A relaxation oscillator (in English: Relaxation Oscillator, abbreviated as ROSC), also known as a re-oscillator, is an electronic circuit that generates non-sinusoidal wave signals (such as square waves, triangular waves, and sawtooth waves) through the periodic charging and discharging of energy storage components. Its core consists of single-crystal transistors, resistors, capacitors, etc., and achieves self-oscillation through the threshold switching mechanism of nonlinear components. It is mainly applied in timers, function generators, digital circuit clock sources, and capacitance sensors, etc. [1-2] [6-7].
The relaxation oscillator forms an RC time constant to control the frequency by charging and discharging the capacitor through resistors. The threshold voltage is set by a resistor network. When the capacitor charges to the high threshold level, it is quickly discharged through a switching element, and the waveform shows a steep jump characteristic, such as the positive sharp pulse output at the R7 terminal [1-2]. The output frequency can be adjusted by regulating the threshold voltage or the RC parameters. The temperature compensation scheme can reduce frequency drift by setting a negative temperature coefficient threshold [3] [5]. The typical circuit structures include Schmitt trigger RC circuits, NE555 timers, and dual-transistor multivibrators. They are all applied in PWM power supplies, clock circuits, and biomedical signal processing [4] [6-7].