ADCMP572 input biasing

We are having trouble getting the ADCMP572 to receive a 400mVppdiff signal running at 2.7Ghz without disturbing the serial link it is attached to (see attached diagram).

Questions about ADCMP572 input:

1) What DC bias do inputs want to

operate in middle of CMR?

2) What is Vinmin?

3) What is the structure of the input?