Assertion (A): A large negative feedback is deliberately introduced i...
Assertion (A): A large negative feedback is deliberately introduced in an amplifier to make its gain independent of variation in parameters of the active device.
Reason (R): A large negative value of feedback results in a high value of return difference compared to unity, which makes the feedback gain inversely proportional to the feedback factor.
Explanation:
The given assertion and reason both are correct, and the reason is a correct explanation of the assertion.
Introduction to Feedback:
Feedback is a process in which a portion of the output signal of a system is fed back to the input, thereby altering the overall system response. In an amplifier, feedback is commonly used to improve its performance.
Understanding the Assertion:
The assertion states that a large negative feedback is deliberately introduced in an amplifier to make its gain independent of variation in parameters of the active device. This means that by applying negative feedback, the amplifier's gain can be made more stable, regardless of any variations in the active device's parameters such as temperature, aging, or manufacturing tolerances.
Understanding the Reason:
The reason provided explains why a large negative value of feedback is used. It states that a high value of return difference, which is the difference between the input and the feedback signal, compared to unity (1), makes the feedback gain inversely proportional to the feedback factor. In other words, as the feedback factor increases, the feedback gain decreases. This inverse relationship helps to stabilize the overall gain of the amplifier.
Benefits of Negative Feedback:
Negative feedback has several benefits in amplifier design:
1. Stability: By reducing the gain variations caused by changes in the active device's parameters, negative feedback improves the stability of an amplifier.
2. Linearity: Negative feedback reduces distortion in the amplifier, resulting in improved linearity of the output signal.
3. Bandwidth: Negative feedback can increase the bandwidth of an amplifier, allowing it to handle a wider range of frequencies.
4. Noise reduction: Negative feedback can reduce the noise introduced by the active device, resulting in a cleaner output signal.
Conclusion:
In conclusion, the assertion and reason are both correct. A large negative feedback is deliberately introduced in an amplifier to make its gain independent of variation in parameters of the active device. The reason provided explains that a high value of return difference compared to unity makes the feedback gain inversely proportional to the feedback factor, which helps in achieving a stable amplifier gain.
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