Custom IC Design Flow with OpenAccess

Imagine being able to use any combination of EDA vendor tools for schematic capture, SPICE circuit simulation, layout editing, place & route, DRC, LVS and extraction. On the foundry side, how about creating just a single Process Development Kit (PDK), instead of vendor-specific kits. Well, this is the basic premise of a recent webinar from Brian Bradburn at Silvaco. The custom IC design flow with all Silvaco tools is shown below:

Foundries have long been creating vendor-specific Process Design Kits (PDK) for all of the major EDA vendors, which requires a lot of engineering effort. To streamline this engineering effort several standardization efforts have arisen.

PDK
A Process Design Kit (PDK) is just a collection of files and folders that define the front end and back end technology for IC design on a particular process node. Silvaco has created about 150 PDKs so far with a focus on low power, analog and power management foundries like:

• TSMC
• UMC
• TowerJazz
• X-Fab
• GLOBALFOUNDRIES
• ON Semiconductor
• VIS
• SMIC
• Dongbu

iPDK
Interoperable PDK (iPDK) came from TSMC starting in 2007, and by 2009 the first 65nm iPDK was ready. The iPDK Alliance called IPL controls the iPDK specification and members include: Altera (Intel), Ciranova, Mentor Graphics, Pulsic, SpringSoft, Synospys and TSM with Xilinx and STMicroelectronics as advisors. With iPDK the foundry and partners spend less time on PDK development.

OpenPDK
As with much in the EDA industry, there will be multiple standards so OpenPDK is yet another approach, this time from Si2.org, using an XML structured file and translators for main vendor tools. Each supplier creates their own parser to create the standardized exchange format. An OPDK can also create an iPDK.

OpenAccess
Cadence created a standard way for any EDA company to read/write their IC design data for front-end and back-end, calling this OpenAccess. With OpenAccess an EDA vendor uses API calls to get IC data, which enable design data portability.

So you can open up the same schematic in either Virtuoso from Cadence or Gateway from Silvaco. In the Silvaco front-end tools you can either use native data or quickly translate to or from OpenAccess, your choice.

Issues

All of this IC design reuse sounds really promising and liberating, however there are some issue for you to aware of. There can be subtle differences between Cadence PDK (using Skill), iPDK (Tcl), custom PDK (Tcl, Python, Perl).

OpenAccess is certainly a great idea, yet over time there are different versions like DM4 in use today while DM5 is under design. Each data model is not compatible between versions, so you must have the compatible version in your tool flow. Vendor translators to OpenAccess need to be maintained and kept up to date. Finally, Cadence uses Skill code, which is not released as Open Source, so you need a copy of Virtuoso to update their cells.

All Silvaco Tools
To give you an idea of how many EDA and Tcad tools that Silvaco has to offer, look at the following chart:

Q&A

Q: Is Silvacopart of IPL?
A: We don’t really need to join, because the existing members are pushing iPDK in the right direction.

Summary
The lofty goals of taking your existing EDA tools and using an interoperable PDK are now reality, which really allows engineering teams to choose their front-end and back-end tools based on the design size, complexity and project budget.

Webinar Archive
View the archived webinar online here, after a brief registration process.

Related Blogs

• IC Design and OpenAccess
• Variation Aware FinFETs are Critical!
• Academia and TCAD Grow Closer
• Learning About 3D Integration of ICs and Systems

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