Re: How to explain how negative feedback lowers noise?

Tom Lee

Yes, Black invented both feedforward and negative feedback amplifiers, the latter indeed on the Lackawanna ferry in that year. I'm not sure what oddity you were referring to.

But, negative feedback does not "minimize the added noise". I wish people would stop repeating this erroneous claim. I've already explained twice now why it's false. Widespread, perhaps, but false nonetheless.

And Groundhog day has already passed.


Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070

On 3/25/2021 19:22, pheilman wrote:
Odd, when I was in school we were taught that negative feedback amplifiers
were invented at Bell Labs. By Harold Black. In 1927, on the ferry.

All amplifiers add noise to the signal as it passes through, negative
feedback amplifiers minimize the added noise. The excess gain of the
amplifier is traded for lower noise and lower distortion.

Removing noise from the incoming signal is beyond the ability of an
amplifier, this is more in the realm of a filter.


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