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lock-in amplifier

Started by scot March 5, 2013
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
> On 3/9/2013 7:18 PM, Jim Thompson wrote: >> On Sat, 09 Mar 2013 18:39:30 -0500, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> On 3/9/2013 5:43 PM, John Larkin wrote: >>>> On Sat, 09 Mar 2013 15:05:26 -0700, Jim Thompson >>>> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>> >>>>> On Sat, 09 Mar 2013 16:54:19 -0500, Phil Hobbs >>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>> >>>>>> On 3/9/2013 4:35 PM, Jim Thompson wrote: >>>>>>> On Sat, 09 Mar 2013 16:29:09 -0500, Phil Hobbs >>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>>> >>>>>>>> On 3/9/2013 4:18 PM, Jim Thompson wrote: >>>>>>>>> On Sat, 09 Mar 2013 21:12:25 +0000, John Devereux >>>>>>>>> <john@devereux.me.uk> wrote: >>>>>>>>> >>>>>>>>>> Marte Schwarz <marte.schwarz@gmx.de> writes: >>>>>>>>>> >>>>>>>>>>> Hi John, >>>>>>>>>>> >>>>>>>>>>>>> Just think a little before flaming someone else, please. >>>>>>>>>>>> >>>>>>>>>>>> Flaming? Really? First time I've been accused of that! >>>>>>>>>>> >>>>>>>>>>> Well? You know how reliable Larkin's advice is >:-} >>>>>>>>>> >>>>>>>>>>>> It was an honest question. Just thinking aloud. >>>>>>>>>>> >>>>>>>>>>> What a question? >>>>>>>>>> >>>>>>>>>> Well you snipped it didn't you? >>>>>>>>>> >>>>>>>>>>>>> opto-fets can never have a charge injection, because the charge they >>>>>>>>>>>>> use to load the gate comes from the chanel that the charge flows >>>>>>>>>>>>> in. so the sum will allways be zero. I would say, this is as obvious >>>>>>>>>>>>> as Kirchhoffs law can be. >>>>>>>>>>>> >>>>>>>>>>>> Well, I don't think it is that obvious. >>>>>>>>>>> >>>>>>>>>>> Where do you expect the injected charge comming from? >>>>>>>>>> >>>>>>>>>> The voltage at the gate changes, relative to the other terminals. There >>>>>>>>>> is a capacitance between the gate and the other terminals. dQ=C.dV. >>>>>>>>>> >>>>>>>>>>>> Even Jim "charge is always conserved" Thompson doesn't seem to think so >>>>>>>>>>>> :) >>>>>>>>>>> >>>>>>>>>>> May be Jim woul tell his statement, too. >>>>>>>>>>> >>>>>>>>>>> I don't see any source for charge-injection. >>>>>>>>>> >>>>>>>>>> The photodiode? (or whatever equivalent generates the change in gate >>>>>>>>>> voltage). >>>>>>>>> >>>>>>>>> There is no gate in an opto-FET. Just a channel created by photon >>>>>>>>> impacts... and maybe that's the secret sauce... CONTINUOUS photon >>>>>>>>> impact is required to keep the FET on?? >>>>>>>>> >>>>>>>>> The pragmatist in me says, if opto-FET's were so wonderful, why am I >>>>>>>>> not seeing them implemented as marvelous analog switches that are >>>>>>>>> sweeping the world with their stupendous performance ?:-) >>>>>>>>> >>>>>>>>> ...Jim Thompson >>>>>>>>> >>>>>>>> >>>>>>>> Because they're 100 times too slow for general use, maybe. >>>>>>>> >>>>>>>> Cheers >>>>>>>> >>>>>>>> Phil Hobbs >>>>>>> >>>>>>> Maybe that's the answer... got to pile on a stream of photons before >>>>>>> anything happens. Or too high an ON resistance? >>>>>>> >>>>>>> ...Jim Thompson >>>>>>> >>>>>> If they're just photoconductors, you have to build up enough >>>>>> photocarriers to get a decent ON resistance. To reduce the amount of >>>>>> light required, you want a long carrier lifetime (which is easy to get >>>>>> in silicon, of course) but then you have to wait for them to recombine. >>>>>> >>>>>> Photoconductors also have twice full shot noise in the photocurrent >>>>>> portion--both the generation and recombination are stochastic. (The >>>>>> literature insists on making this somehow special by calling it 'GR >>>>>> noise' but the physics are pretty much the same as shot noise. >>>>>> >>>>>> Cheers >>>>>> >>>>>> Phil Hobbs >>>>> >>>>> Everyone has been calling them "FET's". Maybe they really are >>>>> "photoconductors", some other semiconductor equivalent to CdS?? >>>>> >>>>> ...Jim Thompson >>>> >>>> >>>> I wonder if Thompson is (still) smart enough to look at voltage:current curves >>>> and tell a resistor from a fet? >>>> >>>> http://www.fairchildsemi.com/ds/H1/H11F3M.pdf >>>> >>> >>> I think that photoconductors saturate like that too--there's a maximum >>> accessible drift rate, and a finite supply of carriers. Polycrystalline >>> CdS is a much crappier material. >>> >>> Cheers >>> >>> Phil Hobbs >> >> Yep. Someone needs to tell Ol' Bird Brain that the only difference is >> the gate control. I still puzzle over why Larkin has to continue this >> asshole behavior. Will he ever grow up? >> >> ...Jim Thompson >> > > Please leave me out of the flame war. I'm interested in technical topics > far more than in personalities. > > Cheers > > Phil Hobbs
Phil, you have my respect for that, unlike others who prefer to just fling dung (does it remind you of the chariot races at UBC?).
