The correct sequence of subsystems in an FM receiver is:

Question

The correct sequence of subsystems in an FM receiver is:

1. A. Mixer → RF amplifier → limiter → IF amplifier → discriminator → audio amplifier
2. B. RF amplifier → mixer → limiter → discriminator → IF amplifier → audio amplifier
3. C. RF amplifier → mixer → IF amplifier → limiter → discriminator → audio amplifier (Correct answer)
4. D. Mixer → IF amplifier → limiter → audio amplifier → discriminator

Correct Answer

Option C — RF amplifier → mixer → IF amplifier → limiter → discriminator → audio amplifier

Detailed Solution & Explanation

The correct answer is RF amplifier → mixer → IF amplifier → limiter → discriminator → audio amplifier.

Key Points

• The correct order in a superheterodyne FM receiver is:

1. RF amplifier — amplifies the incoming signal and rejects the image frequency

2. Mixer — heterodynes it with the local oscillator down to the intermediate frequency

3. IF amplifier — supplies most of the receiver's gain and selectivity

4. Limiter — clips amplitude variations so that only frequency information remains

5. Discriminator — converts frequency variations back into the audio signal

6. Audio amplifier — drives the loudspeaker

• The limiter must precede the discriminator, since its whole purpose is to strip amplitude noise before demodulation.

Additional Information

• The standard IF for FM broadcast receivers is 10.7 MHz, against 455 kHz for AM receivers.
• The limiter stage is what gives FM its well-known noise immunity: noise rides mainly on amplitude, and the limiter removes it before any information is extracted.