mikeks said:
Yes, so what? I read that years ago and knew already before that the ideal op amp model is not a perfect model of real op amps. Gilbert is just warning stupid people from thinking that that is the case. Did you think it modelled real op amps before reading Gilbert?
If you don't understand the use and puropse of theoretical ideal models, fine, don't bother. Just don't assume that they are useless just because you don't understand them. It is strange that someone who frequently links to scientific papers seems to have such difficulties to understand theory that even the theory used by such pragmatic people as application engineers is beyond him. Do you really really think that TI, AD and others would waste a lot of money on doing the necessary research and other efforts to write these application notes if they didn't think they served a purpose to help other engineers to solve real problems? Since they are not academics they might perhaps sometimes do some formal errors that would never be accepted in scientific papers, but those are usually irrelevant from the application point of view.
Besides, it is not my model. It is the standard op amp model that you will find in practically every textbook on EE. Those books that are intended as more than an introductory text will usually refine the model and discuss how real op amps behave. But I thought you had read such books?
Christer said:
I am sorry, Christer, you insisted that this model was valid. Otherwise why did you insist on beating everbody about the head with it?
As a matter of fact, I knew it didn't model real op amps before you left your diapers.
Christer said:
😀
Christer said:
Such books can be safely deposited at the nearest paper recycling plant without causing undue intellectual loss.
They are egregiously misleading, and do untold harm to the education and comprehension of hundreds of students.
You are, clearly, an excellent example of this problem.
mikeks, personal attacks are not allowed as you well know.
mikeks said:
Don't be stupid. I am sure nobody has yet come up with a perfect mathematical description of any real op amp. They are much too complex for that. You will always have to work with an approximation of it. Since it would be intractable to always use the best model we know of, we often use simplified models. The level of simplification must be choosen depending on the use. It is usually simpler to start with a theoretically perfect model and add those paramerters that cannot be approximated with the ideal values than to start with the most perfect model we know of and try to simplify it. The validity of the model must of course be judged depending on how you intend to use it. And since you still seem not to read what I write, I have already said before that the perfect models of VFB and CFB op ams do not correspond to any real op amps, but are extreme cases of approximation. They are useful for understanding the fundamentals of how they work and often, with some additional parameters, sufficient for designing with them.
Everybody is entitled to use the model they find useful for their purpose, but you seem not to allow that. Only the models that you approve of are to be accepted. Please try telling TI and AD to stop using their wrong models. At least we here on the forum know how incredibly wrong we all are since you have enlightened us, but think of all the poor engineers out there who don't read this forum, and still believes in app notes that have not been approved by you.
This is not about any particular model being right or wrong. A model is a model. Nothing more, nothing less. I have never tried to claim that your model of current feedback is wrong. That would be a stupid claim. I have claimed though that there are models that are more ideal and abstract, and do not make assumptions about a particular implementation. Neither model is more right or wrong than any other. They are different models, and it is up to the person using a model to decide if it is useful for the particular purpose.
You seem to seek a universal truth where there is no such thing.
mikeks said:
Do you realize that you are contradicting yourself here?
Either I am stupid and believe the simplified model is always OK, but would I then point out that there are better books that go deeper into the topic? Or you could mean that even those books which do model op amps in a better way should be recycled, but that seems an unlikely interpretation judging from what you haver written previously.
Sorry SY, and Mikeks. It wasn't meant as a personal attack. Probably a subtle difference between langugages here.
Since Mikeks was just sinbinned, it would be unfair of me to make any further comments on his postings. And I am anyway confident that the average reader is clever enough to check up the context of quotations used in postings.
It seems he will never understand me and I will never understand him. I don't think there would be any point for either of us to continue the discussion, so this seems the moment to just give up and accept that we simply don't understand each othe and probably never will, which I regret I didn't accept much earlier.
It seems he will never understand me and I will never understand him. I don't think there would be any point for either of us to continue the discussion, so this seems the moment to just give up and accept that we simply don't understand each othe and probably never will, which I regret I didn't accept much earlier.
I think the "moment to just give up" was back at page 4. 
This is not an argument. It is just a series of pointless contradictions!
No it isn't.
This is not an argument. It is just a series of pointless contradictions!
No it isn't.
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