standard cell library download

Check here for descriptions of the vsclib and vxlib standard cell libraries.

The vsc library can be downloaded in Excel spreadsheet format. You can't actually make a chip from this, but there are a number of advantages.

no special software, not even M$ Excel is needed to view the cells. They can be viewed with Excel, OpenOffice.org Calc and Gnumeric on Linux, Windows and MAC platforms.
You don't need to learn new software in order to create the cells. I even found that the data entry time for copying from a hand drawing was quite comparable to other editors like Graal or Magic.
The printarea of each cell has been set to the abutment box size. Printing to postscript produces a vector postscript file which none of the open source IC layout editors will produce. They all produce bitmap postscript files. A vector image is a higher quality image and can always be converted to a bitmap image, but the reverse process is difficult. You can see the difference in the viewable GIF files for the vsclib and vxlib. The vsclib GIF files have been made from the postscript files printed from Excel using Adobe Illustrator and the “save as web” command. The vxlib GIF files have been made from postscript files printed from the Alliance AP files (created by the Graal program), and then converted to GIF by Illustrator. I think the GIF files coming from Excel are much more readable.
There is a strong programmable interface available in Excel, so it could be possible to output conventtional layout files. I haven't done it and don't plan to in the near future, but I would be interested to know if anyone tries this.

The disadvantages of course are the lack of any output like CIF, the inability to do any DRC or LVS checks, nor any Spice simulation. All the cells in the spreadsheets have been entered into Graal and can be downloaded from the vsclib alliance AP link above. A visual check has been made between the two drawings (and some corrections made!).

Both the vsclib and vxlib can be downloaded in Alliance AP format. This is created by the Graal editor and is a technology independent format. With the appropriate RDS file, CIF, GDS and Spice decks can be output in different technologies. RDS files to convert the layout to a generic 0.13um technology can be found here. The resulting CIF files can be downloaded from the links above. These CIF files are as produced from Graal with the S2R program. This only produces CIF with rectangle geometries which then overlap each other. In my opinion, a library release should be done with non-overlapping polygon geometries, but to date, I haven't been able to find an open source IC layout editor that can merge the rectangles into non-overlapping polygons.

CIF format does not define a connector syntax. The workaround has been to use user defined extensions. The normal one is to start a line with a connector definition with “94”. The Alliance CIF uses a different convention, starting a connector definition line with “4X”. I think this is a VLSI Technology/Compass Design Automation convention, and isn't understood elsewhere. I have written a simple script to convert to the “94” syntax and successfully read this into Magic. The links for the Magic files and CIF used to create them are above.

I have used the old MOSIS CIF layer definitions. These are not the same as the original Alliance ones. In order to read the CIF files in Alliance Dreal you will need the RDS files from this site.

Magic is also a design rule independent IC layout editor. Layout is drawn using 2um layout rules, and then scaled to the desired micron rules when writing CIF or GDS. To ease the CIF read in process, I wrote a 2um CIF file using S2R, changed the connectors definitions from “4X” to “94” and imported into Magic to create the MAG files.