A comparator consists of a specialized high-gain differential amplifier. They are commonly used in devices that measure and digitize analog signals, such as successive-approximation ADCs, as well as relaxation oscillators.

What circuits use comparators?

Op-amp window comparators are a type of voltage comparator circuit which uses two op- amp comparators to produce a two-state output that indicates whether or not the input voltage is within a particular range or window of values by using two reference voltages. An upper reference voltage and a lower reference voltage.

What's the purpose of a comparator?

A comparator is used to compare a measurable quantity with a reference or standard such as two voltages or currents. It outputs a digital signal showing the results.