Spice models

[edvard]

In looking around for spice models for a few jfets that were not included in LTSpice, I had a thought...

Why is there no easy way to convert numbers from a datasheet to spice parameters? I'd like to be able to verify for myself models I find on the internet, as well as 'tune' things to my own observations.
Or is there a way, and I just can't find it?
Anybody know of any tutorials or guides?

On this page I found some JFET parameters referenced as "Key Parameters".
Does that mean that Beta, Vto, Cgs and Cgd are really the only "important" numbers for general JFET simulation?
What about transistors? Diodes? Etc?
(some listed at the same site, different page, http://edocs.soco.agilent.com/display/ads2008U1/Vendor+Component+Libraries+-+Analog+Parts+Library)

I'm not the world's greatest math whiz, so numbers fill my cognition buffer pretty fast, but I NEED to know things, in spite of my limited capability to understand them.
Thanks for your help.

PS I've searched this forum pretty thoroughly before posting, so If I missed anything, it wasn't for lack of trying

[edvard]

Oh man, I just found this guy who has a method for working out BJT parameters from a data sheet using Excel:
http://www.analogservices.com/excel.htm


That's it. I quit.

[Joe]

Download the models from semiconductor manufacturers, like Fairchild or OnSemi. The models are complex because they have to model temperature effects, etc.