to AGND and an input signal of Swing 0 to 5V (5V is my ADC VREF) applied at its IN- input, will the ADC work as a single ended ADC, or is it compulsory that the ADC be driven differentially ?
Any inputs on this matter will be deeply appreciated.