Explain the advantages of employing negative feedback in explain the advantages of employing negative feedback in amplifiers
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Negative feedback opposes or subtracts from the input signals giving it many advantages in the design and stabilisation of control systems. For example, if the systems output changes for any reason, then negative feedback affects the input in such a way as to counteract the change.
The circuit represents a system with positive gain, G and feedback, β. The summing junction at its input subtracts the feedback signal from the input signal to form the error signal Vin - βG, which drives the system.
Then using the basic closed-loop circuit above we can derive the general feedback equation as being:
Negative Feedback Equation
We see that the effect of the negative feedback is to reduce the gain by the factor of: 1 + βG. This factor is called the “feedback factor” or “amount of feedback” and is often specified in decibels (dB) by the relationship of 20 log (1+ βG).
The circuit represents a system with positive gain, G and feedback, β. The summing junction at its input subtracts the feedback signal from the input signal to form the error signal Vin - βG, which drives the system.
Then using the basic closed-loop circuit above we can derive the general feedback equation as being:
Negative Feedback Equation
We see that the effect of the negative feedback is to reduce the gain by the factor of: 1 + βG. This factor is called the “feedback factor” or “amount of feedback” and is often specified in decibels (dB) by the relationship of 20 log (1+ βG).
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