包络检波器（英语：envelope detector）是以高频信号为输入信号并提供原始信号的包络的一种电子线路。电路中的电容器会在上升沿充电，并在信号下降时通过电阻器缓慢释放电荷。串联的二极管将输入信号整流，只在正输入端比负输入端电位高的时候允许电流流过。

大多数实际的包络检波器使用半波或全波整流信号来转换交流音频输入到直流脉冲信号。然后用滤波来平滑最终结果。这种滤波是很少完美的，一些“纹波”会保持输出包络跟随，由其对于低频输入（如低音吉他的音符）。更多滤波会得到更平滑的结果，但会降低响应性；因此，实际的设计必须针对应用进行优化。

An envelope detector is an electronic circuit that takes a high-frequency signal as input and provides an output which is the envelope of the original signal. The capacitor in the circuit stores up charge on the rising edge, and releases it slowly through the resistor when the signal falls. The diode in series rectifies the incoming signal, allowing current flow only when the positive input terminal is at a higher potential than the negative input terminal.