What circuit is used for FM demodulation?

The FM demodulator is done with the help of a circuit called Phase Locked Loop (PLL). A PLL should have basic functional blocks like Voltage Controlled Oscillator (VCO), Phase comparator, Low Pass Filter (LPF) and Source follower.

How PLL can be used as FM demodulator?

To look at the operation of the PLL FM demodulator take the condition where no modulation is applied and the carrier is in the centre position of the pass-band the voltage on the tune line to the VCO is set to the mid position. However if the carrier deviates in frequency, the loop will try to keep the loop in lock.

How FM is generated through PLL?

A modulating signal is injected into the phase locked loop which causes the voltage controlled oscillator to momentarily change frequency until the output of the phase detector changes enough to balance the modulating signal. This proposed system overcomes the stability problems of direct FM modulation technique.

What is PLL FM?

(Phase-Locked Loop) An electronic circuit that compares an input frequency and phase to a reference signal. For example, in a superheterodyne FM radio, a PLL is used to lock the local oscillator to an accurate frequency reference such as a crystal or ceramic resonator.

When a PLL is used as an FM demodulator the demodulated signal appears at?

The demodulated FM signal is nothing but the control signal, which is available at pin number 7. Therefore, the signal available at pin number 7 is the required modulating signal.

Why is PLL required in receiver circuits?

A PLL may be used to synchronously demodulate amplitude modulated (AM) signals. The PLL recovers the phase and frequency of the incoming AM signal’s carrier. The recovered phase at the VCO differs from the carrier’s by 90°, so it is shifted in phase to match, and then fed to a multiplier.

How a PLL demodulate an FM signal?

How do you create a frequency modulation?

FM signals can be generated either by using direct frequency modulation, which is achieved by inputting a message directly into a voltage-controlled oscillator, or by using indirect frequency modulation, which is achieved by integrating a message signal to generate a phase-modulated signal, which is then used to …