I) What do you understand by feedback in amplifiers? ii) What are the types of feedback? What are the advantages and disadvantages of negative feedback?

Q.) i) What do you understand by feedback in amplifiers? ii) What are the types of feedback? What are the advantages and disadvantages of negative feedback?

 Subject: Electronic Devices and Circuit

i) Feedback in Amplifiers:

Feedback in amplifiers is a process of feeding a portion of the output signal back to the input of the amplifier. This feedback signal can be either positive or negative, depending on the phase relationship between the input and output signals.

ii) Types of Feedback:

There are two main types of feedback:

  1. Positive Feedback: In positive feedback, the feedback signal is in phase with the input signal. This means that the output signal is amplified by the feedback signal, resulting in a higher overall gain. Positive feedback is often used in oscillators to create sustained oscillations.

  2. Negative Feedback: In negative feedback, the feedback signal is out of phase with the input signal. This means that the output signal is reduced by the feedback signal, resulting in a lower overall gain. Negative feedback is often used in amplifiers to reduce distortion and improve stability.

Advantages and Disadvantages of Negative Feedback:

Advantages:

  • Reduced Distortion: Negative feedback reduces distortion by canceling out the nonlinear components of the amplifier's output signal. This results in a cleaner and more accurate output signal.
  • Improved Stability: Negative feedback improves stability by reducing the amplifier's sensitivity to changes in component values and temperature. This makes the amplifier more reliable and less likely to oscillate.
  • Increased Bandwidth: Negative feedback can increase the amplifier's bandwidth by reducing the effects of parasitic capacitances and inductances. This results in a wider range of frequencies that the amplifier can amplify.

Disadvantages:

  • Reduced Gain: Negative feedback reduces the amplifier's overall gain. This is because the feedback signal subtracts from the input signal, resulting in a lower output signal.
  • Increased Noise: Negative feedback can increase the amplifier's noise figure. This is because the feedback signal also amplifies the noise present in the output signal.
  • Reduced Slew Rate: Negative feedback can reduce the amplifier's slew rate. This is because the feedback signal slows down the response time of the amplifier.