Oszillators

An oscillator is a system that produces a repeating variation around an equilibrium point, yielding a periodic signal or motion without a continuous external input. Oscillations are characterized by frequency, amplitude, and phase, and they may be sinusoidal or nonlinear in shape.

In electronics, oscillators generate periodic electrical signals used for timing, clock generation, and signal synthesis. They rely on feedback that sustains positive gain at a chosen frequency. The Barkhausen criterion states that sustained oscillations occur when the loop gain is unity and the total phase shift around the loop is a multiple of 360 degrees. Common topologies include LC oscillators, which use inductors and capacitors for high-frequency operation; RC oscillators for lower frequencies; and crystal oscillators, which employ piezoelectric quartz for high stability. Relaxation oscillators, built with nonlinear devices such as Schmitt triggers or comparators, produce non-sinusoidal waveforms like square or triangle waves.

Oscillators also appear in mechanical, biological, and chemical systems. Mechanical examples include pendulums and mass–spring setups, where restoring forces drive periodic motion. Biological oscillators underpin circadian rhythms and neuronal activity cycles. In music and audio technology, electronic oscillators generate waveforms that form the basis of tones and timbres in synthesizers and effects units.

Frequency stability depends on component quality, temperature, and power supply, with techniques such as crystal references, temperature compensation, and phase-locked loops used to maintain precise frequencies. Mathematical models describe oscillators with differential equations; linearized forms yield sinusoidal solutions near steady state.