janneman said:
So the fellow who discovered fire should have discovered all of chemistry, including the composition of air and wood, the concept of oxidation, the idea that heating food made it more easily chewed and and digested? Er...no. Regardless of "proof" and "explanations" and "hypotheses" and "theories," you go where the effect leads you. To which you say, "But, Grey, lightning and fire are obvious!"
And so they are.
And so are some of the audio phenomena which people so blithely ignore because they aren't "proven" or because the explanations offered simply don't suit some peoples' preconceived world views.
Am I to take it that you've never read Picking Capacitors by Jung and Marsh? Never even heard of it? It was published in Audio magazine back in, I think, 1977. They used to have it online at www.capacitors.com. That was the article that saved the hides of people who had been claiming, based purely on their listening experiences, that all capacitors were not created equal for audio purposes. I'm still hoping that we'll see an equivalent article for resistors someday.
Grey
PMA said:
Popcorn noise is not specific to opamps, but to semiconductors in general. It was a serious issue 20 years ago, when I was in Scott's business 🙂 The origin and causes of the popcorn noise are today very well understood and it was proven that the cause was improper silicon processing (details available on request). Today, I don't think there is any integrated opamp available on the market that has popcorn noise as a concern for the end user.
I've got experience with TO-220 driver (2SC2238-2SA968) that makes crackling noise when they are hot. Is this "Popcorn noise", appears when the silicon is hot?
lumanauw said:
Popcorn noise is not directly related to device temperature, however it depends on (increases with) the bias current. If the heating is due to/associated with a significant increase in the bias current, then I would say it is possible. Only an amplitude distribution measurement would tell for sure, because the popcorn noise has a very typical bimodal (non-gaussian) distribution.
GRollins said:
Grey,
You really have a knack for picking the wrong analogies. Fire is obvious because you can see it, smell it. If you take a friend to show it, he sees it, smells it, burn your hand if you touch it. That's acceptable proof to most people I would think; it is for me.
The audio phenomena you mentioned are not proven to the same extend as the fire is proven. They are not proven at all. And when people do a serious effort to try to proof that, objectively, there are these 'phenomena', they find no evidence.
[snip]Am I to take it that you've never read Picking Capacitors by Jung and Marsh? Never even heard of it? It was published in Audio magazine back in, I think, 1977. They used to have it online at www.capacitors.com. [snip]Grey [/QUOTE]
Don't be silly. I read it before it was published.
Jan Didden
Lumanauw, what you are talking about is NOT popcorn noise. Popcorn noise is a low level noise problem originally associated with impurities such as gold atoms in the component. For others, who might want to have a deeper knowledge of 'popcorn noise' I recommend: 'Noise in Electronic Devices and Systems' M. J. Buckingham, p.187.
Yes, "popcorn" looks like slow (in Hz) sudden low level jump between 2 stable states, it can be observed in time domain, after amplification (of noise). And sounds like when you fry a popcorn.
There is still popcorn noise and GR (generation recombiation) noise in plenty of amplifiers these days. And not in plenty others. The literature on noise could fill several 18-wheelers but much of the good stuff is in papers not books. Since the designer can't do much about it after the fact reading it all is more on the academic side of thing. Especially things lke popcorn noise, just avoid it.
Design issues like optimum current densities are another thing, there are several books with useful advice, like the one John mentioned.
Design issues like optimum current densities are another thing, there are several books with useful advice, like the one John mentioned.
BTW the lack of 7th in those plots is probably a case of fortuitous cancellation rather than by design 🙂
john curl said:
Warm ups,
J. W. Haslett, E. J. M. Kendall, and F. J. Scholz, "Low frequeny noise mechanisms
in MOS structures," presented at the IEEE Int. Electron Devices Meet.,
Washington, D. C., Dec. 1972.
J. W. Haslett and E. J. M. Kendal, "Temperature dependence of low-frequency
noise in junction-gate FET's," <i>IEEE Trans. Electron Devices</i>, vol. ED-19, pp.
943-950. Aug. 1972.
J. W. Haslett and E. J. M. Kendall "The measurement of low frequency noise
from 30 to 300 K," <i>J. Phys. E.</i>, vol. 5, pp. 1149-1151, 1972.
Thanks Scott, but these papers are even older than Buckingham's book. However on pp. 198-200, there are a few other slightly newer references:
Conti M. and Corda G. (1974) 'Noise sources identification in integrated circuits through correlation analysis', IEEE J. Solid State Circuits SC-9, 124-133.
Roedel R. and Viswanathan C. R. (1975), 'Reduction of popcorn noise in integrated circuits'. IEEE Trans. Elect. Dev. , ED-10, 962-964.
There may be more, but I don't have them available.
Conti M. and Corda G. (1974) 'Noise sources identification in integrated circuits through correlation analysis', IEEE J. Solid State Circuits SC-9, 124-133.
Roedel R. and Viswanathan C. R. (1975), 'Reduction of popcorn noise in integrated circuits'. IEEE Trans. Elect. Dev. , ED-10, 962-964.
There may be more, but I don't have them available.
Older in this case is not need be less relevant, I think there has been some divergence over the years on understanding the sources of noise vs. simply eliminating them. Generation recombination noise can be analysed ad nauseum, but in the end, clean up your process.
Nothing up-to-date? My associates and I would really like to know if any jfet 1/f or burst noise theory has come to pass lately.
john curl said:
Really nothing much of note, there has been a little activity on MOSFET's. If it doesn't stop shipments on 24 bit A/D's it doesn't hit the bean counter's radar screen. R&D on this stuff costs serious money. Stock up or learn how to use op-amps 🙂 .
Actually, I have an associate who is making 'world class' instruments with paralleled 2SK389's working with 1000 second integration times. It is always a challenge to do better, but I might remind you that my total noise for the Levinson JC-1 pre-preamp (1973), the Sota Headamp (1980), or the Vendetta Research(1983) has always been 0.4nV/rt Hz or less than 1/2 the noise of the AD797. We are now reaching even further in the elimination of 1/f or burst noise through our own informal research, and I am also trying to help Linear Systems reduce the noise of their products as well through another individual who is a device designer.
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