gEDA-user: simulating power mosfets

[Phil Frost <indigo@xxxxxxxxxxx>]

I'm trying to simulate my first nontrivial circuit with ngspice. The
circuit in question is a discrete MOSFET driver. I wasn't able to find
any spice models for the power MOSFETs I'm using (Ixys IXTP200N055T2),
but I was able to find something from Fairchild for a similar device,
FDP032N08.

The trouble (besides not being experienced with spice) I'm having is
that the model from Fairchild is actually a subcircuit, and I'm not
entirely sure how to structure my schematic such that gnetlist will make
the right output. I'm running it as "gnetlist -g spice-sdb hbridge.sch"

Best I can tell, as long as the refdes attribute starts with "Q" then it
will be netlisted as Qfoo, which means spice won't be expecting a
subcircuit. I think (although I'm having a hard time finding the right
manual to read) that the identifier in the spice input must start with X
to reference a subcircuit. I thought maybe I could change the refdes to
start with X in the schematic (although I'd rather keep it as Q), but
then the netlister outputs "QXfoo". I'm thinking this is because my
symbol has an attribute device=NMOS_TRANSISTOR.

So, I'm left with a couple broad questions:

- Is there some combination of attributes I should set on my symbol so
  that the netlister will use the subcircuit?

- Is there a simpler way I should go about this? For now I'm mostly
  interested in what my driver can do to the gate of the MOSFET, and for
now less about what the MOSFETs do to their load (a DC motor).


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