电子振荡器（英语：electronic oscillator）是用来产生具有周期性的模拟信号（通常是正弦波或方波）的电子电路。 通常由放大电路、选频网络、正反馈网络和稳幅环节组成。振荡器将电源提供的直流（DC）转变成交流信号。它们被广泛应用于许多电子设备中。由振荡器产生信号的常见例子有无线电和电视发射机广播的信号，调节计算机和石英钟的时钟信号，和电子传呼机和电子游戏发出的声音。

振荡器通常用他们输出信号的频率描述：

用来由直流电源产生高功率交流输出的振荡器通常称为逆变器。

振荡器主要可以分成以下两种：谐波振荡器（harmonic oscillator）与弛张振荡器（relaxation oscillator）。

An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave. Oscillators convert direct current (DC) from a power supply to an alternating current (AC) signal. They are widely used in many electronic devices. Common examples of signals generated by oscillators include signals broadcast by radio and television transmitters, clock signals that regulate computers and quartz clocks, and the sounds produced by electronic beepers and video games.