I am trying model a Phototransistor using ebers moll model but how do I find the model parameters.

 

The Ebers-Moll model is voltage-controlled using the base-emitter voltage. You don't have that. Nor do you have access to the base current in order to use a current-controlled model. What you want to use as your control signal is the illumination level on the junction. What you will likely need to do is use is some proxy for it, such as the current in an LED that is illuminating it and possibly modified to reflect what is actually being measured, such as the distance to the light source or absorption of light between the two or whatever makes sense for your application.

 

How do you plan on modeling the light source?

 

Spice models

 

Spice models

Those use the approach I was suggesting and have the same problem. There is no way to know what the right base current to use is. What you would need to do is take measurements in a circuit under different illumination conditions and build a current source that, when injected into the base, produces the same results as observed in the circuit. Perhaps they have data available elsewhere that provides information about effective base current as a function of illumination.

 

How do you plan on modeling the light source?

I am using the extended version of the ebers-Molls model and thought the model takes into account the light source and you wouldn't need to model the light source. but if not was planning on using the Kurokawa power wave

 

The extended version of the Ebers-Moll model is NOT the Ebers-Moll model (which is all you indicated in your original post).

There are several extended versions of the Ebers-Moll transistor model in order to take into account various things. Which one, exactly, are you using?

Your model and the circuit using it are going to have to have some means of getting information about the junction illumination into the model so that it can respond to it.

 

I am trying model a Phototransistor using ebers moll model but how do I find the model parameters.

Which phototransistor are you attempting to model?

 

Which phototransistor are you attempting to model?

I have few am trying to model which are;BPW85A, BPW96B, BPW77NA and BPW76A

 

I have few am trying to model which are;BPW85A, BPW96B, BPW77NA and BPW76A

Hi

Will you use the phototransistor as an IR sensor or ambient light sensor?
A few transistors are tailored more towards visible light.