The Old "Feedback Is Bad" Lie
Chris Hornbeck wrote:
Randy Yates wrote:
In the past we were told that negative feedback in an amplifier (power
amplifier) was bad. I believe the old charge was that it produced
excessive "transient intermodulation distortion."
Can someone please explain, using as much engineering-speak as necessary
(i.e., don't sugar-coat it - assume an audience of electrical engineers)
what this was all about?
The classic 1970's description went: an amplifier is modelled
as an input transconductance stage driving a capacitor, the
value determined by what's necessary for single dominant pole
stability, a big-ass gain stage, and followers.
YUK !
Things have improved somewhat since then.
Graham
|