gEDA-user: Problem with 2N3906 model in gnucap
gene
carzrgr8 at optonline.net
Wed Feb 6 05:44:49 EST 2008
al davis wrote:
> I assume you are aware that those model parameters need to be
> taken with a bit of suspicion. For example, the NPN gives
> a "Bf" value (forward beta) of 416.4. For real transistors
> this parameter varies widely. Any number from 200 to 500 would
> be believable, and they do vary this much in production. Other
> parameters vary like this too. I just picked this one because
> the beta of a transistor is well understood.
>
Beta also varies with collector current, do the simulators (and these
models) account for this behavior? In fact, the curves for different
transistors (beta vs. IC) are so incredibly different - some flat, some
very peaky before rolling off.
Just curious.
gene
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