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vlsidesign · Guest

Greetings,
How might one go about power plots using Mentor Calibre tool? Is there
a new rule dec needed or is it just a slight modification of the lvs
rule dec? I wanted to have one plot of the metal connections of AVSS,
one for AVDD, one for DVDD, etc.

Thanks.
Gary

Gerry Vandevalk · Guest

This is really a function of your technology ...

At my former employer, we would routinely create our own internal
power/ground plotting functions for each and every technology.

It does get a bit complex as the metal stack becomes >2 layers.

One way we "Simplified" the problem was to create a "functional plot" of the
base layers up to contact and then created
a separate "colour coded" (Canadian spelling here ;^) latchup plot that only
plotted zero biased diodes, ohmic diffusions and
conductors that were connected to a list of supplies. ( and any direct
connection to a pad!)

This exercise found many power-ground shorts over the years that were missed
by the factory checks!

after the "plottable" gds files were created we would then plot only sets of
layers on separate plots.

(i.e Base-Layers to contact ... M1-M3 ... M3-M5 ... M5-M7 ... as required )

We also wrote checks that flagged any supply that was "soft-connected" to a
higher layer as it was our experience that anytime
a supply net supplies power to a higher layer, it could be a sign of a lost
via structure in an area!

This was a function that several of us thought was essential, and time will
tell if they miss it dearly ...

Note that the creation of a power-ground or functional plotting deck is
essentially trivial.

It does however mean that you need to disconnect the substrate as a
conductor to plot the
multiple VSS/GND/VEE supplies.

Otherwise it just involves using the connect statements from the extract
deck and tossing out all of the devices.
(You do need labels and/or EDTEXT files )

Note that Calibre will create either error flags or Stream data output. Note
that the stream data output will be flat and
big and tricky to plot with a big chip ( i.e. I used hyperplot ... )

Good Luck at tweaking the deck.

-- Gerry Vandevalk www.ictooling.com

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