Question
What is the purpose of neutralizing an amplifier?
Answer Options
- A) To limit the modulation index
- B) To eliminate self-oscillations
- C) To cut off the final amplifier during standby periods
- D) To keep the carrier on frequency
Correct Answer: B
Explanation
Neutralization is a process specifically applied to high-gain Radio Frequency (RF) amplifier stages, such as those using vacuum tubes or certain types of transistors. In these amplifiers, a small amount of the output signal can couple back to the input through stray capacitance, providing positive feedback.
If this feedback is strong enough, the amplifier will spontaneously generate its own signal, leading to unwanted parasitic oscillation. The purpose of neutralization is to inject a small, equal, and opposite phase signal back into the input, effectively cancelling the unwanted feedback path, thereby eliminating self-oscillations and ensuring stable, controlled amplification.
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