Current Feedback Amplifiers, not only a semantic problem?

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#2,621
Jan and Hans,

I’ve been thinking about your posts of the last day or so.

My son likes to recount a comedy routine that he found particularly funny. A politician doesn’t let the fact that he won his race stop him from continuing to fund television campaign commercials and make stump speeches denigrating his erstwhile opponent. He even berates him in a loud voice when he meets him in a supermarket parking lot!

I’m doing nothing like this.

First of all, I clearly haven’t “won” anything. Secondly, I’m not instigating posts – I’m just responding to them. And why not? If people with whom I disagree (I’m not referring to you two) are willing to post arguments, there’s always a chance (I acknowledge it’s a slim one) that a response could influence their thinking.

I don’t understand those who post disparaging comments about the continuation of this discussion (again, not you.) It contributes nothing positive. If they dislike or have no interest in the ongoing conversation, they can ignore it. Better yet, just unsubscribe to the thread. It’s not as if much else is going on there, and after all, this very topic is the subject of the thread. Even if it weren’t, it’s not as if the opportunity to talk about something else is being lost.

So do me a favor and help me out here, gents. Don’t spare my feelings. Educate me. Just what is the nature of the objections to my ongoing posts?

Thanks in advance for your reply.
 
#2,622
CPaul said:
Jan and Hans,
[snip]
It contributes nothing positive.
[snip]
So do me a favor and help me out here, gents. Don’t spare my feelings. Educate me. Just what is the nature of the objections to my ongoing posts?
Click to expand...

I think many here (me included) understand that this discussion contributes nothing whatever because it only regurgitates past posts.

I have nothing against you or anybody else here, on the contrary, I enjoyed your recent articles in AX, for instance. I just can no longer take this discussion with any measure of seriousness.
And frankly, it is beyond me what you hope to take out of it. But its your life.

I do now and then bring on new viewpoints for those who have minds open enough and willing to grow in understanding of these circuits, like the Steffes stuff I posted.
So if I find something of interest tomorrow I'll do it again. There must be hundreds of lurkers out there that drop in once in a while to see if there are any morsels worthwhile to pick up 🙂

Jan
 
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#2,623
Thanks much for your reply.

jan.didden said:
I think many here (me included) understand that this discussion contributes nothing whatever because it only regurgitates past posts.
Click to expand...

I agree that regurgitation would be useless. I do not (consciously at least) regurgitate.

jan.didden said:
...

I do now and then bring on new viewpoints for those who have minds open enough and willing to grow in understanding of these circuits, like the Steffes stuff I posted.
Click to expand...

That's definitely worthwhile. And that's exactly what I am trying to do and believe that I am doing - challenging others to look at this matter in yet one more new and different way.

Thanks again for your response.
 
#2,624
On quiet reflection, I must admit that I have been wrong all along. I finally decided to purchase several CFA samples, and try them out in my personal laboratory, in what proved to be a vain effort to corroborate my theses. My conclusions:

1. I found that the signal being fed back to the inverting input is indeed mostly current, with voltage playing only an almost irrelevant role,
so the designation "current feedback" is really appropriate. Please, no more "so-called current-feedback". Just plain "current feedback" will do.

2. I have repeatedly stated that the input stage "must not" be treated as a unity-gain voltage buffer with vanishingly small output resistance.
But then, in Figure A4, I modeled the output buffer, which at the transistor level is "identical" to the input buffer, as a unity-gain buffer with zero
output resistance! What a contradiction!

3. The so-called "gain node" should be left untouched. My fatal error was to load it down with a 4.5 kilo-Ohm resistor, which totally invalidates
the very raison d'etre of the CFA. So all my simulation efforts to prove the absurd can be deemed as a futile exercise to turn energy into solid waste...

I ought to apologize to the various individuals that I have treated unfairly, or even tried to offend, but I feel too humble and too small to find the courage to do it.

What a fool I have been!

Kind regards,

You know who I am.
 
#2,626
syn08 said:
Sorry, then I must have missed the whole purpose of your reply/comment/expanse. I'm having a hard time tying COD on two concepts ("expansive" and "compressive") that don't make any sense to me in this context, probably a 'bout of ADD on my side.
Click to expand...
That’s hardly an example of me claiming magical properties for CFA’s is it? Reread it.

About the whole history of CFA and the notion of current feedback, Comlinear were the first of the semi companies to present it in its currrnt IC form, but I don’t disagree what we call current feedback was being employed before that. We thrashed this subject to death and Acott Wurcer also weighed in correcting a few of mine and others misconceptions.

Anyway, good luck with finding any posts by me claiming CFA’s are superior in every way to VFA or that they possess magical properties.
🙂
 
#2,628
youknowwhoiam said:
On quiet reflection, I must admit that I have been wrong all along. I finally decided to purchase several CFA samples, and try them out in my personal laboratory, in what proved to be a vain effort to corroborate my theses. My conclusions:

1. I found that the signal being fed back to the inverting input is indeed mostly current, with voltage playing only an almost irrelevant role,
so the designation "current feedback" is really appropriate. Please, no more "so-called current-feedback". Just plain "current feedback" will do.

2. I have repeatedly stated that the input stage "must not" be treated as a unity-gain voltage buffer with vanishingly small output resistance.
But then, in Figure A4, I modeled the output buffer, which at the transistor level is "identical" to the input buffer, as a unity-gain buffer with zero
output resistance! What a contradiction!

3. The so-called "gain node" should be left untouched. My fatal error was to load it down with a 4.5 kilo-Ohm resistor, which totally invalidates
the very raison d'etre of the CFA. So all my simulation efforts to prove the absurd can be deemed as a futile exercise to turn energy into solid waste...

I ought to apologize to the various individuals that I have treated unfairly, or even tried to offend, but I feel too humble and too small to find the courage to do it.

What a fool I have been!

Kind regards,

You know who I am.
Click to expand...
I discovered that this person is called Soufiane Bendaoud. He's obviously a fraud who doesn't know what he is talking about.
 
#2,635
CPaul said:
I don’t understand those who post disparaging comments about the continuation of this discussion [..] It contributes nothing positive. If they dislike or have no interest in the ongoing conversation, they can ignore it. Better yet, just unsubscribe to the thread. [...] after all, this very topic is the subject of the thread. Even if it weren’t, it’s not as if the opportunity to talk about something else is being lost.
Click to expand...
Jan
 
#2,636
By the way... where is CPaul? In the aforementioned discussion it was Chris who came up with a mechanism to test black box devices in order to determine if a device can be characterized as a VFA or CFA. Most of his detractors had to see inside the boxes before making their determinations, as otherwise he was unopposed. From my understanding Chris was a brilliant guy.
 
#2,639
Time to resurrect this thread ?

Coincidence I started a thread about feedback
at the beginning of last october in France
(sorry I't is infrench but there quite a lot of drawings made with Tina simulator)
https://forums.melaudia.net/showthread.php?tid=12164 (25 pages;249 posts)
https://forums.melaudia.net/showthread.php?tid=12266 (only tow posts)

First, I started by exposing what is the real Ohm's law and
how the current across a bipolar transistor is controlled.
(there were hostile reactions).

Then I began to explain how feedback works
using a simple way I did not see elsewhere.
My method is based on examples. I hope I will import it here.
 
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