feedback, negative feedback, Advantages of Negative Feedback
What is feedback?
Taking a portion of the signal arriving at the load and feeding it back to the input.
What is negative feedback?
Adding the feedback signal to the input so as to partially cancel the input signal to the amplifier.
Doesn’t this reduce the gain?
Yes, this is the price we pay for using feedback.
Why use feedback?
Provides a series of benefits, such as improved bandwidth, that outweigh the costs in lost gain and increased complexity in amplifier design.
Advantages of Negative Feedback
Gain desensitivity - less variation in amplifier gain with changes in (current gain) of transistors due to dc bias, temperature, fabrication process variations, etc.
Bandwidth extension - extends dominant high and low frequency poles to higher and lower frequencies, respectively.
Noise reduction - improves signal-to-noise ratio
Improves amplifier linearity - reduces distortion in signal due to gain variations due to transistors
Cost of these advantages:
Loss of gain, may require an added gain stage to compensate.
Added complexity in design