Abstract Generator
When homemade layout is to be used in the place-and-route tool Silicon
Ensemble, or the new
SOC Encounter, an Abstract view is required. This should be
in the form of a lef-file, which
can be read by the SE or SOC tools.
The lef-file is generated by the Cadence Abstract Generator (AG).
For the moment, the files needed to generate abstracts is only built by the
two setup-scripts
'~amslibs/v3.51/ams_setup54' or from the efd-domain 'inittde dig2004'.
Quick User Guide
There are two types of abstract views that can be created.
Core : Intended to be placed together with the standard cells
and has to be of the same height
and general outline as the
one supplied from AMS.
Block : Usually bigger functional structures that are placed separate
from the standard cells.
First a layout view has to be created. Make the pins in the METn:pn layer
and make sure
that the text label ends up on top of the wire to be named. Make sure that
no other metal is
in the same area. Do not crowd things together, there should be space enough
for via con-
tacts to be placed on the pins.
The AG needs a stream-file as input so it has to be generated
which is done by the command
'CIW: File > Export > Stream'. Fill in the name and library
of the cell and chose the output
file name to be '<cellname>.gds'.
Then the generator can be called on to do its thing. It can be run interactively
but there is a
command script that should do all the work necessary.
$AMS_DIR/BuildAbstract -s Block cell.gds
# or '-s Core' for
core cells.
This will create a file with the name 'cell.lef'. This file contains
some rubbish which has to be
removed before it is used. The command
sed -n '/MACRO sflop/,/END LIBRARY/p' < cell.lef > cellX.lef
will do the trick. For a final touch, add 'NAMESCASESENSITIVE ON ;'
as the first line of the
new lef-file, cellX.lef.
The final lef-file can now be used in Silicon Ensemble as usual.