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differential cascode patented in 2007

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pieter t

Disabled Account
2009-04-12 11:13 am
www.tribute-audio.nl
Piano,

When we talk patents we think someone has come up with something original, not done before.
US patent system is a bit different; "patents" are often only used for commercial reasons, to prevent competitors from doing the same.
Audio Note's interstage transformer in their dac's is an example here in Europe.
When you investigate what it means most of the time the "patent" is valid in the US, or Europe, or just your own country. Patents which cover the whole world are the most expensive.

Pieter
 
Cut and paste out of a textbook. Nothing even clever about it. But since someone successfully re-patented the Darlington circuit with a tube in it, I guess the patent office doesn't expend much manpower on tube technology searches. Nice to have money to burn on such silly patents. This is probably just advertising-hype driven. If they don't have anything novel, they just fake it.
 
Oh, the patent has the cascode grids ultralineared? I couldn't see that in the tiny picture in post #1. At least it has something more than a plain vanilla cascode then. Still, UL'ing a cascode has been around for a while, as Bill just demonstrated.

Another issue is that 3 tubes stacked up is simply impractical and dangerous, considering the high B+ required, and all those floating filament supplies required. Putting some Mosfets up top sides would make the thing more practical, but nothing new though. I seem to recall Janneman posted a Fluke HV calibration amplifier that used that setup.
 
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Hi:
Click the link in the first post to get the patent and no the grids in the first implementation are not "ultra-lineared", the thing is just a straight ahead, diff cascode with active plate loads.
For something rather more interesting pull down this PDF http://www.pearl-hifi.com/06_Lit_Archive/01_Audio_Notes/Notes_on_a_Work_2.pdf and see page 24; some work a self-balancing diff stage that applied any common mode error to the "long tail" current source with the result that much higher and stable CMRR could be achieved over the life of the tubes.

Bill @ PEARL
 
I don't have the patent #. I recall someone else mentioned it once on the forum and I looked up the patent then, and sure enough it was. Might try searching the tube forum. Maybe try "tube patent" or "Darlington patent". The patent itself did not reference "Darlington" for obvious reasons, so searching the patent base for that won't work. It was more like "current assisted .... ".
 
For something rather more interesting pull down this PDF http://www.pearl-hifi.com/06_Lit_Archive/01_Audio_Notes/Notes_on_a_Work_2.pdf and see page 24; some work a self-balancing diff stage that applied any common mode error to the "long tail" current source with the result that much higher and stable CMRR could be achieved over the life of the tubes.

Just for the reference, a similar circuit (with solid state ccs) is discussed in this thread: http://www.diyaudio.com/forums/tubes-valves/160312-balance-ccs-long-tailed-pairs.html
 
"the number is 7482867"

Ah, now I can see it finally. Clearly the 1st diagram posted would not be patentable, but I see the patent goes on to elaborate with internal feedback pathes and UL'd cascodes. Maybe patentable. I'm sure one can find similar structures in the SS patents and literature. What is really odd here is why would they bother. It's impractical with the high B+ required and the many floating filaments, and then unsellable with "FEEDBACK" written all over it.

-----------------------

I did a little searching in the forum to try and find the Darlington patent reference. No luck so far, but sometimes one can trace back references in a later patent. This interesting patent did show up: 6229387 which references 6175271 and 5909145. 6229387 is concerned with current multiplication of a tube using SS mirrors. The Darlington would be of the same genre. All of these are likely to be from guitar amplifier efforts, trying to get tube sound on the cheap (no OT or big tubes). There was also a list of tube patents someone came up with on the forum once. Should be able to find that, then look at the references from them if the Darlington one is not in there yet.
 
Why isn't output taken from the bottom of the CCS ?

Oh and I believe something similar (but with resistive load if I'm not mistaken) was posted here about 1 year ago, again a differental pair of triode cascodes.

That would probably be me, as I did that very thing with the Le Renard design.

That thingy is simply a triode differential driving two SRPPs, with the input fed into the SRPP's cathodes, instead of grids. You'd be better off doing what I did: cascode LTP driving cathode followers to get the gain with a Lo-Z output.

That patent is just full of prior art, definitely won't stand up if challenged, and looks like a defensive patent.
 

tomchr

Member
Paid Member
2009-02-11 12:58 am
Calgary
www.neurochrome.com
When we talk patents we think someone has come up with something original, not done before.
US patent system is a bit different; "patents" are often only used for commercial reasons, to prevent competitors from doing the same.
Audio Note's interstage transformer in their dac's is an example here in Europe.
When you investigate what it means most of the time the "patent" is valid in the US, or Europe, or just your own country. Patents which cover the whole world are the most expensive.

The only reason to apply for a patent is to get a monopoly on using that particular invention. Reasons for getting such monopoly is that you can charge money to license the technology to others or prevent your competitors from gaining a competitive advantage over you by using the same circuit. I believe this is true regardless of where in the world the patent is applied for. Of course, there's also the satisfaction (ego boost) of having a patent on your resume (CV in the rest of the world).
The reason a monopoly is granted is that it's payment for sharing your inventions, hence advancing the field.

In the US, to get a patent the invention must be
1) Novel
2) Non-obvious
3) Possible to reproduce by someone skilled in the art

That's the US law anyway. In reality, it seems patents are granted without much review and often fail to show that they're non-obvious or even novel. That's when law suits are filed to try to get the patent invalidated.
Also note that there is no requirement that the invention actually works(!).

In the US corporate world - at least in the semiconductor industry - every company has a large stack of patents. It may be that one could show that company A infringes on company B's patent, but usually this does not result in a law suit as the opposite is likely to be true as well. At this point it becomes more of a "my stack is larger than your stack" game.

~Tom
 
My confusion likely on the Darlington patent:

I found an old post by myself about seeing a Sziklai tube/SS circuit (a PNP at the plate, versus the NPN at the cathode for the Darlington) patent. And then hoping that the Darlington was not patented too. So I must have confused the two versions. Sorry for the confusion.
 
My confusion likely on the Darlington patent:

I found an old post by myself about seeing a Sziklai tube/SS circuit (a PNP at the plate, versus the NPN at the cathode for the Darlington) patent. And then hoping that the Darlington was not patented too. So I must have confused the two versions. Sorry for the confusion.

Sounds weird. I use such "Sziklai" many years and even in worst nightmare could not expect it to be patented.

Let's patent "interconnection between conductors using melted metal" :D

We can make DIYAudio very rich such a way. ;)
 
How do you expect to melt that solder without my patent on the soldering gun for melting the new lead free solders? :D (no, no, I bought up all the old NOS leaded solder too)

Such current boost patents I think have to be guitar amp related. Trying to get tube sound (and distortions) on the cheap likely. Defensive. Rather unlikely anyone would try to use them in offensive manner, that would collapse their defense after a court ruling.
 
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