Hello everyone,


I have a question that I haven’t been able to resolve through LTSpice manuals or Linear Technology / Analog Devices documents.


When I use BJT models like Gummel-Poon, VBIC, or HiCUM, the simulator provides various parameters (IS, BF, BR, VAF, etc.), but I couldn’t find a reliable source that explains how each parameter is actually implemented in the model’s current and voltage equations. For example:

• How exactly does the IS parameter enter the base-emitter or base-collector current equation?
• How are Early effects (VAF, VAR) or temperature dependence modeled?
• Any references detailing the numerical implementation of these models in SPICE simulators, not just a parameter table.

I have searched LTSpice manuals and academic articles, but most only present the conceptual model or the parameter list without detailing the complete equations used in the simulation engine.


Would anyone be able to point me to:

1. Official technical documents explaining these equations in detail;
2. Academic papers describing how SPICE implements Gummel-Poon and more advanced models;
3. Or even an advanced electronics reference showing the model in complete mathematical form?

Thanks in advance!

 

May be these books will helpful:

"THE SPICE BOOK" by Andrei Vladimirescu

or "Compact Transistor Modeling for Circuit Design"
by H.C. de Graaf, F.M. Klaassen

 

You already have a thread on this topic:

https://forum.allaboutcircuits.com/threads/bjt-ltspice-gummel-poon-model.206154/

Please, one thread per topic.