Comparator

A comparator is a device or algorithm that compares two inputs and indicates their relative magnitude. In electronics, a comparator is an electronic circuit that compares two voltages or currents and outputs a digital signal showing which input is larger. They are used for level detection, waveform slicing, zero-crossing detection, and similar tasks. Analog comparators typically provide a binary output and may include features such as open-collector or push-pull outputs and input hysteresis to prevent chatter around the threshold. Key specifications include input range, common-mode range, propagation delay, and output type.

In hardware, common examples include voltage comparators such as the LM311 and LM393. Window comparators use two references to determine whether an input lies within a given range. Real-world applications include pulse-width modulation control, analog-to-digital conversion front ends, and safety or fault-detection circuits.

In software and computing, a comparator is a function or object that defines an ordering relationship between two elements. It enables sorting, searching, and ordered data structures by returning a negative, zero, or positive value to indicate the relative order. Language examples include Java’s Comparator interface, Python’s key functions and rich comparison methods, and C/C++ comparison functions used by qsort and sort. Important properties of a software comparator include a consistent, antisymmetric, and transitive ordering, and, depending on the context, whether the sort should be stable. The term thus covers both physical devices that compare signals and software routines that establish ordering among data.