# Photodiode.Transistors.

#### Weiseste

May 22, 2020
6
Hello,

I am a beginner, in simulation electrical and electronics circuits SPICE . I want to simulate a schematic with the program Micro-CAP 12.I want to look for some graphics from a photodiode PIN which is a InGaAs Photodiode IG22-Series,I want to monitor follow parameters:

• responsivity (A/W) vs wavelength(nm);
• dark current (A) vs reverse voltage (V);
• shunt resistance vs. temperature;
• detectivity vs. shunt x area;
• capacitance vs. reverse voltage;
• responsivity temperature coefficient.

And at the transistor BFP420 I want to monitor some graphics at the following parameters:

• total power dissipation Ptot = ƒ(TS);
• permissible pulse load RthJS = ƒ(tp);
• permissible pulse loadPtotmax/PtotDC = ƒ(tp);
• collector-base capacitance Ccb= ƒ(VCB)f = 1MHz;
• transition frequency fT= ƒ(IC) f = 2 GHz VCE = parameter in V;
• power gain Gma, Gms, |S21|² = ƒ (f) VCE = 2 V, IC = 20 mA;
• power gain Gma, Gms = ƒ (IC) VCE = 2V f = parameter in GHz;
• collector-base capacitance Ccb = f (VCB) VBE = 0, f = 1MHz;
• noise figure F = f (IC) VCE = 2 V, ZS = ZSopt;
• noise figure F = f (IC) VCE = 2 V, f = 1.8 GHz;

I do not know how to begin. Please help me. I accept, if is necessary any simulator of circuits.Or only important electrical parameters.I will attach a picture below.

Thank you for understanding,

Dragos.

#### Attachments

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#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,763
• responsivity (A/W) vs wavelength(nm);
• dark current (A) vs reverse voltage (V);
• shunt resistance vs. temperature;
• detectivity vs. shunt x area;
• capacitance vs. reverse voltage;
• responsivity temperature coefficient.
Of these afaik only sark current vs. reverse voltage is easily simulated by simply applying a reverse voltage and "measuring" the current.
Capacitance vs. reverse voltage can be found by applying a DC reverse voltage with an overlaid very small AC component. From the resulting AC current vs. AC voltaeg the capacitance can be calculated.
Temperature related parameters can be simulated, if the model of the component supports it, by changing the temperature as a parameter of the simulation (see manual if your simulator) and evaluating the parameter you are looking for as a function of temperature. A ".step" command is usually employed in SPICE based simulators.
Responsivity and detectivity can imho not be simulated as the simulator has no input for wavelength specific behavior of componnets.

May I ask why you want to simulate these parameters? The simulator will give you results based on the quality of the model for the component it uses for simulation. This model in turn is derived from datasheet parameters so you may as well, with less effort and better quality, look up these parameters in the datasheet.

• total power dissipation Ptot = ƒ(TS);
• permissible pulse load RthJS = ƒ(tp);
• permissible pulse loadPtotmax/PtotDC = ƒ(tp);
• collector-base capacitance Ccb= ƒ(VCB)f = 1MHz;
• transition frequency fT= ƒ(IC) f = 2 GHz VCE = parameter in V;
• power gain Gma, Gms, |S21|² = ƒ (f) VCE = 2 V, IC = 20 mA;
• power gain Gma, Gms = ƒ (IC) VCE = 2V f = parameter in GHz;
• collector-base capacitance Ccb = f (VCB) VBE = 0, f = 1MHz;
• noise figure F = f (IC) VCE = 2 V, ZS = ZSopt;
• noise figure F = f (IC) VCE = 2 V, f = 1.8 GHz;
Permissible values are limits defined by the manufacturer for proper operation of the component. These cannot be simulated.
You may be interested in this description on parameter extraction for bipolar transistors.
But again, getting these parameters from a simulation is not how it is commonly done (and doesn't make sense to me, just my 2 cents). On the contrary, real devices are measured and characterized to get the parameters for an approriate simulation model.

Study the manual (link) for details.

#### Weiseste

May 22, 2020
6
Thank you for this feedback.Yes.I understand it.I am agree with you.But with the helping with simulation the cost is less.In the point of financially of resouces.

For this, if it is possible to help me anybody, with greater experince.I will be grateful.

Please,can you help me.Maybe at the first steps?

Last edited by a moderator:

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,763
But with the helping with simulation the cost is less.In the point of financially of resouces.

Please,can you help me.Maybe at the first steps?
Look up the test circuits in the datasheet. Typically a datasheet shows how a component is tested or characterized.
Then "build" the test circuit in your simulator and run the simulation with the parameters varied according to the chart you want to generate.
If no test circuit is shown, create your own. But be aware that a test circuit that is not equal to the one used by the manufacturer can give different results.

#### Weiseste

May 22, 2020
6
Look up the test circuits in the datasheet. Typically a datasheet shows how a component is tested or characterized.
Then "build" the test circuit in your simulator and run the simulation with the parameters varied according to the chart you want to generate.
If no test circuit is shown, create your own. But be aware that a test circuit that is not equal to the one used by the manufacturer can give different results.

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