Defining The Next Standard Cell

Synopsys, Intel, IBM contribute technology for new parameterized cell to Si2.

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Synopsys, Intel and IBM all contributed technology to Si2 to create a standard version of parameterized cells, or PCells, for mixed-signal designs.

The move is an attempt to smooth out design incompatibilities using Synopsys and Cadence technology. Cadence is the clear market leader in this space. But as more technology is developed using different vendors’  tools for integration in complex chips, pressure has been increasing to build a bridge. That bridge technology, dubbed open PCells, is at the core of the OpenPDK Coalition’s work. This group is defining a set of open standards to allow an OpenPDK standard. This will allow an OpenPDK that could portable across multiple foundries and EDA tools.

“Open PCell is a working group under Si2’s Open PDK,” said Jingwen Yuan, president of IPL and strategic alliance manager at Synopsys. “The group is led by Si2, Intel and IBM. The goal is to standardize on Python PCells and to develop translators to go from a Python-based database to other Pcell languages.”

Parameterized Cells or PCells, like GDS II, are formats that have very long histories and are technologies that Cadence acquired many years ago. PCells enable analog layouts, or custom digital layouts, to be created and re-used. Rather than being statically defined, they are based on a number of parameters. Cadence sells the Virtuoso line of custom tools. PCell libraries are written using the Skill language, which is a Cadence proprietary language. This makes interoperability difficult, even with the existence of OpenAccess.

Synopsys sells a competitive tool, which is based on Ciranova’s libraries, called PyCell. At this point, PCell and PyCell are not compatible, which is a big issue both on the design side as well as the foundry side, where supporting multiple process design kits adds both time and cost to design. But PyCells work within OpenAccess, meaning the abstraction at which data can be moved around is much higher. To become really open, PyCells themselves have to become open and that is why this effort is being undertaken.

Si2 is working to create such a standard, and the technology donations are aimed at resolving these issues before they become a serious problem.

Among the latest donations:

  • Synopsys contributed a set of Python application programming interfaces (APIs) for creating PCells. The APIs add a high-level abstraction for layout.
  • IBM contributed a PCell template that will be used to test the design environment, including a regression suite for PCell variations.
  • Intel is prototyping a meta-language translator to allow Open PCell source to be used with multiple language outputs. The translator compiles OpenPCell source code in scripting languages such as Python, Tcl, Ruby and proprietary languages.

The effort is also part of Synopsys’ previous work in the arena. “This aligns with the iPDK standard because iPDK also standardizes on Python PCells,” Synopsys’ Yuan said. “And this is good for the expanding ecosystem of iPDKs sponsored by IPL. The donation from Synopsys is exactly the same donation to IPL Alliance a couple of years ago when Synopsys first acquired Ciranova. The contribution enables Si2 to build their standards (same as iPDK’s) and utilities on top of the well-established iPDK (Interoperable PDK) that is in wide usage today by foundries, end users and EDA suppliers. Synopsys is part of the OpenPDK Coalition and Open Pcell working group now.”

Si2 has scheduled a workshop on Open PCell later this month. The standards organization expects the standard to roll out later this year.

—Brian Bailey, Mark LaPedus and Ed Sperling contributed to this story.



  • Bill Bayer

    The Synopsys contribution of the PyCell technology is only one piece of many inputs the OpenPDK Coalition will use to to fuel their process of creating a unified standard to be released to the industry. There are three contributions to the PCell working group so far.The contributions will all be used to create that final standard. For a much more detailed explanation, watch for the new “Standards and Beyond” blog being published Monday morning on this web site, authored by Ted Paone, PCell Consultant to Si2.

    Bill Bayer, Si2
    Sr. Director