Hi, I am designing an ADC board using AD7699. We worked with the EVM board of the same product. The first problem we have is the buffer OPAMP selection.In the reference design ADA4841 is used. We need a single supply, unity gain stable and low noise low, THD buffer. (In fact when we used single-ended input with VREF=2V, and the 4841 -Vcc=0, we have substantial nonlinearity. ). Which OPAMP would you recommend for us? The second problem is about grounding. We have significant noise due to grounding. What is the best practice for decreasing noise in our case?