On Mar 10, 1:49=A0pm, George Herold <gher...@teachspin.com> wrote:
> On Mar 9, 4:54=A0pm, Phil Hobbs <pcdhSpamMeSensel...@electrooptical.net> > wrote:
> > On 3/9/2013 4:35 PM, Jim Thompson wrote: > > > > On Sat, 09 Mar 2013 16:29:09 -0500, Phil Hobbs > > > <pcdhSpamMeSensel...@electrooptical.net> wrote: > > > >> On 3/9/2013 4:18 PM, Jim Thompson wrote: > > >>> On Sat, 09 Mar 2013 21:12:25 +0000, John Devereux > > >>> <j...@devereux.me.uk> wrote: > > > >>>> Marte Schwarz <marte.schw...@gmx.de> writes: > > > >>>>> Hi John, > > > >>>>>>> Just think a little before flaming someone else, please. > > > >>>>>> Flaming? Really? First time I've been accused of that! > > > >>>>> Well? =A0You know how reliable Larkin's advice is >:-} > > > >>>>>> It was an honest question. Just thinking aloud. > > > >>>>> What a question? > > > >>>> Well you snipped it didn't you? > > > >>>>>>> opto-fets can never have a charge injection, because the charge=
they
> > >>>>>>> use to load the gate comes from the chanel that the charge flow=
s
> > >>>>>>> in. so the sum will allways be zero. I would say, this is as ob=
vious
> > >>>>>>> as Kirchhoffs law can be. > > > >>>>>> Well, I don't think it is that obvious. > > > >>>>> Where do you expect the injected charge comming from? > > > >>>> The voltage at the gate changes, relative to the other terminals. =
There
> > >>>> is a capacitance between the gate and the other terminals. dQ=3DC.=
dV.
> > > >>>>>> Even Jim "charge is always conserved" Thompson doesn't seem to t=
hink so
> > >>>>>> :) > > > >>>>> May be Jim woul tell his statement, too. > > > >>>>> I don't see any source for charge-injection. > > > >>>> The photodiode? (or whatever equivalent generates the change in ga=
te
> > >>>> voltage). > > > >>> There is no gate in an opto-FET. =A0Just a channel created by photo=
n
> > >>> impacts... and maybe that's the secret sauce... CONTINUOUS photon > > >>> impact is required to keep the FET on?? > > > >>> The pragmatist in me says, if opto-FET's were so wonderful, why am =
I
> > >>> not seeing them implemented as marvelous analog switches that are > > >>> sweeping the world with their stupendous performance ?:-) > > > >>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=
=A0 =A0 =A0 =A0 ...Jim Thompson
> > > >> Because they're 100 times too slow for general use, maybe. > > > > Maybe that's the answer... got to pile on a stream of photons before > > > anything happens. =A0Or too high an ON resistance? > > > If they're just photoconductors, you have to build up enough > > photocarriers to get a decent ON resistance. =A0To reduce the amount of > > light required, you want a long carrier lifetime (which is easy to get > > in silicon, of course) but then you have to wait for them to recombine. > > > Photoconductors also have twice full shot noise in the photocurrent > > portion--both the generation and recombination are stochastic. > > Ahh, (a light dawns) you've mentioned the double shot noise in > photoconductors, but I never got it. > > I've got this 'weird' dark noise from the reverse biased LED's I've > been playing with. =A0I'm pretty sure it's after pulsing of the > avalanche. =A0Which they attribute to some sort of traps in the avalnche > region. > There's an observable 'bunchiness' in the counts.
