Question
How does a diode envelope detector function?
Answer Options
- A) By rectification and filtering of RF signals
- B) By breakdown of the Zener voltage
- C) By mixing signals with noise in the transition region of the diode
- D) By sensing the change of reactance in the diode with respect to frequency
Correct Answer: A
Explanation
A diode envelope detector is the classic circuit used in \text{AM} receivers to recover the audio signal from the modulated \text{RF} carrier. It functions by converting the varying \text{RF} signal into a usable, varying \text{DC} voltage that tracks the original audio envelope.
The diode envelope detector functions by rectification and filtering of \text{RF} signals. The diode acts as a half-wave rectifier, removing one half of the \text{RF} waveform. The resulting pulsed \text{DC} signal, which follows the audio envelope, is then smoothed by a small capacitor (a simple low-pass filter) to recover the original baseband audio signal.
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