A Schmitt trigger is a type of electronic circuit that converts an input signal into a digital output signal. It is used to provide hysteresis in a circuit, which means it introduces two different threshold voltage levels for rising and falling input signals. This characteristic makes the Schmitt trigger particularly useful in applications where noise or fluctuations in the input signal might cause false triggering in standard comparator circuits.
The Schmitt trigger has two distinct voltage threshold levels, commonly referred to as the upper threshold (Vhigh) and the lower threshold (Vlow). When the input signal rises above Vhigh, the output switches to a high state (usually representing a digital '1'). Conversely, when the input signal falls below Vlow, the output switches to a low state (representing a digital '0'). The output remains in its current state as long as the input signal remains between Vhigh and Vlow.
The hysteresis property of the Schmitt trigger ensures that small changes in the input signal near the switching thresholds do not cause rapid toggling of the output, thus providing noise immunity and stability. This is in contrast to standard comparators, which may oscillate between their output states when the input signal hovers around the threshold voltage level.
Schmitt triggers find applications in various electronic circuits, including signal conditioning, debounce circuits, relaxation oscillators, and noise filtering. They are often used in digital electronics, communication systems, and control systems to ensure reliable and robust signal processing.