This shows up in SPADs - single photon avalanche diodes. The Milan mob have published useful stuff on that subject. -- Bill Sloman, Sydney
On 3/9/2013 11:17 PM, Ralph Barone wrote:
> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote: >> On 3/9/2013 7:18 PM, Jim Thompson wrote: >>> On Sat, 09 Mar 2013 18:39:30 -0500, Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> On 3/9/2013 5:43 PM, John Larkin wrote: >>>>> On Sat, 09 Mar 2013 15:05:26 -0700, Jim Thompson >>>>> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>>> >>>>>> On Sat, 09 Mar 2013 16:54:19 -0500, Phil Hobbs >>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>> >>>>>>> On 3/9/2013 4:35 PM, Jim Thompson wrote: >>>>>>>> On Sat, 09 Mar 2013 16:29:09 -0500, Phil Hobbs >>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>>>> >>>>>>>>> On 3/9/2013 4:18 PM, Jim Thompson wrote: >>>>>>>>>> On Sat, 09 Mar 2013 21:12:25 +0000, John Devereux >>>>>>>>>> <john@devereux.me.uk> wrote: >>>>>>>>>> >>>>>>>>>>> Marte Schwarz <marte.schwarz@gmx.de> writes: >>>>>>>>>>> >>>>>>>>>>>> Hi John, >>>>>>>>>>>> >>>>>>>>>>>>>> Just think a little before flaming someone else, please. >>>>>>>>>>>>> >>>>>>>>>>>>> Flaming? Really? First time I've been accused of that! >>>>>>>>>>>> >>>>>>>>>>>> Well? You know how reliable Larkin's advice is >:-} >>>>>>>>>>> >>>>>>>>>>>>> It was an honest question. Just thinking aloud. >>>>>>>>>>>> >>>>>>>>>>>> What a question? >>>>>>>>>>> >>>>>>>>>>> Well you snipped it didn't you? >>>>>>>>>>> >>>>>>>>>>>>>> opto-fets can never have a charge injection, because the charge they >>>>>>>>>>>>>> use to load the gate comes from the chanel that the charge flows >>>>>>>>>>>>>> in. so the sum will allways be zero. I would say, this is as obvious >>>>>>>>>>>>>> as Kirchhoffs law can be. >>>>>>>>>>>>> >>>>>>>>>>>>> Well, I don't think it is that obvious. >>>>>>>>>>>> >>>>>>>>>>>> Where do you expect the injected charge comming from? >>>>>>>>>>> >>>>>>>>>>> The voltage at the gate changes, relative to the other terminals. There >>>>>>>>>>> is a capacitance between the gate and the other terminals. dQ=C.dV. >>>>>>>>>>> >>>>>>>>>>>>> Even Jim "charge is always conserved" Thompson doesn't seem to think so >>>>>>>>>>>>> :) >>>>>>>>>>>> >>>>>>>>>>>> May be Jim woul tell his statement, too. >>>>>>>>>>>> >>>>>>>>>>>> I don't see any source for charge-injection. >>>>>>>>>>> >>>>>>>>>>> The photodiode? (or whatever equivalent generates the change in gate >>>>>>>>>>> voltage). >>>>>>>>>> >>>>>>>>>> There is no gate in an opto-FET. Just a channel created by photon >>>>>>>>>> impacts... and maybe that's the secret sauce... CONTINUOUS photon >>>>>>>>>> impact is required to keep the FET on?? >>>>>>>>>> >>>>>>>>>> The pragmatist in me says, if opto-FET's were so wonderful, why am I >>>>>>>>>> not seeing them implemented as marvelous analog switches that are >>>>>>>>>> sweeping the world with their stupendous performance ?:-) >>>>>>>>>> >>>>>>>>>> ...Jim Thompson >>>>>>>>>> >>>>>>>>> >>>>>>>>> Because they're 100 times too slow for general use, maybe. >>>>>>>>> >>>>>>>>> Cheers >>>>>>>>> >>>>>>>>> Phil Hobbs >>>>>>>> >>>>>>>> Maybe that's the answer... got to pile on a stream of photons before >>>>>>>> anything happens. Or too high an ON resistance? >>>>>>>> >>>>>>>> ...Jim Thompson >>>>>>>> >>>>>>> If they're just photoconductors, you have to build up enough >>>>>>> photocarriers to get a decent ON resistance. To reduce the amount of >>>>>>> light required, you want a long carrier lifetime (which is easy to get >>>>>>> in silicon, of course) but then you have to wait for them to recombine. >>>>>>> >>>>>>> Photoconductors also have twice full