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Negative feedback vs Positive feedback | Difference between Negative feedback and Positive feedback

This page compares Negative feedback vs Positive feedback and mentions difference between Negative feedback and Positive feedback in amplifiers. It mentions advantages and disadvantages of negative feedback over positive feedback.

As we know feedback is process in which part or portion of output signal is fed back to input port. It is used to control dynamic behaviour of the circuit or system.

positive Feedback vs Negative Feedback

There are two types of feedback in amplifier.
• Positive feedback
• Negative feedback

If original input signal and feedback signal are in phase, the feedback type is known as positive feedback. It tends to increase the output.

If original input signal and feedback signal are out of phase, the feedback type is known as negative feedback. It tends to reduce the output.

Depending upon sampling type and mixing networks, feedback amplifiers are categorized as follows.
• Voltage series feedback
• Current series feedback
• Current shunt feedback
• Voltage shunt feedback


Parameter Positive Feedback Negative Feedback
Overall phase shift 0 or 360 degrees 180 degrees
Input and output voltage, noise increases due to feedback Decreases due to feedback
Feedback signal and input signal In phase Out of phase
Gain increases decreases
Stability poor better
applications or use oscillators amplifiers

Advantages and disadvantages of negative feedback over positive feedback

Following are the advantages of negative feedback over positive feedback.
• Negative feedback stabilizes gain of amplifier.
• Input resistance increases for certain configurations.
• Output resistance decreases for certain configurations.
• Operating point is stabilized.
• The negative feedback is employed in various applications such as electronic amoplifiers, regulated power suplies, wideband amplifiers etc.

Following are the disadvantages of negative feedback over positive feedback.
• Reduction in gain
• Reduction in input resistance in case of current shunt and voltage shunt type amplifiers.
• Increase in output resistance in case of current series and current shunt feedback amplifiers.


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