From: "Peter O. Brackett"
Subject: Re: Historical question: negative feedback and the op amp
Date: Wed, 13 Nov 2002 11:45:27 -0500
Organization: MindSpring Enterprises
X-Server-Date: 13 Nov 2002 16:45:29 GMT
X-Newsreader: Microsoft Outlook Express 5.00.2919.6600
As Kevin has pointed out, feedback is beneficial for both analog *and*
Because of the extreme secrecy surrounding it, most have not yet heard of
patented digital op-amp [DOA] concept.
What about the *digital op-amp* or DOA? It's the greatest idea in digital
since the invention of the all pervasive wavelets or the widely used
The digital op-amp [DOA] is simply a digital multiplier with a very large
DOA works best in a twos complement number system, wherein the fact that it
even saturate, rather it rolls from rail to rail so to speak, can be used to
With the DOA, the need for multiplier precision and accuracy in the
is reduced and controlled almost entirely by the elements in the feedback
path. This saves
many digits of precision needed for accuracy of response in conventional DSP
Saves power, results in faster response, etc...
Currently only the inventor and his licencees can use the DOA concept until
expires in 2011.
I have developed several personal use projects utilizing the DOA concept,
but with current
standard DSP chips, i.e. TMS, 56K, Sharc, Zoran, PinOak, etc... the number
of digits in
the multiplier are fixed and so the DOA advantages are applicable only to
specific DSP area, where one synthsizes the DSP engines directly in Silicon.
the power reductions possible make it very attractive for mobile
Indialantic By-the-Sea, FL.
"carltons" wrote in message
> In article , "Kevin Aylward"
> > "Ban" wrote in message
> > news:D7pA9.email@example.com...
> > > "Mike" schrieb im Newsbeitrag
> > > news:hBnA9.5273$XF5.firstname.lastname@example.org...
> > > > Harold Black came up with his negative feedback theory in 1927, yet
> > the
> > > > first op-amp wasn't invented until the 1950s.
> > > >
> > > > The op-amp seems like such a natural extension, once you know about
> > > negative
> > > > feedback. Why did it take so long for the op-amp to come along?
> > > >
> > > > -- Mike --
> > > >
> > > >
> > >
> > > I do not think OpAmps come from the negative feedback idea, nearly
> > every
> > > electronic circuit has been using feedback since the beginning of the
> > tube
> > > aera.
> > >
> > > Rather the main idea is to combine a functional block in one unit,
> > which
> > > requires some kind of integration.
> > >
> > > Feedback in itself is more a cure for the unlinearity and other
> > > shortcomings, nowadays it is no more needed,
> > Jesus wept dude. How you can claim this is pretty amazing really.
> > Feedback is most certainly a very usefull device, and imo, will *always*
> > be used.
> > > digital circuits work so
> > > precise, they do not require feedback.
> > But digital systems still use feedback, e.g. digital filters. Feedback
> > control systems are indispensable, analog or digital based. Without a
> > feedback temperature control system you would be dead.
> > >Feedback is an antique thing,
> > Sure is, so is the wheel.
> > >it
> > > wasts power and a *lot* of speed. It is just a crutch not something we
> > > should cherish.
> > I don't why you say this. Sure using analogue feedback has some
> > negatives, but in most cases the advantages easily outweigh the
> > disadvantages. Try and make a reliable fixed gain of 100 without
> > feedback. This whole concept is not even debatable. Feedback is one of
> > the most important pieces of science around.
> > Kevin Aylward
> > email@example.com
> > http://www.anasoft.co.uk
> > SuperSpice, a very affordable Mixed-Mode
> > Windows Simulator with Schematic Capture,
> I have a feeling that this thread will go off into the troposphere soon
> due to conservation of misery. Feedback, linearity, etc. are all
> important and will have to be thrown into the equation for a system.
> Whether done with digital circuits or analogue you will arrive at the same
> spot, no matter what. Whether you believe in analogue or digital, first
> look at the equations. For instance, you don't get infinite slopes on the
> side of a filter without the filter having infinite group delay and
> passband ripple. The circuit implementation is unimportant. Ice cream
> melts when it's 60 degrees celsius outside no matter how much you don't
> want it to or how frozen you get it is before you put it out. Putting on
> a happy face still gives you melted cream without the ice. God's laws
> will always apply.
> If this was a digital world, wouldn't we have no colours? Wouldn't we
> have to goose step everywhere and either in a forward or backward
> direction? ETC,ETC, :-)
> Steve WB4CZR