shot noise in the photocurrent >>>>>>> portion--both the generation and recombination are stochastic. (The >>>>>>> literature insists on making this somehow special by calling it 'GR >>>>>>> noise' but the physics are pretty much the same as shot noise. >>>>>>> >>>>>>> Cheers >>>>>>> >>>>>>> Phil Hobbs >>>>>> >>>>>> Everyone has been calling them "FET's". Maybe they really are >>>>>> "photoconductors", some other semiconductor equivalent to CdS?? >>>>>> >>>>>> ...Jim Thompson >>>>> >>>>> >>>>> I wonder if Thompson is (still) smart enough to look at voltage:current curves >>>>> and tell a resistor from a fet? >>>>> >>>>> http://www.fairchildsemi.com/ds/H1/H11F3M.pdf >>>>> >>>> >>>> I think that photoconductors saturate like that too--there's a maximum >>>> accessible drift rate, and a finite supply of carriers. Polycrystalline >>>> CdS is a much crappier material. >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> Yep. Someone needs to tell Ol' Bird Brain that the only difference is >>> the gate control. I still puzzle over why Larkin has to continue this >>> asshole behavior. Will he ever grow up? >>> >>> ...Jim Thompson >>> >> >> Please leave me out of the flame war. I'm interested in technical topics >> far more than in personalities. >> >> Cheers >> >> Phil Hobbs > > > Phil, you have my respect for that, unlike others who prefer to just fling > dung (does it remind you of the chariot races at UBC?). >
I never went to the chariot races. IIRC they were (a) an engineering thing, and (b) before my time. I heard about them from my big brother, who was in CS but hung out with a bunch of gears. They weren't the most welcoming crowd. 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 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
> On 3/9/2013 11:17 PM, Ralph Barone wrote: >> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> On 3/9/2013 7:18 PM, Jim Thompson wrote: >>>> On Sat, 09 Mar 2013 18:39:30 -0500, Phil Hobbs >>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>> >>>>> On 3/9/2013 5:43 PM, John Larkin wrote: >>>>>> On Sat, 09 Mar 2013 15:05:26 -0700, Jim Thompson >>>>>> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>>>> >>>>>>> On Sat, 09 Mar 2013 16:54:19 -0500, Phil Hobbs >>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>>> >>>>>>>> On 3/9/2013 4:35 PM, Jim Thompson wrote: >>>>>>>>> On Sat, 09 Mar 2013 16:29:09 -0500, Phil Hobbs >>>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>>>>> >>>>>>>>>> On 3/9/2013 4:18 PM, Jim Thompson wrote: >>>>>>>>>>> On Sat, 09 Mar 2013 21:12:25 +0000, John Devereux >>>>>>>>>>> <john@devereux.me.uk> wrote: >>>>>>>>>>> >>>>>>>>>>>> Marte Schwarz <marte.schwarz@gmx.de> writes: >>>>>>>>>>>> >>>>>>>>>>>>> Hi John, >>>>>>>>>>>>> >>>>>>>>>>>>>>> Just think a little before flaming someone else, please. >>>>>>>>>>>>>> >>>>>>>>>>>>>> Flaming? Really? First time I've been accused of that! >>>>>>>>>>>>> >>>>>>>>>>>>> Well? You know how reliable Larkin's advice is >:-} >>>>>>>>>>>> >>>>>>>>>>>>>> It was an honest question. Just thinking aloud. >>>>>>>>>>>>> >>>>>>>>>>>>> What a question? >>>>>>>>>>>> >>>>>>>>>>>> Well you snipped it didn't you? >>>>>>>>>>>> >>>>>>>>>>>>>>> opto-fets can never have a charge injection, because the charge they >>>>>>>>>>>>>>> use to load the gate comes from the chanel that the charge flows >>>>>>>>>>>>>>> in. so the sum will allways be zero. I would say, this is as obvious >>>>>>>>>>>>>>> as Kirchhoffs law can be. >>>>>>>>>>>>>> >>>>>>>>>>>>>> Well, I don't think it is that obvious. >>>>>>>>>>>>> >>>>>>>>>>>>> Where do you expect the injected charge comming from? >>>>>>>>>>>> >>>>>>>>>>>> The voltage at the