Photodiode SPICE models?
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From: Jim Thompson on 28 Oct 2009 12:56 On Wed, 28 Oct 2009 12:40:25 -0400, Phil Hobbs <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >Yuri Belenky wrote: >> Phil Hobbs wrote: >>> Dear all: >>> >>> I'm on a bit of a roll with TIA designs at the moment, but I've just >>> been using current sources with caps in parallel to model >>> fully-depleted photodiodes, and I need a better model to hack up. >>> >>> The LTSPICE Yahoo group's files area is broken at the moment. Do any >>> of you have a decent PD model with 4 terminals (anode, cathode, and >>> two to represent the light input)? >>> >>> Nonlinear capacitance would be a plus but isn't required. >>> >>> (I've used SPICE more in the last two weeks than in my entire previous >>> career--I'm more of an algebra guy when it comes to circuit design, >>> but some things really need sims.) >>> >>> Thanks >>> >>> Phil Hobbs >>> >> >> I've used this model several years ago (MRD500 photodiode): >> >> --- model starts here ------------------------ >> >> * PSpice Model Editor - Version 10.5.0 >> >> *$ >> ******************************************************************************* >> >> * A = Anode >> * C = Cathode >> * P = (light)Power as voltage input >> ..SUBCKT MRD500 A C P PARAMS: Spec=1.0 Sensy=0.3894 >> * MRD500 from Motorola * RAP 7/97 >> DPD A C PhotoDet >> RDUMMY P 0 1G >> GPD C A TABLE {V(P)* Spec * Sensy} (0,0) (1,1) >> ..MODEL PhotoDet D IS=1.02p RS=10 N=0.841978 BV=100 IBV=1u >> + CJO=6.03p VJ=0.202968 M=0.146605 TT=1n ISR=17p >> ..ends >> *$ >> >> --- end of model ------------------------------ >> >> Let me know if you need it as OrCAD library file. >> >> Yuri. >Thanks. > >A couple of people have sent models (Thanks, guys), but there is one >remaining puzzle: shot noise. I'd have thought that the .asc file below >would generate exactly the shot noise of Iphoto--diodes have full shot >noise, so connecting it to a DC current source should turn D1 into a >full shot noise current source, which ought to get picked off via the >infinite capacitor into the 0V source, and so into the behavioural >current source at the output. > >However, it doesn't do anything of the sort--it's all over the map. >Different diodes and diode-connected transistors give all sorts of >different values. > >Any ideas what's going on? One possible clue is that any resistance at >all in series with V2 reduces the noise enormously. > >Thanks > >Phil Hobbs Phil, Unfortunately, transient and DC simulations won't/don't show noise. A .AC analysis should show noise. I don't know the set-ups for LTspice. ..MODEL PhotoDet is likely lacking in noise coefficients, so it's defaulting to who knows what. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | 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 | "Somebody had to build the ceiling... before Michelangelo could go to work." - John Ratzenberger http://analog-innovations.com/SED/Somebody_had_to_build_the_ceiling.pdf
From: Phil Hobbs on 28 Oct 2009 13:02 Jim Thompson wrote: > On Wed, 28 Oct 2009 12:40:25 -0400, Phil Hobbs > <pcdhSpamMeSenseless(a)electrooptical.net> wrote: > >> Yuri Belenky wrote: >>> Phil Hobbs wrote: >>>> Dear all: >>>> >>>> I'm on a bit of a roll with TIA designs at the moment, but I've just >>>> been using current sources with caps in parallel to model >>>> fully-depleted photodiodes, and I need a better model to hack up. >>>> >>>> The LTSPICE Yahoo group's files area is broken at the moment. Do any >>>> of you have a decent PD model with 4 terminals (anode, cathode, and >>>> two to represent the light input)? >>>> >>>> Nonlinear