R u working with MOS only or BiCMOS?
The way I saw is to isolate is to aploy level shifter atleast at two levels...1. when you are coupling from pre-amp to latch...use one level shifter..this helps....and reduce/protect upto some extent the pre-amp from the unwanted forced signal distortion.....2. at the input of pre-amp...use another level shifter....this pretocet the very input of the comparator from the above distortion........
If your accuracy requirement is not too high (>=4/5mV)...you also could go for two-stage pre-amp...which itself very rugged...but definitely power and area is sacrificed.....
....one more good topology to prevent kickback noise (may not be too 'to the point' for u) is the re-configuration of the latch where from the kick back noise got generated....the references are...1. Johns Martin book (only Idea)....2.JSSC..Jensen....16GHz HBT comp....Sep-2003