By using the positive feedback in the process of Schmidt trigger state transition, the periodic signal with slow edge change can be transformed into a rectangular pulse signal with steep edge. As long as the amplitude of the input signal is greater than vt+, a rectangular pulse signal with the same frequency can be obtained at the output of Schmidt trigger.

When pulse signals with different and irregular amplitudes are added to the input end of Schmidt trigger, the pulse signal with amplitude greater than the expected value can be selected for output.

Extended data:

Sine wave is a signal with a single frequency component, so it is named because its waveform is sinusoidal in mathematics. Any complex signal, such as music signal, can be regarded as a composite of many sine waves with different frequencies and sizes.

Different from amplifier circuit, self-excited oscillation circuit is an electronic circuit that can generate its own output signal without external signal. Therefore, it is often used as a signal generator to generate signals of various frequencies. Oscillating circuit is divided into sine wave oscillator and non-sine wave oscillator.

Square wave is a non-sine wave, which usually appears in electronics and signal processing. An ideal square wave has only two values: high and low. A signal with a rectangular waveform of current or voltage is a rectangular wave signal, and the ratio of the time occupied by high level in a waveform period is called duty cycle, which can also be understood as the ratio of the effective release time of the circuit to the total release time.

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