Is it possible to model a photodiode PIN InGasAS,in MicroCAP 12 or LTspice? - Page 1
Forum section: electronics / projects

author: Weiseste
author_rank: Newbie
timestamp: June 25, 2020, 08:49:54 am
content: I want to know if it is possible to model a photodiode InGasAs panchromatic PIN , in accord with datasheet, in simulator SPICE MicroCAP 12 or LTspice.Because the supllier where I boughit it has not a SPICE model.And if it is possible, which are those steps. Here it is data-sheethttps://www.tme.eu/en/details/ig17x1000s4i/photodiodes/laser-components/And below I will attach a electric schematic, a transimpedance amplifier with phototdiode, used like receiver of smoke.I want to monitor graphically the impulse of photodiode in function of output of transimpedance for sensibilty. There is type of photodiode,which I found it in library Micro-CAP 12, it is simpe photodiode,which does not follow in accord in datasheet.There is photodiode macro.Thank you.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 25, 2020, 09:09:59 am
content: The photodiode macro model should be reasonably OK. One may have to adjust the capacitance. If used at different voltages one would also adjust the corresponding parameters - not sure which are the ones used. For just the circuit it should be OK to adjust at the voltage used, no need to care about the voltage dependence.The shunt resistance may be important when it comes to noise performance, but it should not effect the pulse response.

author: Ian.M
author_rank: Super Contributor
timestamp: June 25, 2020, 09:18:06 am
content: There's not enough data in the datasheet to model it directly, but if you took a sample one, totally obscured its window then measured its Vf vs If and Ir and Vr characteristics, you could curve fit a SPICE diode model (modified Shockley equation) to it. Its then just a matter of developing a control function for the arbitrary current source providing the photocurrent to match the fig.9 'Linearity' curve. Unfortunately trimming the whole model to match the fig.8 'Sample Pulse Response' is more problematic as junction capacitance and thus speed varies with bias, and only the zero bias response is given.

author: Weiseste
author_rank: Newbie
timestamp: June 25, 2020, 10:01:54 am
content: Here is the datasseet.https://www.tme.eu/Document/726cc5089c90f506f2d9a008ec28a891/ig17.pdf.Please any suggestions which help me to reach at any result, they will be great helpful me..

author: Weiseste
author_rank: Newbie
timestamp: June 25, 2020, 10:12:31 am
content: I treid, also, Do I follow the equivalent circuit, from this doecumt.Will I have any chance to get the respective results ?http://www.osioptoelectronics.com/application-notes/an-photodiode-parameters-characteristics.pdf

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 25, 2020, 12:51:50 pm
content: Hi,I have had a quick look at this.If I start with a very simple model for the photodiode, a current source in parallel with the junction capacitance.I get the following model:I am showing two test circuits, the OP amplifier and an ideal amplifier.The result is:The performance is dominated by the amplifier, not the PD.I would start by reducing the value of the emitter resistor on the first transistor.I have attached my LTspice model.I did not model the BFP420 transistors, because they have two emitter connections, they are including package parasitic inductance etc.Regards,Jay_Diddy_BTIA Model.asc(3.69 kB - downloaded 348 times.)

author: Marco
author_rank: Super Contributor
timestamp: June 25, 2020, 02:25:24 pm
content: Quote from: Jay_Diddy_B on June 25, 2020, 12:51:50 pmWhy? Small signal doesn't see the resistor. Reducing it increases the bias current, but BFP420 will have a fair bandwidth even at 60 microamps and the low bias current will also decrease the current noise going into the base ... which might be the intention?

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 25, 2020, 02:35:08 pm
content: Hi,I see this:So dropping Re improves the BW.Transient ResponseThis with the 2N2369 transistors, the BFP420 may be better?Jay_Diddy_B

author: Marco
author_rank: Super Contributor
timestamp: June 25, 2020, 11:33:30 pm
content: Yah, these high frequency transistors will have far better bandwidths at low bias currents. SiGe even moreso.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 26, 2020, 02:50:05 am
content: Hi,This is an LTspice model including the BPF420 models from Infineon. I had to make a symbol for an NPN BJT with two emitters. This is included in the zipfile.This is the result of stepping Q1 emitter resistor.The zipfile is attached.Regards,Jay_Diddy_Beevblog tia pd.zip(1.97 kB - downloaded 213 times.)

author: Weiseste
author_rank: Newbie
timestamp: June 26, 2020, 05:03:04 am
content: Thank you for feedback.What program do you use?And my question it is about if it possible to model a InGasAs panchromatic PIN photodiode, in accord with datasheet, in simulator SPICE MicroCAP 12 or in program LTspice.I want to monitor graphically the impulse of photodiode in function of output of transimpedance for sensibilty,the form it must be, an optical rectangular impulse, atthe input of photodiode, and that signal I wnat to monitor with the signal output ofg transimpedance amplifier.At the third pin of photodiode, a voltage source in impuls.And this is the results graphically.

author: Marco
author_rank: Super Contributor
timestamp: June 26, 2020, 10:35:24 am
content: The photodiode model seems fine, but the simulator seems to say your amplifier oscillates and has a weird delay (presumably it's saturating somewhere, reduce the input signal).