capacitance would be a plus but isn't required. >>>> >>>> (I've used SPICE more in the last two weeks than in my entire previous >>>> career--I'm more of an algebra guy when it comes to circuit design, >>>> but some things really need sims.) >>>> >>>> Thanks >>>> >>>> Phil Hobbs >>>> >>> I've used this model several years ago (MRD500 photodiode): >>> >>> --- model starts here ------------------------ >>> >>> * PSpice Model Editor - Version 10.5.0 >>> >>> *$ >>> ******************************************************************************* >>> >>> * A = Anode >>> * C = Cathode >>> * P = (light)Power as voltage input >>> ..SUBCKT MRD500 A C P PARAMS: Spec=1.0 Sensy=0.3894 >>> * MRD500 from Motorola * RAP 7/97 >>> DPD A C PhotoDet >>> RDUMMY P 0 1G >>> GPD C A TABLE {V(P)* Spec * Sensy} (0,0) (1,1) >>> ..MODEL PhotoDet D IS=1.02p RS=10 N=0.841978 BV=100 IBV=1u >>> + CJO=6.03p VJ=0.202968 M=0.146605 TT=1n ISR=17p >>> ..ends >>> *$ >>> >>> --- end of model ------------------------------ >>> >>> Let me know if you need it as OrCAD library file. >>> >>> Yuri. >> Thanks. >> >> A couple of people have sent models (Thanks, guys), but there is one >> remaining puzzle: shot noise. I'd have thought that the .asc file below >> would generate exactly the shot noise of Iphoto--diodes have full shot >> noise, so connecting it to a DC current source should turn D1 into a >> full shot noise current source, which ought to get picked off via the >> infinite capacitor into the 0V source, and so into the behavioural >> current source at the output. >> >> However, it doesn't do anything of the sort--it's all over the map. >> Different diodes and diode-connected transistors give all sorts of >> different values. >> >> Any ideas what's going on? One possible clue is that any resistance at >> all in series with V2 reduces the noise enormously. >> >> Thanks >> >> Phil Hobbs > > Phil, > > Unfortunately, transient and DC simulations won't/don't show noise. > > A .AC analysis should show noise. I don't know the set-ups for > LTspice. > > ..MODEL PhotoDet is likely lacking in noise coefficients, so it's > defaulting to who knows what. > > ...Jim Thompson Jim, Thanks. I should have been clearer I expect--I'm trying to do a .noise simulation, and I see the diode noise but it's anywhere from 1% to 75% of the correct shot noise value depending on the device and the value of Iphoto. Replacing the diode with a 1N5817 gets nearly the right answer at 1 mA but is hopelessly low at 1 uA. Using a diode-connected BFT25A (B-C shorted) gives results about 10 dB too low at all photocurrents. I saw this exact technique recommended in a paper. There's obviously something I'm doing wrong, but I don't know what it is. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: Phil Hobbs on 28 Oct 2009 13:06 Phil Hobbs wrote: > Jim Thompson wrote: >> On Wed, 28 Oct 2009 12:40:25 -0400, Phil Hobbs >> <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >> >>> Yuri Belenky wrote: >>>> Phil Hobbs wrote: >>>>> Dear all: >>>>> >>>>> I'm on a bit of a roll with TIA designs at the moment, but I've >>>>> just been using current sources with caps in parallel to model >>>>> fully-depleted photodiodes, and I need a better model to hack up. >>>>> >>>>> The LTSPICE Yahoo group's files area is broken at the moment. Do >>>>> any of you have a decent PD model with 4 terminals (anode, cathode, >>>>> and two to represent the light input)? >>>>> >>>>> Nonlinear capacitance would be a plus but isn't required. >>>>> >>>>> (I've used SPICE more in the last two weeks than in my entire >>>>> previous career--I'm more of an algebra guy when it comes to >>>>> circuit design, but some