[Magic-dev] ext2spice area and perim problems

[R. Timothy Edwards]

Dear Clint,

> Hello.  I am having a problem with ext2spice in magic 7.3.  Using both
> the command-line ext2spice and the built-in tcl command ":exttospice",
> I always get area and perimeter as zero for source and drain for all
> transistors in my spice file.  I have tried this with layout from two
> different technology files and it happens with both of them.
> 
> I tried using the magic 7.1 version of ext2spice and this does not
> happen.  Does anybody know what the problem might be?  Any help is
> greatly appreciated!

First try ext2spice with some obvious known circuit, like tut11a.mag,
with a known good techfile like scmos.tech.  I just did this;  I get
an assortment of transistors with zero and non-zero S/D areas and
perimeters.

Because magic calculates area and perimeter per node, nodes that are
shared between multiple transistor sources and drains have a calculated
*total* area and perimeter.  When writing SPICE, magic writes out this
total value for the first transistor encountered, and all remaining
connected transistors have their area and perimeter set to zero.
Using "ext2spice -d" will distribute the area and perimeter equally
between all transistors connected to the same node.

If you really have ALL S/D area and perimeter values set to zero, then
there is some fundamental error, probably with the technology file.  To
debug it I would need enough information to recreate the problem; that
is, the technology file you're using (or just the name of it if it is
a standard one), a sample layout that produces the problem, and a
verbatim list of command-line commands and options used.

					Regards,
					Tim

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| Dr. R. Timothy Edwards (Tim)   | email: tim.edwards at multigig.com     |
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