If by "operate" you mean full rail-rail swing and 500MHz
toggle rate with a usefully small input overdrive, that's
going to want some exotic technology. Says to me that
your GBW product ought to be about 50GHz (figuring
you'd like less than 1% input gain error so A=100 at
speed).
Now the more input error you can tolerate, the lower
the GBW can be.
I think if this is achievable at all, it will be a cascade
of high bandwidth, low gain stages and perhaps a
clocked (sampling) regenerative design with some power
gating away from the sampling edge. Otherwise you'll
be driving things real hard and hot.
Now ask yourself this - is 500MHz a sampling clock rate,
or the bandwidth of the input signal that you must
compare with some (and how much?) accuracy?