things really need sims.) >>>>> >>>>> Thanks >>>>> >>>>> Phil Hobbs >>>>> < Yuri's model snipped> >>> Thanks. >>> >>> A couple of people have sent models (Thanks, guys), but there is one >>> remaining puzzle: shot noise. I'd have thought that the .asc file >>> below would generate exactly the shot noise of Iphoto--diodes have >>> full shot noise, so connecting it to a DC current source should turn >>> D1 into a full shot noise current source, which ought to get picked >>> off via the infinite capacitor into the 0V source, and so into the >>> behavioural current source at the output. >>> >>> However, it doesn't do anything of the sort--it's all over the map. >>> Different diodes and diode-connected transistors give all sorts of >>> different values. >>> >>> Any ideas what's going on? One possible clue is that any resistance >>> at all in series with V2 reduces the noise enormously. >>> >>> Thanks >>> >>> Phil Hobbs >> >> Phil, >> >> Unfortunately, transient and DC simulations won't/don't show noise. >> >> A .AC analysis should show noise. I don't know the set-ups for >> LTspice. >> >> ..MODEL PhotoDet is likely lacking in noise coefficients, so it's >> defaulting to who knows what. >> >> ...Jim Thompson > > Jim, > > Thanks. I should have been clearer I expect--I'm trying to do a .noise > simulation, and I see the diode noise but it's anywhere from 1% to 75% > of the correct shot noise value depending on the device and the value of > Iphoto. Replacing the diode with a 1N5817 gets nearly the right answer > at 1 mA but is hopelessly low at 1 uA. Using a diode-connected BFT25A > (B-C shorted) gives results about 10 dB too low at all photocurrents. > > I saw this exact technique recommended in a paper. There's obviously > something I'm doing wrong, but I don't know what it is. > > Cheers > > Phil Hobbs > Ah, I see where the confusion arose--I'm not using Yuri's circuit, but the one I attached. Here it is again inline. Still weird. Cheers Phil --------- ShotNoiseGen.asc ------------------- Version 4 SHEET 1 880 732 WIRE 80 32 16 32 WIRE 160 32 80 32 WIRE 400 32 288 32 WIRE 16 48 16 32 WIRE 160 48 160 32 WIRE 80 64 80 32 WIRE 400 64 400 32 WIRE 288 96 288 32 WIRE 160 128 160 112 WIRE 16 160 16 128 WIRE 80 160 80 128 WIRE 288 208 288 176 WIRE 400 208 400 144 WIRE 400 208 288 208 FLAG 16 160 0 FLAG 400 32 Output FLAG 80 160 0 FLAG 160 208 0 FLAG 288 208 0 SYMBOL res 384 48 R0 SYMATTR InstName R1 SYMATTR Value 10k SYMBOL current 16 128 R180 WINDOW 0 24 88 Left 0 WINDOW 3 24 0 Left 0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName I1 SYMATTR Value {Iphoto} SYMBOL voltage 160 112 R0 WINDOW 123 0 0 Left 0 WINDOW 39 24 118 Left 0 SYMATTR SpiceLine Rser=0 SYMATTR InstName V2 SYMATTR Value 0 SYMBOL cap 144 48 R0 SYMATTR InstName C2 SYMATTR Value 1G SYMATTR SpiceLine Rser=1f Lser=1f Rpar=1T SYMBOL bi2 288 176 M180 WINDOW 0 24 88 Left 0 WINDOW 3 24 0 Left 0 SYMATTR InstName B2 SYMATTR Value I=Iphoto+I(V2) SYMBOL diode 64 64 R0 SYMATTR InstName D1 SYMATTR Value Dshot TEXT -216 128 Left 0 !.param Iphoto=1m TEXT -216 160 Left 0 !.noise V(Output) I1 dec 10 1 1g TEXT -200 104 Left 0 !.model Dshot D() -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: George Herold on 28 Oct 2009 13:25 On Oct 28, 12:40 pm, Phil Hobbs <pcdhSpamMeSensel...