Cadence Design System

Notes on Importing SPICE Netlists into DFII

These procedures were done in Cadence 4.4.3 (97A) on a large 4096x4 SRAM netlist.

Openbook Documentation: Design Data Translator's Reference, ch. 6, Translating CDL Files
Circuit Description Language (CDL) format is a subset of SPICE format, and seems to form the basis of all of the netlisting done from DFII to other formats (hspice, verilog, etc.). Differences from SPICE:

.global declares power, ground and clock
a slash (/) character in .subckt statements distinguishes input ports (following the slash) from output ports
a slash (/) character in element statements distinguishes a master cell name from the node names
empty cells (only titles and I/O names) are allowed for some applications
you don't actually have to implement any of these, but it does strictly enforce an 80 column line length at least on .subckt lines, so make sure those are rolled over with a CR/LF and a '+' (standard SPICE format)
all cells, including the top level, must be inside a subcircuit

CDL File - name of your spice deck
Hierarchy - full to maintain the spice deck hierarchy
Library Name - name of the library to put the netlist into
View Name - defaults to netlist; if you use this, you will probably have to add the netlist view to the switch view lists in some places, like Analog Artist
View Type - set to schematic
Schema Library - set this to the library with the primitive cells

the sample library contains some cells that will work
FETs will be converted into cells named nfet or pfet; it doesn't seem possible to change this; the translator does a good job of looking at the model name on and determining whether it is a n or p-channel device - NM and PM worked
suggested method if your library does not use nfet and pfet devices

copy the MOSFET cells from your technology library into a working library
rename them to nfet and pfet
after the netlist has been imported, rename these cells to what they are in the technology library and update the references
change the reference library to point back to the technology library

After the netlist have been imported you can look at the cellviews, but the components are stacked on top of each other and you can't edit anything other than properties
There may be issues with subckt parameters being imported as design variables, which need setting in Analog Artist, but I didn't investigate it

Brett Warneke, June 23, 2000