What is the primary function of a Schmitt trigger?

The primary function of a Schmitt trigger is to convert a noisy input signal into a clean digital output. This device is designed to provide hysteresis in its input-output characteristics, which means it introduces different threshold voltages for rising and falling signal transitions. When a noisy analog signal crosses these thresholds, the Schmitt trigger produces a sharp transition to a stable high or low digital state. This characteristic is particularly useful in digital circuits where a clean, stable signal is necessary to prevent erratic behavior caused by noise or fluctuations in the input signal.

For example, if you have a signal that fluctuates around a certain voltage level, the Schmitt trigger ensures that once the signal rises above the upper threshold, the output will switch to a high state and remain there until the input drops below the lower threshold, regardless of any minor noise or variations in the input. This results in a clear and defined output, eliminating the ambiguity that can occur when signals are noisy or have slow transition times.