Cursitor Doom wrote...> > Jim Thompson wrote: > >> AKA Flicker Noise > > Yup, pink noise. No jittering/jitterbugging involved. ;)Actually, I'd say you're wrong. The zener noise that we see in avalanche mode (greater then 7 volts or so) is due to step-wise "microplasma" ns-scale changes in current. A decade or so ago we fully discussed it here on s.e.d., complete with measurements, waveforms, detailed physics paper references and the works. Nailed it down. As it happens, the jitterbug analogy isn't so far off. This avalanche jitterbug noise source is not available in the low-voltage field emission zener operating mode, so using two sub-6-volt zeners in series in place of a higher-voltage zener, or any of many other good schemes would indeed be a good idea. -- Thanks, - Win
Combating Zener Jitter
Started by ●May 21, 2017
Reply by ●May 21, 20172017-05-21
Reply by ●May 22, 20172017-05-22
On Sun, 21 May 2017 17:10:33 -0700, Winfield Hill wrote:> This avalanche jitterbug noise source is not available in the > low-voltage field emission zener operating mode, so using two > sub-6-volt zeners in series in place of a higher-voltage zener, or any > of many other good schemes would indeed be a good idea.Well, I can't argue with *you* of all people! So we have a new term for it, then. It's not flicker noise, it's not pink noise, it's "jitterbug noise" to coin a phrase. Thanks, Win!
Reply by ●May 22, 20172017-05-22
On Sunday, May 21, 2017 at 8:10:45 PM UTC-4, Winfield Hill wrote:> Cursitor Doom wrote... > > > > Jim Thompson wrote: > > > >> AKA Flicker Noise > > > > Yup, pink noise. No jittering/jitterbugging involved. ;) > > Actually, I'd say you're wrong. The zener noise that we > see in avalanche mode (greater then 7 volts or so) is due > to step-wise "microplasma" ns-scale changes in current. > A decade or so ago we fully discussed it here on s.e.d., > complete with measurements, waveforms, detailed physics > paper references and the works. Nailed it down. As it > happens, the jitterbug analogy isn't so far off.Those are some nice threads, I went back and read them a few years ago. Turning lemons into lemonade, a 20V zener baised at ~10uA makes a nice noise source out to ~100's of kHz. I've also been reading Hamamatsu app notes on their Silicon PMT. Which is really a Si avalanche photodiode in "Geiger-mode" (biased above the breakdown voltage.) Fun stuff. George H.> > This avalanche jitterbug noise source is not available > in the low-voltage field emission zener operating mode, > so using two sub-6-volt zeners in series in place of a > higher-voltage zener, or any of many other good schemes > would indeed be a good idea. > > > -- > Thanks, > - Win
Reply by ●May 22, 20172017-05-22
George Herold wrote:> I've also been reading Hamamatsu app notes on their Silicon PMT. > Which is really a Si avalanche photodiode in "Geiger-mode" > (biased above the breakdown voltage.) Fun stuff. >We've been experimenting with Silicon photomultipliers at work, and while they have a number of issues, they certainly have huge advantages over vacuum photomultipliers. We've been using the SensL product. The biggest issue is the breakdown voltage is temperature sensitive, and gain varies WIDELY with small changes in temperature or bias voltage. Jon
Reply by ●May 22, 20172017-05-22
On Monday, May 22, 2017 at 1:02:20 PM UTC-4, Jon Elson wrote:> George Herold wrote: > > > > I've also been reading Hamamatsu app notes on their Silicon PMT. > > Which is really a Si avalanche photodiode in "Geiger-mode" > > (biased above the breakdown voltage.) Fun stuff. > > > We've been experimenting with Silicon photomultipliers at work, and while > they have a number of issues, they certainly have huge advantages over > vacuum photomultipliers. We've been using the SensL product. > > The biggest issue is the breakdown voltage is temperature sensitive, and > gain varies WIDELY with small changes in temperature or bias voltage.Huh, I didn't know about Sens-L. Thanks! Hey they make one that is sensitive in the NIR! http://sensl.com/products/r-series/ I can afford $78 too... if they were in stock. (Oh I guess not released yet. I had to register to look at the data sheets.... R-series has ~25% PDE at 800 nm.) I wonder if they have to make them thin, which is why the are not so good in the NIR? Do you notice any problem with after pulsing? It's sorta like dark count, but a different noise source. George H.> > Jon
Reply by ●May 22, 20172017-05-22