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 26, 2020, 01:36:32 pm
content: Hi,Using the information found here:https://www.lasercomponents.com/fileadmin/user_upload/home/Datasheets/lc/kataloge/ir_components.pdfAnd modeling:Quantum EfficiencyNon LinearityThese were modelled with polynomials obtained by curve fitting the datasheet.LTspice ModelVoltage source V1 is the optical power that falls on the photodiode. The scaling is 1V represents 1W.There are parameters for wavelength and Junction Capacitance.and I get the following result:The LTspice model is attached.Regards,Jay_Diddy_BPD Model.asc(3.48 kB - downloaded 278 times.)

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 26, 2020, 01:49:47 pm
content: Hi,These are the curves used:andRegards,Jay_Diddy_B

author: Weiseste
author_rank: Newbie
timestamp: June 26, 2020, 02:14:01 pm
content: Thank you for this feedback.Can you help me please to integreat that model of photodiode in th electrical schematic.I want to monitor graphically the impulse of photodiode in function of output of transimpedance for sensibilty,the form it must be, an optical rectangular impulse, at the input of photodiode, with a perioad of 20ns and , the interval of voltage must be between -20V and +20V, and the optical power must be between 100 and 100mW/cm^2.Thank you.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 26, 2020, 04:09:58 pm
content: Hi,The sensor has a diameter of 1mm.The area is Pi x d / 4 = 0.78 mm2.You have a power density of between 100W and 100mW per cm2So this is 1W to 1mW per mm2The datasheet shows the photodiode is non-linear above 8mW:It doesn't look like you have the right sensor. I suggest that you talk to the manufacturer.Regards,Jay_Diddy_B

author: Marco
author_rank: Super Contributor
timestamp: June 26, 2020, 05:08:12 pm
content: Or use an attenuator.

author: Weiiseste
author_rank: Newbie
timestamp: June 27, 2020, 04:21:46 pm
content: I am sorry. I wanted to say. between 100W and 10uW/m^2.Thank you.Dragos.

author: StillTrying
author_rank: Super Contributor
timestamp: June 28, 2020, 10:45:58 am
content: "between 100W and 10uW/m^2"LOLIf that's correct you'll have to lower that range quite a bit, these transistor circuits can only keep thepulse shapeover a range of about 100:1.I don't know what the phododiode's currents are or the pulse widths from this thread.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 28, 2020, 12:58:31 pm
content: Hi,Quote from: StillTrying on June 28, 2020, 10:45:58 amYes that is what I was thinking:10uW m-2On the area of the sensor 0.78mm20.78E-6 m-210E-5 x 0.78E-6 = 7.8E-11or 78 pAJay_Diddy_B

author: Weiiseste
author_rank: Newbie
timestamp: June 28, 2020, 01:52:35 pm
content: Or. How can it be better for this situation?

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 28, 2020, 02:09:48 pm
content: Quote from: Weiiseste on June 28, 2020, 01:52:35 pmAre you sure that the power level is 10MicroWatts per metre210E-6 m2?Moonlight is about 600uW m2(Full Moon)It is is tough to measure 78pA at DCIf you increase the area of the sensor you will get more current, but you get more capacitance.You also have to considerdark currentandnoise.Regards,Jay_Diddy_B

author: Weiiseste
author_rank: Newbie
timestamp: June 28, 2020, 03:23:00 pm
content: Okay. Which are your advice?. What considerations must I take?. To be better.

author: StillTrying
author_rank: Super Contributor
timestamp: June 28, 2020, 03:27:10 pm
content: Quote from: Weiiseste on June 28, 2020, 01:52:35 pmYou could give us some clue of the arrangement of the IR emitter and photodiode.The 1st post says"a transimpedance amplifier with photodiode, used like receiver of smoke.".If it's anything like these to detect the light scattered off smoke the photo currents will be at the very low end and the amp a high gain low bandwidth, probably an op amp.www.safelincs.co.uk/smoke-alarm-types-optical-alarms-overview/www.mavili.com.tr/en/smoke-detectors/1179-how-optical-smoke-detectors-work.html

author: Weiiseste
author_rank: Newbie
timestamp: June 28, 2020, 03:57:10 pm
content: Photo sensing circuits such as transimpedance amplifiers (TIAs) are useful in precision systems such as computed tomography (CT) scanners, blood analyzers, and smoke detectors.My circuit has the rooll to detect the smoke, for grenades.

author: Weiseste
author_rank: Newbie
timestamp: July 02, 2020, 07:27:46 am
content: Any answer?