Subject: Re: Historical question: negative feedback and the op amp
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Date: Wed, 13 Nov 2002 16:39:13 GMT
NNTP-Posting-Date: Wed, 13 Nov 2002 11:39:13 EST
Organization: Cox Communications
"Ban" wrote in message
> "Mike" schrieb im Newsbeitrag
> Feedback in itself is more a cure for the unlinearity and other
> shortcomings, nowadays it is no more needed, digital circuits work so
> precise, they do not require feedback. Feedback is an antique thing, it
> wasts power and a *lot* of speed. It is just a crutch not something we
> should cherish.
Hmmm... I can't think of any way to build a PLL equivalent that doesn't use
feedback, whether it's analog or digital. Without that "crutch," your disk
drive won't spin at the correct speed, and you won't be able to recover data
from it. Your cell phone won't work, because the receiver won't be able to
track the incoming signal. Even your land based telephone won't work,
because nothing will be able to recieve the SONET/SDH signal at the other
end. Your computer network won't work at all. Digital won't help you, no
matter how accurate it is: you have to be able to track another signal, and
to do that, I'm not aware of any mechanism besides feedback. Are you?
Speaking of analog vs digital, virtually every communication channel,
whether it's a disk drive or a cell phone or a network link or a DSL or
cable modem, winds up with an analog signal at the receiver, and often at
the transmitter as well. Even many of the digital signals blasted across
your motherboard are best thought of as analog.
You might think analog is dead, but I find it to be a remarkably rich and
fertile place for innovation and invention.
-- Mike --