Comparators

A comparator is a device or algorithm that determines the relative order of two inputs and outputs a signal indicating which input is greater. In electronics, a comparator typically compares two analog voltages and produces a binary output that reflects whether the non-inverting input is higher than the inverting input.

Electronic comparators usually have a high-gain differential input stage and an output stage that can be push-pull or open-collector. Open-collector outputs require a pull-up resistor. Important specifications include input offset voltage, input bias current, common-mode input range, propagation delay, and whether the device includes hysteresis to prevent rapid switching near the threshold.

Common applications include level detection and thresholding, zero-cross detection, window comparators (to detect whether a signal lies within a specified range), trigger generation for PWM and switching regulators, and front ends for analog-to-digital converters. Variants include window comparators, programmable or adjustable hysteresis, and latched or memory-type comparators that hold their output after a threshold is crossed.

Practical considerations include the choice between dedicated comparators and using op-amps as comparators, the potential for output saturation and slow recovery, noise sensitivity near the threshold, and the need for proper hysteresis or filtering in noisy environments. Classic examples of comparator ICs are the LM311, LM393, and LM339 families, each with differing output configurations and performance.

In software, a comparator refers to a function, object, or key that defines an ordering on values, enabling sorting, searching, and ordered data structures. The concept serves as a general framework across hardware and software domains.