Diode and Transistor Parameters?

Does anyone understand how to take manufacturer's data for their discrete semiconductors and figure out what to put them into the program parameters? They just don't seem to match up that well.

by joeyglloyd
December 07, 2013

If only it were that simple ...

About datasheet, device and simulation model parameters

To edit models see:



You cannot simply map datasheet parameters onto a device simulation model.

However, if you can find a spice model for your target device, then you can edit the relevant parameters of one of the built-in CL models and use that in your circuit.

For more information please see this thread:


Note that there are some unanswered questions about editing CL model parameters (which may not affect you anyway):


This thread has several links to more about spice diode parameters:


SPICE parameters for devices have little to do with datasheet specifications. They are much more to do with semiconductor physics and the particular process under which a given device is manufactured at the foundry. Consequently it is not always a simple task to map datasheet information onto the model parameters.

If you want to try to understand more about what the SPICE - and hence CL - parameters mean in diodes, bipolar transistors and MOSFETs, then you might like to have a look at:


with individual slide sets:




For more detailed information about bjt's in particular, have a look at this book:


available from:




Another excellent (and free) book about transistor modelling, go to:


and register to get a copy of:

Definitive Handbook of Transistor Modeling

by signality
December 08, 2013

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