I have a unity gain buffer that is AC coupled. on the input and the output. I am sort of confused. Do I need to add a DC bias anywhere? If there is a cap on the input and the output, what is the bias? I ask because the opamp I am using (OPA564) says that I need to make sure that the Vin+ and Vin- need to have a differential below .5V at all times if used as a buffer.