[SOLVED] SPICE WORKING Algo and info

[shabazsyed]

Spice uses model files to simulate mos designs. There are lot of mos model , meaning different levels. For different levels we have different equations. SO i think spice reads the level info from model file and reads parameters for that level from model file. I crossed verified this by changing level info in model file. So my question is does spice have all the formulas for commutation of current in source code? Please reply people . I got still unanswered threads. thanx

 

[erikl]

... For different levels we have different equations. SO i think spice reads the level info from model file and reads parameters for that level from model file.

Right. You can change the level number to a lower value, but usually not to a higher one, because higher levels mostly need additional parameters which may not be available in the model file.

... does spice have all the formulas ... in source code?

Yes. SPICE software knows all the equations which have to be solved for a certain level model. And it contains all the math necessary for the calculations.

 

[shabazsyed]

Thanks erikl. One more question....... Usually Foundaries provide model file for process. Which level model file do they provide. Is there any thumb rule which suggest which level to use for wat tech and How does spice update model files for nm processes.... Thanks again

 

[erikl]

There are so many model levels, s. View attachment hspice_mosfet_models_Sep_2005_p108-109.pdf .

If you want to rely on your simulation results, you surely have to use the model files from your fab/foundry. For sub-micron processes, usually BSIM3 or BSIM4 models are used, i.e. level 49 or 54.

Depending on what you want to simulate, there are sometimes specialized models available, e.g. the Synopsys LEVEL1 mosra model for NBTI analysis on PMOSFETs.

 

[shabazsyed]

That was great erikl , Thanx........... these spice n models are much more clearer to me now. Can u help me out here a little https://www.edaboard.com/threads/252119/... Thanx again...