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Re: Tektronix Cascomp and decendants

Posted by Steve Eddy on May 19, 2003 at 22:03:24

In Reply to: Tektronix Cascomp and decendants posted by jcox on May 19, 2003 at 20:53:03:

Quinn's US pat 4897611 is a differential transistor input stage linearization technique that compensates for thermal distortion, see patents that ref this one, including Graeme's 5053718

Yes. Though Quinn's work on this goes back more than a decade prior to his 4897611 patent (which by the way makes no specific mention of thermal distortion). Check out his 4146844 patent from 1977. The first two sentences from the background text are:

Two major sources of amplifier error are non-linearity and thermal distortion. The mechanisms which produce these undesirable traits are inherent in the fundamental physical properties of semiconductor pn junctions.

Of course these properties were well known well before 1977 and had been addressed by others before Quinn.

Which rather makes one just want to shake their head when they read stuff like this on the Lavardin website:

The memory distortion (1) of components is the greatest discovery in analog audio design over the last twenty years.

And worse, footnote (1):

(1) The memory distortion of components was discovered entirely by Lavardin Technologies engineers as are the procedure for measuring the very audible distortion which results from it.

Not to mention that they try to hide the fact that what they're talking about is thermal distortion by using marketing verbiage to make it seem as if they're talking about something entirely different:

Tube technology allows electrons to travel through a vacuum which causes no storage or memory effect, but solid-state amplifiers use silicon components which keeps the trace of electrons flux that have gone through.

Gotta love marketing (otherwise known as "research papers" to a certain someone here).

There are many more useful methods of linearizing transistor circuits than those "invented" by Lavardin

Certainly. As I said, Lavardin's approach is merely one of them.

se

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