You need the seperate your circuit blocks into agressors and victims. Since the comparator
decision might be influence by spikes on the supply I usually connect the comparator to
the analog supply (and provide local decoupling to avoid switching noise propagate through
the circuit).
The pad-ring is usually splited in an analog and a digital section (or even more sections
for larger chips). However, if you don't want to split the pad-ring you can still supply the
pad-ring with a seperate supply and provide analog and digital supply directly to the core.

Hope this helps, regards.

For good decoupling you should put a resistor between the sensitive supply and
your comparator supply (the resistors decouples the two circuits). However, often
the speed of the comparator is critical and one cannot tolerate any voltage drop
over a resistor.
Therefore I recommenend to add only capacitance between vdd and gnd. Make
sure that the capacitance is close to the source (in order to keep the switching
noise localy). The capacitance value will depend on your comparator.

Regards