George Herold wrote:> > Huh, I didn't know about Sens-L. Thanks! Hey they make one that is > sensitive in the NIR! > http://sensl.com/products/r-series/ > I can afford $78 too... if they were in stock. > (Oh I guess not released yet. I had to register to look at the data > sheets.... R-series has ~25% PDE at 800 nm.) I wonder if they have > to make them thin, which is why the are not so good in the NIR? > > Do you notice any problem with after pulsing? It's sorta like dark count, > but a different noise source.We haven't really seen after pulsing in our (very limited so far) testing. As long as you don't turn the bias up too high, the dark current pulses are well below the type of signals we are using, so they just about drop out of the system. That's way better than our results with vacuum PMTs, where the dark current is typically enough that it triggers our discriminators. SensL also has SiPMs that bring out a fast output that is capacitively coupled from each micropixel. You get really good time response from that. Each micropixel has about an 18 K Ohm quench resistor in series for the "slow" output, which we thought would give a horrible time response. But, as we typically fire hundreds of micropixels at a time, it actually is nowhere that bad. Yeah, they have stupid rules about registering to read advertising copy, I have NO IDEA why outfits do this. SiPMs are not exactly the newest concept out there. Jon
Reply by ●May 22, 20172017-05-22
On 05/22/2017 10:33 AM, George Herold wrote:> On Sunday, May 21, 2017 at 8:10:45 PM UTC-4, Winfield Hill wrote: >> Cursitor Doom wrote... >>> >>> Jim Thompson wrote: >>> >>>> AKA Flicker Noise >>> >>> Yup, pink noise. No jittering/jitterbugging involved. ;) >> >> Actually, I'd say you're wrong. The zener noise that we >> see in avalanche mode (greater then 7 volts or so) is due >> to step-wise "microplasma" ns-scale changes in current. >> A decade or so ago we fully discussed it here on s.e.d., >> complete with measurements, waveforms, detailed physics >> paper references and the works. Nailed it down. As it >> happens, the jitterbug analogy isn't so far off. > > Those are some nice threads, I went back and read them a few years > ago. Turning lemons into lemonade, a 20V zener baised at ~10uA > makes a nice noise source out to ~100's of kHz. > > I've also been reading Hamamatsu app notes on their Silicon PMT. > Which is really a Si avalanche photodiode in "Geiger-mode" > (biased above the breakdown voltage.) Fun stuff. > > George H.I'm in conversation with a big biosci company about cost-reducing their detection subsystems, so this has come up a lot lately. "Si PMTs" are basically an array of APDs wired in parallel and run in Geiger mode. The idea is that having multiple pixels allows you to extend Geiger mode to pulses containing more photons without losing resolution. AFAIK the biggest ones are about 120x120 pixels. Trouble is, even when uniformly illuminated they start to become nonlinear at depressingly low photon numbers--the linearity error is 10% once 10% of the pixels have fired, because only 90% are available. You can apply a correction for this that might work adequately up to about 25%, but it starts to run out of gas pretty fast compared with a real PMT. Their dynamic range requirements were much too large for this to work for them. Also the dark counts are ridiculously worse--more than 10**6 times worse on an area basis. The real advantage of MPPCs is that you can do thresholding, which helps reject single-pixel events at the expense of sensitivity. That reduces the effective dark count rate by a lot. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●May 22, 20172017-05-22
On Mon, 22 May 2017 15:12:20 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 05/22/2017 10:33 AM, George Herold wrote: >> On Sunday, May 21, 2017 at 8:10:45 PM UTC-4, Winfield Hill wrote: >>> Cursitor Doom wrote... >>>> >>>> Jim Thompson wrote: >>>> >>>>> AKA Flicker Noise >>>> >>>> Yup, pink noise. No jittering/jitterbugging involved. ;) >>> >>> Actually, I'd say you're wrong. The zener noise that we >>> see in avalanche mode (greater then 7 volts or so) is due >>> to step-wise "microplasma" ns-scale changes in current. >>> A decade or so ago we fully discussed it here on s.e.d., >>> complete with measurements, waveforms, detailed physics >>> paper references and the works. Nailed it down. As it >>> happens, the jitterbug analogy isn't so far off. >> >> Those are some nice threads, I went back and read them a few years >> ago. Turning lemons into lemonade, a 20V zener baised at ~10uA >> makes a nice noise source out to ~100's of kHz. >> >> I've also been reading Hamamatsu app notes on their Silicon PMT. >> Which is really a Si avalanche photodiode in "Geiger-mode" >> (biased above the breakdown voltage.) Fun stuff. >> >> George H. > >I'm in conversation with a big biosci company about cost-reducing their >detection subsystems, so this has come up a lot lately. "Si PMTs" are >basically an array of APDs wired in parallel and run in Geiger mode. >The idea is that having multiple pixels allows you to extend Geiger mode >to pulses containing more photons without losing resolution. > >AFAIK the biggest ones are about 120x120 pixels. Trouble is, even when >uniformly illuminated they start to become nonlinear at depressingly low >photon numbers--the linearity error is 10% once 10% of the pixels have >fired, because only 90% are available. > >You can apply a correction for this that might work adequately up to >about 25%, but it starts to run out of gas pretty fast compared with a >real PMT. Their dynamic range requirements were much too large for this >to work for them. > >Also the dark counts are ridiculously worse--more than 10**6 times worse >on an area basis. > >The real advantage of MPPCs is that you can do thresholding, which helps >reject single-pixel events at the expense of sensitivity. That reduces >the effective dark count rate by a lot. > >Cheers > >Phil HobbsIf your customer is gigantic enough, maybe Hamamatsu would sell them the cute little MEMS PMTs. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●May 22, 20172017-05-22
