Envelope Detector: An Envelope Detector is an electronic circuit that takes a high frequency signal as input and provides an output which is as “envelopes”of the original signal. The capacitor in the circuit stores up charge on 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. Most practical envelope detectors use either half –wave or full wave rectification of the signal to convert the AC audio into a pulsed DC signal. Filtering is then used to smooth the final result .This filtering is rarely perfect and some “ripple” is likely to remain on the envelope follower output More filtering gives a smoother result, but decreases the responsiveness thus, real-world designs must be optimized for the application.