gEDA-user: TwoStageAmp example

[Stuart Brorson]

> I grabbed the 2N3904.mod model from Stuart's tarball, tossed in th the
> models directory, reran the netlist, and now when I invoke ngspice, I
> get:
>
> Warning -- Level not specified on line "(is=1e-14 vaf=100   bf=300
> ikf=0.4 xtb=1.5 br=4   cjc=4e-12  cje=8e-12 rb=20 rc=0.1 re=0.1
> tr=250e-9  tf=350e-12 itf=1 vtf=2 xtf=3 vceo=40 icrating=200m
> mfg=philips)"
> Using level 1.

"Level" refers to the actual transistor model used.  For each type of
device, many different models exist of different levels of complexity
and accuracy.  If you don't call out a "level=" parameter in the
.model line, then SPICE uses the default model level=1, whcih is the
standard Gummel-Poon model IIRC.

Ngspice has different models/levels built into it for each device.
Peter Kaiser put together a list of supported levels and the
corresponding model.  You can find  it here:

http://www.easyasic.de/analog.html

> Error on line 9 : .model 2n3904 npn(is=1e-14 vaf=100   bf=300 ikf=0.4
> xtb=1.5 br=4   cjc=4e-12  cje=8e-12 rb=20 rc=0.1 re=0.1   tr=250e-9
> tf=350e-12 itf=1 vtf=2 xtf=3 vceo=40 icrating=200m mfg=philips)
>       unrecognized parameter (vceo) - ignored
>
>       unrecognized parameter (40) - ignored
>
>       unrecognized parameter (icrating) - ignored
>
>       unrecognized parameter (200m) - ignored
>
>       unrecognized parameter (mfg) - ignored
>
>       unrecognized parameter (philips) - ignored

Depending upon the model you use, different parameters may or may not
have meaning.  It seems that vceo, icrating, and mfg parameters are
meaningless for the level=1 model.

> Should I be worried?

Nope.

> Should I expect more out of the simulation than this?

Since ngspice is kinda bare-bones, what you're getting sounds
reasonable so far.

What happens when you run an analysis?  Do you get sensible results?

Stuart