Most parameterized cells (pcells) have been written in the Cadence Virtuoso environment, using the proprietary Skill scripting language found only in that environment. These pcells can only be used in a Virtuoso environment.
Ciranova, Inc., now owned by Synopsys, developed and championed the idea of portable pcells, pcells that would have published interfaces and use a common programming language, that could work in any design environment. The company provides a free downloadable ``PyCell Studio'' design kit. The concept is made possible by the use of OpenAccess, which has a well-defined framework for pcell support, is well documented, and source code is published. Cadence Virtuoso and most modern tools use OpenAccess.
Though OpenAccess provides support for pcell interfacing and management, actual execution of the pcell script is exported to external code supplied as a plug-in. The plug-in provides an interface to the language interpreter or compiler and other things required to execute the script. This plug-in is supplied by the system vendor or user. For example, in a Virtuoso installation, a Skill plug-in is provided. OpenAccess comes with example plug-ins for Tcl and C++.
Ciranova developed a Python plug-in for OpenAccess, with a set of interface functions for creating geometry and related purposes within OpenAccess. Python is a very popular, modern, open source scripting language. It is present on any standard Linux system, and is available for most other operating systems. Ciranova calls portable Python-based pcells that use the Ciranova plug-in ``PyCells''.
The PyCell Studio design kit contains tools for viewing, testing, and creating PyCells. An example library of PyCells is provided, complete with technology and display resource files. It also provides OpenAccess and Python, so the package is quite complete. There is comprehensive documentation and tutorials.
Though Ciranova has been bought by Synopsys, the PyCell Studio remains available and apparently is still under development. An industry group, IPLnow.com, which includes TSMC and other foundries and some tool vendors, is pushing the cause of ``interoperable'' PDK libraries based on portable pcells.
Whiteley Research fully supports this effort, and Xic will be interoperable with the PyCell Studio design kit and PyCells as much as possible.