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lock-in amplifier

Started by scot March 5, 2013
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 -- 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
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 -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On 3/9/2013 5:05 PM, Jim Thompson 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 >
Dunno. Nobody else has used silicon photoconductors in yonks, so maybe Marketing decided to make it simpler for folks. Or maybe they work in a completely different way. (My money is on their being a silicon version of a Vactrol.) 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
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 -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
On Sat, 09 Mar 2013 17:16:57 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 3/9/2013 5:05 PM, Jim Thompson 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 >> >Dunno. Nobody else has used silicon photoconductors in yonks, so maybe >Marketing decided to make it simpler for folks. Or maybe they work in a >completely different way. (My money is on their being a silicon version >of a Vactrol.) > >Cheers > >Phil Hobbs
CdS makes for nice audio AGC >:-} ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
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 -- 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
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 -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
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 -- 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
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 t=
hey
> >>>>>>> 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 obvi=
ous
> >>>>>>> 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. Th=
ere
> >>>> is a capacitance between the gate and the other terminals. dQ=3DC.dV=
.
> > >>>>>> Even Jim "charge is always conserved" Thompson doesn't seem to thi=
nk 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. =A0Just 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 ?:-) > > >>> =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. > > >> Cheers > > >> Phil Hobbs > > > Maybe that's the answer... got to pile on a stream of photons before > > anything happens. =A0Or too high an ON resistance? > > > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=
=A0 =A0 =A0...Jim Thompson
> > 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. I'm pretty sure it's after pulsing of the avalanche. Which they attribute to some sort of traps in the avalnche region. There's an observable 'bunchiness' in the counts. George H. (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 > > -- > 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 nethttp://electrooptical.net- Hide quoted tex=
t -
> > - Show quoted text -
On Sat, 09 Mar 2013 19:48:27 -0500, 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
Same here. But Larkin just _will_not_ let it go :-( ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.