A Schmitt trigger is a type of electronic circuit that is commonly used to convert an input signal with varying voltage levels into a binary digital output signal with well-defined high and low voltage levels. It is named after its inventor, Otto H. Schmitt. The key feature of a Schmitt trigger is its hysteresis, which means that it has two different threshold voltage levels for rising and falling input signals. This hysteresis prevents rapid switching of the output when the input signal is near the threshold, reducing the effects of noise and providing more stable switching behavior.
The basic operation of a Schmitt trigger involves comparing the input voltage to two threshold voltages, typically referred to as the upper threshold (VUT) and lower threshold (VLT). The circuit produces a high output voltage (typically the positive supply voltage level, denoted as Vcc) when the input voltage rises above the upper threshold, and it produces a low output voltage (typically close to the ground or 0V, denoted as GND) when the input voltage falls below the lower threshold.
The use of a Schmitt trigger in signal conditioning is particularly beneficial in scenarios where the input signal is subject to noise, fluctuations, or other disturbances. Its hysteresis property ensures that the output doesn't switch rapidly between high and low states when the input signal is near the threshold, reducing false triggers caused by noise. This makes the Schmitt trigger an effective tool for cleaning up and stabilizing input signals, resulting in a more reliable digital output signal.
In essence, a Schmitt trigger is employed in signal conditioning to shape and adapt input signals to ensure accurate and consistent switching behavior. It's commonly used in applications such as debouncing mechanical switches (to prevent multiple false readings when a switch is pressed), level detection in digital systems, voltage level shifting, and noise rejection in various electronic circuits.