Re: comparator
here is a short description, but you need to be more specific:
a nominally analog differencing circuit, that may be operated in synchrony with a clock or asynchronously, incorporating sufficient gain to force the output signal into saturation. Such circuits are typically used to provide one or more of three indications, X>Y, X<Y or X=Y. By using multiple individual comparators in logic circuits, significant characterization of a large group of input signals can be provided.