(a)electrooptical.net> wrote: > Yuri Belenky wrote: > > Phil Hobbs wrote: > >> Dear all: > > >> I'm on a bit of a roll with TIA designs at the moment, but I've just > >> been using current sources with caps in parallel to model > >> fully-depleted photodiodes, and I need a better model to hack up. > > >> The LTSPICE Yahoo group's files area is broken at the moment. Do any > >> of you have a decent PD model with 4 terminals (anode, cathode, and > >> two to represent the light input)? > > >> Nonlinear capacitance would be a plus but isn't required. > > >> (I've used SPICE more in the last two weeks than in my entire previous > >> career--I'm more of an algebra guy when it comes to circuit design, > >> but some things really need sims.) > > >> Thanks > > >> Phil Hobbs > > > I've used this model several years ago (MRD500 photodiode): > > > --- model starts here ------------------------ > > > * PSpice Model Editor - Version 10.5.0 > > > *$ > > ******************************************************************************* > > > * A = Anode > > * C = Cathode > > * P = (light)Power as voltage input > > ..SUBCKT MRD500 A C P PARAMS: Spec=1.0 Sensy=0.3894 > > * MRD500 from Motorola * RAP 7/97 > > DPD A C PhotoDet > > RDUMMY P 0 1G > > GPD C A TABLE {V(P)* Spec * Sensy} (0,0) (1,1) > > ..MODEL PhotoDet D IS=1.02p RS=10 N=0.841978 BV=100 IBV=1u > > + CJO=6.03p VJ=0.202968 M=0.146605 TT=1n ISR=17p > > ..ends > > *$ > > > --- end of model ------------------------------ > > > Let me know if you need it as OrCAD library file. > > > Yuri. > > Thanks. > > A couple of people have sent models (Thanks, guys), but there is one > remaining puzzle: shot noise. I'd have thought that the .asc file below > would generate exactly the shot noise of Iphoto--diodes have full shot > noise, so connecting it to a DC current source should turn D1 into a > full shot noise current source, which ought to get picked off via the > infinite capacitor into the 0V source, and so into the behavioural > current source at the output. > > However, it doesn't do anything of the sort--it's all over the map. > Different diodes and diode-connected transistors give all sorts of > different values. > > Any ideas what's going on? One possible clue is that any resistance at > all in series with V2 reduces the noise enormously. > > Thanks > > Phil Hobbs > > -- > Dr Philip C D Hobbs > Principal > ElectroOptical Innovations > 55 Orchard Rd > Briarcliff Manor NY 10510 > 845-480-2058 > hobbs at electrooptical dot nethttp://electrooptical.net > > [ShotNoiseGen.asc1K ]Version 4 > SHEET 1 880 732 > WIRE 80 32 16 32 > WIRE 160 32 80 32 > WIRE 400 32 288 32 > WIRE 16 48 16 32 > WIRE 160 48 160 32 > WIRE 80 64 80 32 > WIRE 400 64 400 32 > WIRE 288 96 288 32 > WIRE 160 128 160 112 > WIRE 16 160 16 128 > WIRE 80 160 80 128 > WIRE 288 208 288 176 > WIRE 400 208 400 144 > WIRE 400 208 288 208 > FLAG 16 160 0 > FLAG 400 32 Output > FLAG 80 160 0 > FLAG 160 208 0 > FLAG 288 208 0 > SYMBOL res 384 48 R0 > SYMATTR InstName R1 > SYMATTR Value 10k > SYMBOL current 16 128 R180 > WINDOW 0 24 88 Left 0 > WINDOW 3 24 0 Left 0 > WINDOW 123 0 0 Left 0 > WINDOW 39 0 0 Left 0 > SYMATTR InstName I1 > SYMATTR Value {Iphoto} > SYMBOL voltage 160 112 R0 > WINDOW 123 0 0 Left 0 > WINDOW 39 24 118 Left 0 > SYMATTR SpiceLine Rser=0 > SYMATTR InstName V2 > SYMATTR Value 0 > SYMBOL cap 144 48 R0 > SYMATTR InstName C2 > SYMATTR Value 1G > SYMATTR SpiceLine Rser=1f Lser=1f Rpar=1T > SYMBOL bi2 288 176 M180 > WINDOW 0 24 88 Left 0 > WINDOW 3 24 0 Left 0 > SYMATTR InstName B2 > SYMATTR Value I=Iphoto+I(V2) > SYMBOL diode 64 64 R0 > SYMATTR InstName D1 > SYMATTR Value Dshot > TEXT -216 128 Left 0 !.param Iphoto=1m > TEXT -216 160 Left 0 !.noise V(Output) I1 dec 10 1 1g > TEXT -200 104 Left 0 !.model Dshot D()- Hide quoted text - > > - Show quoted text - Phil, this is most likely a stupid idea, but does model have the correct source impedance for the 'diode as shot noise source'. R = kT/ (eI) (I loved the 'link' that I clicked on an it loaded the whole schematic.. cute) George H.
