A parameterized cell, or pcell, is a graphic, programmable cell that lets you create a customized instance each time you place it.
There are several advantages to using parameterized cells (pcells). First, they speed up layout by eliminating the need to create duplicate versions of the same part. Second, they save disk space by using a single layout to represent an entire family of parts. Third, they eliminate errors that may occur because multiple version of the same part are being used.
The most powerful way to create pcells is to write SKILL language files that describe how the part is to be drawn. Cadence then keeps that programme in the design library and uses it to create the customized parts on demand. The cells are distributed as a number of files with the extension ".il", which indicates a SKILL language file.
These cells are freely available for academic use. If you find that these cells help you in any work that you publish, we would appreciate an acknowledgment. For non-academic use, please contact me.
Cronos also has a publicly available library of MUMPS cells. Their library is called CaMEL. The library contains some parameterized cells not available here, plus a library of non-parameterized cells.
Step 1: Physical Rules
Pcells need access to the design rules. This access allows the pcells to ensure that the design will pass DRC and is manufacturable. For example, pcells may constrain certain parameters to valid values. Additionally, some device dimensions may not have corresponding parameters.
Fortunately, as part of the technology file associated with every design library, Cadence maintains a database of design rules.
These rules can be edited by accessing the
File menu in the
CIW (also known as the
ICFB). While these rules can be entered manually, it is much easier to import an ascii technology file that contains the definitions.
An ascii technology
file containing all of the physical rules used by the pcells available at this site can be downloaded here.
Download the file
From the ICFB, open the
|Step 3:||Type in the filename to the saved technology file for the first field, "ASCII Technology File".|
|Step 4:||Although the file contains only physicalRules, to be safe make sure that the only box checked is the one for physicalRules.|
|Step 5:||Select the library into which you want the physical rules to be saved|
|Step 6:||If you wish to replace any existing physical rules, select Replace, otherwise select Merge.|
|Step 8:||When exiting Cadence, you may be prompted to save changes to the binary technology file associated with the library. The changes must be saved to have the physical rules present the next time you run Cadence.|
Step 2: Support Routines
It is likely that any of the cells you install will make use of some support routines. These source files containing these routines are listed below. Unlike the code for the pcells, Cadence does not keep a copy of these routines in the design library and so these source files need to be loaded every time Cadence is run. Fortunately, there is an easy method to ensure this happens automatically.
Download the following files into the directory of your design library. The complete path to any design library can be found
by selecting the
The following lines need to be added to the file
If you plan to install or use any pcell without restarting Cadence, you should also enter all of the command listed in
* This routine needs to be copied only if you are planning to install the lever cell.
Step 3: Install Cells
Unless otherwise specified, all of the pcells will try to install themselves into the library named
ADM. To override this, please enter the following line into the
admLibraryName = "your libraray name"
Before loading the file, as described above, you may also want to change name of the cell. This is trickier, and must be done by editing the skill file.
To install any pcell into your Cadence library, download the SKILL file for the pcell. All of the SKILL files should have
an extension of ".il". Once the file has finished downloading, type
the following command in the
Once the file has been loaded, the pcell should be available every time you run Cadence as the code is saved as part of the design library.
If you have a large number of pcells to install, the file install_pcells.il may
be useful. It will load all of the pcells in a given directory. To use it, first override the library name, as
described above. Additionally, you can override the skill file path. The skill file path defaults to
./ADM/. However, if you have saved the skill files in another location, use the following line
to set the skill file path:
admLibraryPath = "skill path"
Please note that the skill path must contain the trailing slash.
To install of the pcells in the specified path, load the
install_pcells.il skill file. It will go
through the contents of the directory and install all of the pcells found there.
 Virtuoso Parameterized Cell Reference. pp. 1-5.