X/SuperSymmetry - Am I Missing Something?

[CheffDeGaar]

Here's a fun thing to try

In the patent, it's the cross-coupling resistor that's the key, central thing. On the schematic on the patent cover page, it's resistor 40.

(While we're at it, let's also note that resistors 42 and 43 are connected to ground.)

Connect the middle of the cross-coupling resistor (resistor 40 in the patent cover page schematic) to ground. (Easily done when that resistor consists of two, equal resistors in series.)

Well, I'm quite a dumb head, but let me try...

Split the '40 resistor into two equal resistors. Assuming a perfect symmetry between the two halves of the circuit, the nodal point of the '40 resistors is indeed a virtual ground at DC. But if you connect it to real ground, you no longer have a diff pair, just two common source/emitter amps. The connection between the sources/emitters is mandatory to obtain the differential behaviour, whatever SuSy or not. It's this nodal point that "calculates" the difference between the (+) and (-) input signals and reflects it at the drains/collectors though the common gate/base behaviour of each half for each other. The '40 resistor is just a matter of gain. Just replace the '40 resistors by a wire, and add two degeneration resistors in the sources/emitters, replace the two current sources '26 and '27 by only one connected to the nodal point of the degeneration resistors, and you've got the same AC effect, and still SuSy.

Now remove resistors '22/'36, and '23/'37, and get rid of SuSy...

But I surely miss something

 

[Nixie]

Sorry to bruing up an old thread but I decided to take another look and try to understand SuSy again.

In my, possibly wrong, understanding, the major idea is that the amplifier amplifies a balanced signal and the feedback signals are fed to the other half of the amplifier instead of being fed back to the input of the same half, as is usually done.

Er... looking at the first figure on the patent, feedback goes back to the same side, not the opposite one (though in other examples such as the Aleph-X the NFB does go across). So this can't be it.

Well, after reading this thread I'm even more confused about the idea. So would any differential amplifier that had as input an LTP and feedback from both sides fall under the patent?

 

[flg]

This thread, as put by Grey I beleive, is most unfortunate... Dare I say, not worth reading... I sensed emotions and things from some participants that just did not need to be... Having expressed that... It's not the old thread you should be concerned with, just this one... Sometimes I get a little irritating, unententionally of coarse. If I am provoking anything other than interesting ideas, it's usually humor... Enough of that...
Basically speaking. on the first patent image the crosscoupling happens through the gate to source, through the coupleing R and through the other source to gate. Yes the X amps do it a little different but they both give F.B. to the opposite side. The X amps actually create positive feedback but to the opposite side it is negative... Any differences at the F.B. node are attemted to be corrected. So each F.B. node is correcting the other amps distortions. Looking at the differntial output, the distortions cancel... I hope I said something good there
You might try ZEN Ver 6 & 7 I beleive... N.P. probably wrote that following this thread??? They do a pretty good explaination, including pictures. They say pictures are worth a thousand words

 

[Nixie]

If my understanding is correct, then this amplifier violates the patent. I simulated it, injecting a pulse of voltage to represent distiortion on one output; it appears in phase on the other side, i.e. the effect that the patent seems to cover. Sure, the connection of the feedback from each side is at a strange place, but I don't see how that matters. Since this amp is being sold commercially (at headamp.com), isn't this a case of patent violation? Or am I missing something?

 

[flg]

IMHO, it looks like you might be right. That's current feedback I believe. I need to read the description. It is confusing

 

[darkfenriz]

If my understanding is correct, then this amplifier violates the patent. I simulated it, injecting a pulse of voltage to represent distiortion on one output; it appears in phase on the other side, i.e. the effect that the patent seems to cover. Sure, the connection of the feedback from each side is at a strange place, but I don't see how that matters. Since this amp is being sold commercially (at headamp.com), isn't this a case of patent violation? Or am I missing something?

Nixie, I once found even better example of such a technique, older than Nelson's patent but similar in some aspects.
I asked Nelson about this and his wise answer was something like 'the devil is in details'.
I think his patent is more about an implementation than invention, more like preserving circuit from being copied in commercial purposes.
That's business rather than science.
I bet Nelson don't mind if one used balanced feedback, same as no one should mind Nelson patenting a balanced feedback circuit.

regards

 

[Nelson Pass]

I simulated it, injecting a pulse of voltage to represent distiortion on one output; it appears in phase on the other side, i.e. the effect that the patent seems to cover.

When I look at it, I see that you get some cancellation, but it
should be partial, insofar as much of the cross-coupled error
signal is re-absorbed by the Source pin of input device on the
distortion-originating side.

 

[Nixie]

Doesn't seem to be such small a part at least in the simulator. If I shift the DC offset so that say the bottom of the output sine wave clips, the other side pretty much makes up for it, so that the differential output still looks like a sine.