1. In electronics, Schmidt trigger is a comparator circuit with positive feedback.

2. For standard Schmitt trigger, when the input voltage is higher than the forward threshold voltage, the output is high; When the input voltage is lower than the negative threshold voltage, the output is low; When the input is between positive and negative threshold voltages, the output is unchanged, that is, when the output changes from high level to low level or from low level to high level, the corresponding threshold voltages are different. Only when the input voltage changes sufficiently, the output will change, so this kind of element is named flip-flop. This double-threshold action is called hysteresis, which indicates that Schmidt trigger has memory. Essentially, Schmidt trigger is a kind of bistable multivibrator.

3. Schmidt trigger can be used as a waveform shaping circuit to shape the analog signal waveform into a square wave that can be processed by digital circuits. Moreover, because of its hysteresis characteristics, Schmidt trigger can be used for anti-jamming, and its applications include anti-jamming in open-loop configuration and realization of multivibrator in closed-loop positive feedback/negative feedback configuration.