On 05/22/2017 03:48 PM, John Larkin wrote:> On Mon, 22 May 2017 15:12:20 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 05/22/2017 10:33 AM, George Herold wrote: >>> On Sunday, May 21, 2017 at 8:10:45 PM UTC-4, Winfield Hill wrote: >>>> Cursitor Doom wrote... >>>>> >>>>> Jim Thompson wrote: >>>>> >>>>>> AKA Flicker Noise >>>>> >>>>> Yup, pink noise. No jittering/jitterbugging involved. ;) >>>> >>>> Actually, I'd say you're wrong. The zener noise that we >>>> see in avalanche mode (greater then 7 volts or so) is due >>>> to step-wise "microplasma" ns-scale changes in current. >>>> A decade or so ago we fully discussed it here on s.e.d., >>>> complete with measurements, waveforms, detailed physics >>>> paper references and the works. Nailed it down. As it >>>> happens, the jitterbug analogy isn't so far off. >>> >>> Those are some nice threads, I went back and read them a few years >>> ago. Turning lemons into lemonade, a 20V zener baised at ~10uA >>> makes a nice noise source out to ~100's of kHz. >>> >>> I've also been reading Hamamatsu app notes on their Silicon PMT. >>> Which is really a Si avalanche photodiode in "Geiger-mode" >>> (biased above the breakdown voltage.) Fun stuff. >>> >>> George H. >> >> I'm in conversation with a big biosci company about cost-reducing their >> detection subsystems, so this has come up a lot lately. "Si PMTs" are >> basically an array of APDs wired in parallel and run in Geiger mode. >> The idea is that having multiple pixels allows you to extend Geiger mode >> to pulses containing more photons without losing resolution. >> >> AFAIK the biggest ones are about 120x120 pixels. Trouble is, even when >> uniformly illuminated they start to become nonlinear at depressingly low >> photon numbers--the linearity error is 10% once 10% of the pixels have >> fired, because only 90% are available. >> >> You can apply a correction for this that might work adequately up to >> about 25%, but it starts to run out of gas pretty fast compared with a >> real PMT. Their dynamic range requirements were much too large for this >> to work for them. >> >> Also the dark counts are ridiculously worse--more than 10**6 times worse >> on an area basis. >> >> The real advantage of MPPCs is that you can do thresholding, which helps >> reject single-pixel events at the expense of sensitivity. That reduces >> the effective dark count rate by a lot. >> >> Cheers >> >> Phil Hobbs > > If your customer is gigantic enough, maybe Hamamatsu would sell them > the cute little MEMS PMTs.Wouldn't that be nice! Of course the designer has probably died of old age by now.... Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●May 22, 20172017-05-22
On Monday, May 22, 2017 at 2:46:27 PM UTC-4, Jon Elson wrote:> George Herold wrote: > > > > > > Huh, I didn't know about Sens-L. Thanks! Hey they make one that is > > sensitive in the NIR! > > http://sensl.com/products/r-series/ > > I can afford $78 too... if they were in stock. > > (Oh I guess not released yet. I had to register to look at the data > > sheets.... R-series has ~25% PDE at 800 nm.) I wonder if they have > > to make them thin, which is why the are not so good in the NIR? > > > > Do you notice any problem with after pulsing? It's sorta like dark count, > > but a different noise source. > We haven't really seen after pulsing in our (very limited so far) testing. > As long as you don't turn the bias up too high, the dark current pulses are > well below the type of signals we are using, so they just about drop out of > the system. That's way better than our results with vacuum PMTs, where the > dark current is typically enough that it triggers our discriminators.Huh, that's strange. I thought these Si-pmt's had more dark count. If you keep the bias low enough it may just be an avalanche PD, and not one in geiger mode. (?) I recall a SPAD paper that said the dark count goes as the square the the excess voltage (IIRC), where excess voltage is voltage above the threshold for geiger mode.> > SensL also has SiPMs that bring out a fast output that is capacitively > coupled from each micropixel. You get really good time response from that. > Each micropixel has about an 18 K Ohm quench resistor in series for the > "slow" output, which we thought would give a horrible time response. But, > as we typically fire hundreds of micropixels at a time, it actually is > nowhere that bad. > > Yeah, they have stupid rules about registering to read advertising copy, I > have NO IDEA why outfits do this. SiPMs are not exactly the newest concept > out there.No worries, I was interested enough to register. (What's one more piece of spam in my inbox...) George H.> > Jon
