Discuss the effect of negative feedback on gain, input impedance and output impedance, distortion, stability.

Effect of Negative Feedback on Gain, Input Impedance, Output Impedance, Distortion, and Stability

Negative feedback is a technique used in amplifier circuits to reduce distortion, improve stability, and increase input impedance. It involves feeding a portion of the output signal back to the input in a way that opposes the original input signal. This feedback can be applied to a variety of amplifier types, including voltage amplifiers, current amplifiers, and power amplifiers.

Gain

The gain of an amplifier is the ratio of the output signal to the input signal. Negative feedback reduces the gain of an amplifier because it subtracts a portion of the output signal from the input signal. The amount of reduction in gain depends on the amount of feedback applied.

Input Impedance

The input impedance of an amplifier is the impedance seen looking into the input terminals. Negative feedback increases the input impedance of an amplifier because it effectively adds a resistor in parallel with the input terminals. The value of this resistor is equal to the feedback resistor.

Output Impedance

The output impedance of an amplifier is the impedance seen looking into the output terminals. Negative feedback decreases the output impedance of an amplifier because it effectively adds a resistor in series with the output terminals. The value of this resistor is equal to the feedback resistor.

Distortion

Distortion is the unwanted alteration of the input signal waveform by an amplifier. Negative feedback reduces distortion by canceling out nonlinearities in the amplifier. This is because the feedback signal is a faithful representation of the output signal, and it is subtracted from the input signal before it is amplified.

Stability

Stability refers to the ability of an amplifier to maintain a constant output signal in response to a constant input signal. Negative feedback improves stability by reducing the loop gain of the amplifier. The loop gain is the gain of the amplifier when the feedback loop is closed. A lower loop gain makes the amplifier less likely to oscillate or become unstable.

Conclusion

Negative feedback is a valuable technique used in amplifier circuits to reduce distortion, improve stability, and increase input impedance. However, it also reduces the gain of the amplifier and decreases the output impedance. The amount of feedback applied must be carefully chosen to achieve the desired results.