The designation comparator already indicates that it is a device that compares values with each other.
- In analog circuitry, a comparator is a differential amplifier that compares an analog input signal with a comparison signal. In such an electronic circuit, a sufficiently large gain produces a square-wave output signal. The output level depends on whether the input signal is larger or smaller than the comparison signal. The comparison signal itself can be a fixed or adjustable voltage, or the signal from a sensor. For example, a photoresistor could be used to trigger the comparator at nightfall, as is the case with twilight switches. Comparator hysteresis of the comparator; the slope of the output signal can be further increased by feedback. Such comparator circuits with steep hysteresis are called Schmitt triggers and are used, among other things, in regenerators for the regeneration of ground pulse signals.
- In addition to analog comparators, there are also digital comparators.