gate changes, relative to the other terminals. There >>>>>>>>>>>> is a capacitance between the gate and the other terminals. dQ=C.dV. >>>>>>>>>>>> >>>>>>>>>>>>>> Even Jim "charge is always conserved" Thompson doesn't seem to think so >>>>>>>>>>>>>> :) >>>>>>>>>>>>> >>>>>>>>>>>>> May be Jim woul tell his statement, too. >>>>>>>>>>>>> >>>>>>>>>>>>> I don't see any source for charge-injection. >>>>>>>>>>>> >>>>>>>>>>>> The photodiode? (or whatever equivalent generates the change in gate >>>>>>>>>>>> voltage). >>>>>>>>>>> >>>>>>>>>>> There is no gate in an opto-FET. Just a channel created by photon >>>>>>>>>>> impacts... and maybe that's the secret sauce... CONTINUOUS photon >>>>>>>>>>> impact is required to keep the FET on?? >>>>>>>>>>> >>>>>>>>>>> The pragmatist in me says, if opto-FET's were so wonderful, why am I >>>>>>>>>>> not seeing them implemented as marvelous analog switches that are >>>>>>>>>>> sweeping the world with their stupendous performance ?:-) >>>>>>>>>>> >>>>>>>>>>> ...Jim Thompson >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Because they're 100 times too slow for general use, maybe. >>>>>>>>>> >>>>>>>>>> Cheers >>>>>>>>>> >>>>>>>>>> Phil Hobbs >>>>>>>>> >>>>>>>>> Maybe that's the answer... got to pile on a stream of photons before >>>>>>>>> anything happens. Or too high an ON resistance? >>>>>>>>> >>>>>>>>> ...Jim Thompson >>>>>>>>> >>>>>>>> If they're just photoconductors, you have to build up enough >>>>>>>> photocarriers to get a decent ON resistance. To reduce the amount of >>>>>>>> light required, you want a long carrier lifetime (which is easy to get >>>>>>>> in silicon, of course) but then you have to wait for them to recombine. >>>>>>>> >>>>>>>> Photoconductors also have twice full shot noise in the photocurrent >>>>>>>> portion--both the generation and recombination are stochastic. (The >>>>>>>> literature insists on making this somehow special by calling it 'GR >>>>>>>> noise' but the physics are pretty much the same as shot noise. >>>>>>>> >>>>>>>> Cheers >>>>>>>> >>>>>>>> Phil Hobbs >>>>>>> >>>>>>> Everyone has been calling them "FET's". Maybe they really are >>>>>>> "photoconductors", some other semiconductor equivalent to CdS?? >>>>>>> >>>>>>> ...Jim Thompson >>>>>> >>>>>> >>>>>> I wonder if Thompson is (still) smart enough to look at voltage:current curves >>>>>> and tell a resistor from a fet? >>>>>> >>>>>> http://www.fairchildsemi.com/ds/H1/H11F3M.pdf >>>>>> >>>>> >>>>> I think that photoconductors saturate like that too--there's a maximum >>>>> accessible drift rate, and a finite supply of carriers. Polycrystalline >>>>> CdS is a much crappier material. >>>>> >>>>> Cheers >>>>> >>>>> Phil Hobbs >>>> >>>> Yep. Someone needs to tell Ol' Bird Brain that the only difference is >>>> the gate control. I still puzzle over why Larkin has to continue this >>>> asshole behavior. Will he ever grow up? >>>> >>>> ...Jim Thompson >>>> >>> >>> Please leave me out of the flame war. I'm interested in technical topics >>> far more than in personalities. >>> >>> Cheers >>> >>> Phil Hobbs >> >> >> Phil, you have my respect for that, unlike others who prefer to just fling >> dung (does it remind you of the chariot races at UBC?). >> > > I never went to the chariot races. IIRC they were (a) an engineering > thing, and (b) before my time. I heard about them from my big brother, > who was in CS but hung out with a bunch of gears. They weren't the most welcoming crowd. > > Cheers > > Phil Hobbs
Weird... I remember them and I'm pretty certain I was there after you. However, I also avoided the chariot race. Entering into a "race to the bottom" just didn't seem like a good idea.