From: Phil Hobbs on 28 Oct 2009 13:51
George Herold wrote: > On Oct 28, 12:40 pm, Phil Hobbs > <pcdhSpamMeSensel...(a)electrooptical.net> wrote: >> Yuri Belenky wrote: >>> Phil Hobbs wrote: >>>> Dear all: >>>> I'm on a bit of a roll with TIA designs at the moment, but I've just >>>> been using current sources with caps in parallel to model >>>> fully-depleted photodiodes, and I need a better model to hack up. >>>> The LTSPICE Yahoo group's files area is broken at the moment. Do any >>>> of you have a decent PD model with 4 terminals (anode, cathode, and >>>> two to represent the light input)? >>>> Nonlinear capacitance would be a plus but isn't required. >>>> (I've used SPICE more in the last two weeks than in my entire previous >>>> career--I'm more of an algebra guy when it comes to circuit design, >>>> but some things really need sims.) >>>> Thanks >>>> Phil Hobbs >>> I've used this model several years ago (MRD500 photodiode): >>> --- model starts here ------------------------ >>> * PSpice Model Editor - Version 10.5.0 >>> *$ >>> ***************************************************************************�**** >>> * A = Anode >>> * C = Cathode >>> * P = (light)Power as voltage input >>> ..SUBCKT MRD500 A C P PARAMS: Spec=1.0 Sensy=0.3894 >>> * MRD500 from Motorola * RAP 7/97 >>> DPD A C PhotoDet >>> RDUMMY P 0 1G >>> GPD C A TABLE {V(P)* Spec * Sensy} (0,0) (1,1) >>> ..MODEL PhotoDet D IS=1.02p RS=10 N=0.841978 BV=100 IBV=1u >>> + CJO=6.03p VJ=0.202968 M=0.146605 TT=1n ISR=17p >>> ..ends >>> *$ >>> --- end of model ------------------------------ >>> Let me know if you need it as OrCAD library file. >>> Yuri. >> Thanks. >> >> A couple of people have sent models (Thanks, guys), but there is one >> remaining puzzle: shot noise. I'd have thought that the .asc file below >> would generate exactly the shot noise of Iphoto--diodes have full shot >> noise, so connecting it to a DC current source should turn D1 into a >> full shot noise current source, which ought to get picked off via the >> infinite capacitor into the 0V source, and so into the behavioural >> current source at the output. >> >> However, it doesn't do anything of the sort--it's all over the map. >> Different diodes and diode-connected transistors give all sorts of >> different values. >> >> Any ideas what's going on? One possible clue is that any resistance at >> all in series with V2 reduces the noise enormously. >> >><snip> > > Phil, this is most likely a stupid idea, but does model have the > correct source impedance for the 'diode as shot noise source'. R = kT/ > (eI) Hmm. That's an interesting point...perhaps the diode models aren't implemented the way I thought, with the shot noise being a current source internally. > > (I loved the 'link' that I clicked on an it loaded the whole > schematic.. cute) LTSpice rides again--flat ASCII schematic files. Go, Mike! Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net |