Re: Inconsistencies with Electric v6.07??? ....

[Todd Hochwitz]

Steven:

Thanks for the quick and informative response!

I'll mull over your info about the library and option saving.  Since I was
able to get the MOCMOS rules into the MOCMOSSUB technology without any
problems, I think I can get the present library to work for the students.

>There is no connection between the facets in the library and the
simulation 
>engine that is used.  I have no explanation for the phenomena that you are 
>reporting.  If you want to send an example of this, I will look into it 
>further.  You should send a SMALL library and instructions for repeating 
>the problem.

OK.  I tried the test again this morning, and was able to replicate the
behavior once, failed to replicate once.  So there must be something about
the order in which I'm doing things -- I'll try to track this down again,
but for now it isn't completely reproducible.

>Once again, the "current technology" is important here.

Ah ha!  Got it.  I was operating under the faulty assumption that the
technology information was also saved with each part on the facet.  I did
as you suggested -- make sure that I have the MOCMOS as the current
technology, and all the SPICE parasitics were indeed extracted from the
circuit, even with SPICE parts present.  Chaneg the technology, but keep
the same facet open, and the SPICE extraction doesn't generate parasitics. 
Thanks for the pointer on that one.

>It isn't the SPICE parts that is changing the value of lambda, it is your 
>use of a load transistor.  You picked a "schematics" transistor.  You 
>should have placed a "bicmos" transistor.

Well ... that is what I was afraid of at first.  Which is why I examined
the technology units immediately after selecting the SPICE part, but before
placing it on the facet.  And I tried the following experiment twice this
morning (on two different machines):

* I started Electric v6.07, and examined the default technology units (did
not load in my own library).  The ones of interest to me are:

BiCMOS   2000, 1u
MOCMOS  400, 0.2u
MOCMOSSUB  400, 0.2u

* I changed the technology units to the 0.8 lambda for the process we'll be
using:

BiCMOS  1600, 0.8u
MOCMOS  1600, 0.8u
MOCMOSSUB  1600, 0.8u

(yes, I know -- we're not in the sub micron range.  humor me *grin*)

* I closed the dialog, and opened it again.  The technology units were now:

BiCMOS  1600, 0.8u
MOCMOS  1600, 0.8u
MOCMOSSUB  1600, 0.8u

* So I changed the current technology to schematic, analog, and looked at
the technology units:

BiCMOS  1600, 0.8u
MOCMOS  1600, 0.8u
MOCMOSSUB  1600, 0.8u

* I next selected the SPICE part (but did not place it) -- clicked on the
SPICE icon, selected DC Voltage Source

* I saw a progress bar as Electric read something from disk, and when I
examine the technology units:

BiCMOS   2000, 1u
MOCMOS  400, 0.2u
MOCMOSSUB  400, 0.2u

* I hadn't placed any SPICE parts -- just clicked on the SPICE icon

* Looking at the "spiceparts.txt" file from the source distribution, I see
the following:

Line 24 has "techname: mocmos lambda:400"
Line 26 has "techname: mocmossub lambda:400"
Line 27 has "techname: bicmos lambda:2000"

* OK ... so I quit Electric, open up a text editor, and change the lambda
of 400 to 800 and lambda of 2000 to 1000 and repeat my steps above

* Now, just after clicking the SPICE icon (but I don't place any parts) the
technology units are listed as:

BiCMOS   1000, 0.5u
MOCMOS  800, 0.4u
MOCMOSSUB  800, 0.4u

Perhaps I'm misreading the technology units window.  Do the values in the
window reflect the present settings for the library, or do they reflect the
most recently assigned value (which appears to correspond to the SPICE
parts file, and not what I set them to)?

>Another workaround is to change the value of lambda in the 
>schematics technology so that it matches that of your layout technology.

Hmmm ... looking at the list from the Change Units window, I don't see the
schematic technology.  But I know that I had re-set it to a value of 1600,
0.8u.  So I looked at the various .txt files in the lib directory, and I
see that I changed all of the .txt files when I had removed the BiCMOS,
MOCMOS, and MOCMOSSUB settings.  Is there another place to change the
schematic units from within Electric?  I seem to recall being able to do it
in v6.04.  Sorry to be so obtuse.  *grin*

>Good luck with your course.

Thanks.  I'm not a "digital" person, so it shall be interesting.

Todd Hochwitz

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