On 3/10/2013 1:38 PM, Ralph Barone wrote:
> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote: >> On 3/9/2013 11:17 PM, Ralph Barone wrote: >>> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>> On 3/9/2013 7:18 PM, Jim Thompson wrote: >>>>> On Sat, 09 Mar 2013 18:39:30 -0500, Phil Hobbs >>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>> >>>>>> On 3/9/2013 5:43 PM, John Larkin wrote: >>>>>>> On Sat, 09 Mar 2013 15:05:26 -0700, Jim Thompson >>>>>>> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>>>>> >>>>>>>> On Sat, 09 Mar 2013 16:54:19 -0500, Phil Hobbs >>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>>>> >>>>>>>>> On 3/9/2013 4:35 PM, Jim Thompson wrote: >>>>>>>>>> On Sat, 09 Mar 2013 16:29:09 -0500, Phil Hobbs >>>>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>>>>>> >>>>>>>>>>> On 3/9/2013 4:18 PM, Jim Thompson wrote: >>>>>>>>>>>> On Sat, 09 Mar 2013 21:12:25 +0000, John Devereux >>>>>>>>>>>> <john@devereux.me.uk> wrote: >>>>>>>>>>>> >>>>>>>>>>>>> Marte Schwarz <marte.schwarz@gmx.de> writes: >>>>>>>>>>>>> >>>>>>>>>>>>>> Hi John, >>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Just think a little before flaming someone else, please. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Flaming? Really? First time I've been accused of that! >>>>>>>>>>>>>> >>>>>>>>>>>>>> Well? You know how reliable Larkin's advice is >:-} >>>>>>>>>>>>> >>>>>>>>>>>>>>> It was an honest question. Just thinking aloud. >>>>>>>>>>>>>> >>>>>>>>>>>>>> What a question? >>>>>>>>>>>>> >>>>>>>>>>>>> Well you snipped it didn't you? >>>>>>>>>>>>> >>>>>>>>>>>>>>>> opto-fets can never have a charge injection, because the charge they >>>>>>>>>>>>>>>> use to load the gate comes from the chanel that the charge flows >>>>>>>>>>>>>>>> in. so the sum will allways be zero. I would say, this is as obvious >>>>>>>>>>>>>>>> as Kirchhoffs law can be. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Well, I don't think it is that obvious. >>>>>>>>>>>>>> >>>>>>>>>>>>>> Where do you expect the injected charge comming from? >>>>>>>>>>>>> >>>>>>>>>>>>> The voltage at the gate changes, relative to the other terminals. There >>>>>>>>>>>>> is a capacitance between the gate and the other terminals. dQ=C.dV. >>>>>>>>>>>>> >>>>>>>>>>>>>>> Even Jim "charge is always conserved" Thompson doesn't seem to think so >>>>>>>>>>>>>>> :) >>>>>>>>>>>>>> >>>>>>>>>>>>>> May be Jim woul tell his statement, too. >>>>>>>>>>>>>> >>>>>>>>>>>>>> I don't see any source for charge-injection. >>>>>>>>>>>>> >>>>>>>>>>>>> The photodiode? (or whatever equivalent generates the change in gate >>>>>>>>>>>>> voltage). >>>>>>>>>>>> >>>>>>>>>>>> There is no gate in an opto-FET. Just a channel created by photon >>>>>>>>>>>> impacts... and maybe that's the secret sauce... CONTINUOUS photon >>>>>>>>>>>> impact is required to keep the FET on?? >>>>>>>>>>>> >>>>>>>>>>>> The pragmatist in me says, if opto-FET's were so wonderful, why am I >>>>>>>>>>>> not seeing them implemented as marvelous analog switches that are >>>>>>>>>>>> sweeping the world with their stupendous performance ?:-) >>>>>>>>>>>> >>>>>>>>>>>> ...Jim Thompson >>>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> Because they're 100 times too slow for general use, maybe. >>>>>>>>>>> >>>>>>>>>>> Cheers >>>>>>>>>>> >>>>>>>>>>> Phil Hobbs >>>>>>>>>> >>>>>>>>>> Maybe that's the answer... got to pile on a stream of photons before >>>>>>>>>> anything happens. Or too high an ON resistance? >>>>>>>>>> >>>>>>>>>> ...Jim Thompson >>>>>>>>>> >>>>>>>>> If they're just photoconductors, you have to build up enough >>>>>>>>> photocarriers to get a decent ON resistance. To reduce the amount of >>>>>>>>> light required, you want a long carrier lifetime (which is easy to get >>>>>>>>> in silicon, of course) but then you have to wait for them to recombine. >>>>>>>>> >>>>>>>>> Photoconductors also have twice full shot noise in the photocurrent >>>>>>>>> portion--both the generation and recombination are stochastic. (The >>>>>>>>> literature insists on making this somehow special by calling it 'GR >>>>>>>>> noise' but the physics are pretty much the same as shot noise. >>>>>>>>> >>>>>>>>> Cheers >>>>>>>>> >>>>>>>>> Phil Hobbs >>>>>>>> >>>>>>>> Everyone has been calling them "FET's". Maybe they really are >>>>>>>> "photoconductors", some other semiconductor equivalent to CdS?? >>>>>>>> >>>>>>>> ...Jim Thompson >>>>>>> >>>>>>> >>>>>>> I wonder if Thompson is (still) smart enough to look at voltage:current curves >>>>>>> and tell a resistor from a fet? >>>>>>> >>>>>>> http://www.fairchildsemi.com/ds/H1/H11F3M.pdf >>>>>>> >>>>>> >>>>>> I think that photoconductors saturate like that too--there's a maximum >>>>>> accessible drift rate, and a finite supply of carriers. Polycrystalline >>>>>> CdS is a much crappier material. >>>>>> >>>>>> Cheers >>>>>> >>>>>> Phil Hobbs >>>>> >>>>> Yep. Someone needs to tell Ol' Bird Brain that the only difference is >>>>> the gate control. I still puzzle over why Larkin has to continue this >>>>> asshole behavior. Will he ever grow up? >>>>> >>>>> ...Jim Thompson >>>>> >>>> >>>> Please leave me out of the flame war. I'm interested in technical topics >>>> far more than in personalities. >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> >>> Phil, you have my respect for that, unlike others who prefer to just fling >>> dung (does it remind you of the chariot races at UBC?). >>> >> >> I never went to the chariot races. IIRC they were (a) an engineering >> thing, and (b) before my time. I heard about them from my big brother, >> who was in CS but hung out with a bunch of gears. They weren't the most welcoming crowd. >> >> Cheers >> >> Phil Hobbs > > > Weird... I remember them and I'm pretty certain I was there after you. > However, I also avoided the chariot race. Entering into a "race to the > bottom" just didn't seem like a good idea. >
I graduated in '81. You? 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 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
> On 3/10/2013 1:38 PM, Ralph Barone wrote: >> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> On 3/9/2013 11:17 PM, Ralph Barone wrote: >>>> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>> On 3/9/2013 7:18 PM, Jim Thompson wrote: >>>>>> On Sat, 09 Mar 2013 18:39:30 -0500, Phil Hobbs >>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>> >>>>>>> On 3/9/2013 5:43 PM, John Larkin wrote: >>>>>>>> On Sat, 09 Mar 2013 15:05:26 -0700, Jim Thompson >>>>>>>> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >>>>>>>> >>>>>>>>> On Sat, 09 Mar 2013 16:54:19 -0500, Phil Hobbs >>>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>>>>> >>>>>>>>>> On 3/9/2013 4:35 PM, Jim Thompson wrote: >>>>>>>>>>> On Sat, 09 Mar 2013 16:29:09 -0500, Phil Hobbs >>>>>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>>>>>>> >>>>>>>>>>>> On 3/9/2013 4:18 PM, Jim Thompson wrote: >>>>>>>>>>>>> On Sat, 09 Mar 2013 21:12:25 +0000, John Devereux >>>>>>>>>>>>> <john@devereux.me.uk> wrote: >>>>>>>>>>>>> >>>>>>>>>>>>>> Marte Schwarz <marte.schwarz@gmx.de> writes: >>>>>>>>>>>>>> >>>>>>>>>>>>>>> Hi John, >>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Just think a little before flaming someone else, please. >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Flaming? Really? First time I've been accused of that! >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Well? You know how reliable Larkin's advice is >:-} >>>>>>>>>>>>>> >>>>>>>>>>>>>>>> It was an honest question. Just thinking aloud. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> What a question? >>>>>>>>>>>>>> >>>>>>>>>>>>>> Well you snipped it didn't you? >>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> opto-fets can never have a charge injection, because the charge they >>>>>>>>>>>>>>>>> use to load the gate comes from the chanel that the charge flows >>>>>>>>>>>>>>>>> in. so the sum will allways be zero. I would say, this is as obvious >>>>>>>>>>>>>>>>> as Kirchhoffs law can be. >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Well, I don't think it is that obvious. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Where do you expect the injected charge comming from? >>>>>>>>>>>>>> >>>>>>>>>>>>>> The voltage at the gate changes, relative to the other terminals. There >>>>>>>>>>>>>> is a capacitance between the gate and the other terminals. dQ=C.dV. >>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Even Jim "charge is always conserved" Thompson doesn't seem to think so >>>>>>>>>>>>>>>> :) >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> May be Jim woul tell his statement, too. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> I don't see any source for charge-injection. >>>>>>>>>>>>>> >>>>>>>>>>>>>> The photodiode? (or whatever equivalent generates the change in gate >>>>>>>>>>>>>> voltage). >>>>>>>>>>>>> >>>>>>>>>>>>> There is no gate in an opto-FET. Just a channel created by photon >>>>>>>>>>>>> impacts... and maybe that's the secret sauce... CONTINUOUS photon >>>>>>>>>>>>> impact is required to keep the FET on?? >>>>>>>>>>>>> >>>>>>>>>>>>> The pragmatist in me says, if opto-FET's were so wonderful, why am I >>>>>>>>>>>>> not seeing them implemented as marvelous analog switches that are >>>>>>>>>>>>> sweeping the world with their stupendous performance ?:-) >>>>>>>>>>>>> >>>>>>>>>>>>> ...Jim Thompson >>>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Because they're 100 times too slow for general use, maybe. >>>>>>>>>>>> >>>>>>>>>>>> Cheers >>>>>>>>>>>> >>>>>>>>>>>> Phil Hobbs >>>>>>>>>>> >>>>>>>>>>> Maybe that's the answer... got to pile on a stream of photons before >>>>>>>>>>> anything happens. Or too high an ON resistance? >>>>>>>>>>> >>>>>>>>>>> ...Jim Thompson >>>>>>>>>>> >>>>>>>>>> If they're just photoconductors, you have to build up enough >>>>>>>>>> photocarriers to get a decent ON resistance. To reduce the amount of >>>>>>>>>> light required, you want a long carrier lifetime (which is easy to get >>>>>>>>>> in silicon, of course) but then you have to wait for them to recombine. >>>>>>>>>> >>>>>>>>>> Photoconductors also have twice full shot noise in the photocurrent >>>>>>>>>> portion--both the generation and recombination are stochastic. (The >>>>>>>>>> literature insists on making this somehow special by calling it 'GR >>>>>>>>>> noise' but the physics are pretty much the same as shot noise. >>>>>>>>>> >>>>>>>>>> Cheers >>>>>>>>>> >>>>>>>>>> Phil Hobbs >>>>>>>>> >>>>>>>>> Everyone has been calling them "FET's". Maybe they really are >>>>>>>>> "photoconductors", some other semiconductor equivalent to CdS?? >>>>>>>>> >>>>>>>>> ...Jim Thompson >>>>>>>> >>>>>>>> >>>>>>>> I wonder if Thompson is (still) smart enough to look at voltage:current curves >>>>>>>> and tell a resistor from a fet? >>>>>>>> >>>>>>>> http://www.fairchildsemi.com/ds/H1/H11F3M.pdf >>>>>>>> >>>>>>> >>>>>>> I think that photoconductors saturate like that too--there's a maximum >>>>>>> accessible drift rate, and a finite supply of carriers. Polycrystalline >>>>>>> CdS is a much crappier material. >>>>>>> >>>>>>> Cheers >>>>>>> >>>>>>> Phil Hobbs >>>>>> >>>>>> Yep. Someone needs to tell Ol' Bird Brain that the only difference is >>>>>> the gate control. I still puzzle over why Larkin has to continue this >>>>>> asshole behavior. Will he ever grow up? >>>>>> >>>>>> ...Jim Thompson >>>>>> >>>>> >>>>> Please leave me out of the flame war. I'm interested in technical topics >>>>> far more than in personalities. >>>>> >>>>> Cheers >>>>> >>>>> Phil Hobbs >>>> >>>> >>>> Phil, you have my respect for that, unlike others who prefer to just fling >>>> dung (does it remind you of the chariot races at UBC?). >>>> >>> >>> I never went to the chariot races. IIRC they were (a) an engineering >>> thing, and (b) before my time. I heard about them from my big brother, >>> who was in CS but hung out with a bunch of gears. They weren't the most welcoming crowd. >>> >>> Cheers >>> >>> Phil Hobbs >> >> >> Weird... I remember them and I'm pretty certain I was there after you. >> However, I also avoided the chariot race. Entering into a "race to the >> bottom" just didn't seem like a good idea. >> > > I graduated in '81. You? > > Cheers > > Phil Hobbs
1988. EE.