Question

With help of circuit diagram. Explain the working of a junction diode as an amplitude demodulator?

Answer 1

Hint: Demodulation the name suggests is the reverse process of modulation. The process of recovering audio frequency signals from the modulated carrier wave is called detector or demodulation. In a demodulator a high frequency wave is filtered to get the desired signal. For this a capacitance is used in parallel which helps in filtering the high frequency component of the imported modulated wave.


Complete step-by-step solution:
The diode detector is the simplest and basic form of amplitude modulator. AM signal detector and it detects the envelope of the AM signal. The AM diode detector is an envelope detector that provides an output of the envelope of the signal.as such the diode detector or demodulator is able to provide an output proportional to the amplitude of the amplitude modulated signal.

Junction diode as the amplitude modulator operates by detecting the envelope of the incoming signal which it does by rectifying the signal. Current is allowed to flow through the diode in only one direction, giving either the positive or negative half of the envelope at the output.

Note: The AM detector or demodulator includes a capacitor at the output; its purpose is to remove any radio frequency components of the signal at the output. The value is chosen so that it does not affect the audio base-signal. There is also a leakage path to enable the capacitor to discharge, but this may be provided by the circuit into which the demodulator is connected.