During
08, r/NoiseVsDC.pdf
The noise is always at least 1.76dB above shot noise..even at high currents? That's different. (At least in my limited experience.) You've made a feedback 'element' that has less thermal noise than a resistor... but at the expense of added shot noise?
George H.
I haven't been seeing a "doughnut hole" in resistor value distributions lately. I think that old carbon comps and such had a lot of variation, so the parts were binned after manufacturing for accuracy. Laser trimming doesn't work that way.
It is hard to find high-accuracy resistors up in the megohms. Maybe the metal films are getting too thin to be stable.
John
it
=A0!!!
Why are you raging, Phil?
Unnecessary comma.
John
truly:
Yes. "Photon coupled" means a current-feedback architecture where the feedback is also a photocurrent--but in any previous method of that sort, the feedback photocurrent has full shot noise, whereas this one has only half of the shot noise. (I think that's a pretty neat parlor trick at 10 nA--it would be easy at higher current.)
The circuit idea was provoked by a (quite different) one that I did for Samsung's development folks in 2009. Their problem was doing long-range IR communication in the presence of electronic-ballast fluorescent lights, which put out tons of stuff to beyond 1 MHz. That one met spec quite handily, and they seemed very pleased.
I wasn't satisfied with the way it fell apart down in the low nanoamps, though. It was an AC-coupled design with low frequency current feedback to stabilize the operating point. I was deriving the low-frequency DC feedback current from a BFT25A, degenerated by three diode-connected BFT25As in its emitter. Diode degeneration reduces the shot noise contribution of the transistor by 6 dB, which helps a lot.
The transistors just didn't have high enough f_T at those current levels--as I sometimes tend to forget, a diode-connected transistor is actually the world's simplest feedback amplifier!
So since it bothered me so much, I started looking around for a way to improve the noise vs bandwidth tradeoff down in the nanoamps, and preserve DC coupling. There turned out to be this insanely cute method... and the PH200 is the first result. I haven't decided whether to patent it or not--I may get motivated to file a provisional and then do a real patent if it sells well. Either way, I'll probably do an Optics & Photonics News article on it--the idea is pretty widely applicable, and anyway, they generate lots of consulting inquiries.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 email: hobbs (atsign) electrooptical (period) net http://electrooptical.net
,
mp
ink
200/NoiseVsDC.pdf t e kI'm looking forward to the article. Cute methods should be shared.
George H.
t- Hide quoted text -
truly:
-- Good on you; do well!
I went through about half of his "Black Magic" book, highlighting the truly ludicrous parts. Then the highlighter pen died.
John
Where's the donut hole?
John
Thanks, John.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 email: hobbs (atsign) electrooptical (period) net http://electrooptical.net
"John Larkin"
** The Brat ????** Opinion, not fact.
Only a few percent of folk suffer psychoses at any time in their lives.
In any case, psychologists are the wrong people to ask.
.... Phil
Suicide?
-- You can't fix stupid. You can't even put a band-aid on it, because it's Teflon coated.
Oh, the chapter on Fluorescent Yellow Magic?
John
It's higher than that, or Obama would have never been elected. :(
-- You can't fix stupid. You can't even put a band-aid on it, because it's Teflon coated.
That's what you tell your inflatable sheep?
-- You can't fix stupid. You can't even put a band-aid on it, because it's Teflon coated.
I'm starting to think that O is a bit weird himself. I don't think he likes being President, either.
John
Of course he's weird. Who in their right mind would want to be President?
It's a thankless job. Most of the work is in orchestrating compromises that Congress is willing to go along with, and nobody values that - he's always going to be betraying someone's principles.
It's like electronic engineering, where most of the work is in finding the right connectors, and all the fuss is about innovative circuit design.
-- Bill Sloman, Nijmegen
It's easy to sit on the sidelines and throw stones (think Slowman) but work is hard. O loved running, but like a dog chasing a car, hadn't even thought about what to do with the car once he caught it.
How many psychologists does it take before you're full?
sorry ... leaving now ;-)
-- Rich Webb Norfolk, VA
On Jan 8, 11:09 am, John Larkin
Perhaps in the general population. They concentrate on internet in general and usenet in specific.
Half of usenet posters have Aspergers. A big percentage of the other half have other brain/psychology disorders like schizophrenia.
On usenet the percentage of posters without a brain/psych disorder is
25% if we're lucky.Others have noticed that internet users under 30 tend to use social networking sites and not usenet.
Archie is particularly interesting because he blatantly has a brain/psych disorder yet he denies it, apparently because he maintains an undeserved large ego. Archie is severely flawed yet hypercritical of others to the point of raging. It's a kind of "small man complex".
Archie's rages and threats combined with his various references to firearms might bear some investigation from Homeland Security, however.
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