Stan,

  First it would help to know more about the application? Are you
putting the ADC in the middle of 1,000,000 noisy gates? Or is it
standalone? Also why does your Pipeline ADC macro have only one
ground? Wouldn't it be better to separate the grounds into analog and
digital to prevent crosstalk? Does all your digital logic run off the
same supplies as the analog or is there high and low voltage digital,
that is do you need three ground lines analog, high voltage digital,
and low voltage digital? When the design was simulated was it simulated
with package parasitics? If not probably need to do this simulation to
understand how to partition the power supllies.

                                                                       Best Regards,

                                                                          Sheldon