IPL and the Virtuoso arm-lock


If you had something like an 80 per cent market share and one of the factors in that was a proprietary language, would you open up the language knowing that this would help competitors turn a foothold into a stronger position? No, I probably wouldn’t either.

But there comes a point where the proprietary language becomes a problem to the customers because it makes it harder to use stuff that has been developed outside that environment. And the customers have to choose between migrating or sticking with what they know and reinventing stuff that they know exists elsewhere. If those customers migrate, then the dominant company loses the reason for holding on to that language - it becomes more of a millstone than an advantage.

In the case of custom and analogue design, the language in question is Cadence Design Systems’ Skill. It’s grown like topsy over the years to the point that even people who’ve worked at Cadence aren’t quite sure what’s in it. Those outside the company don’t stand a chance. But a scripting language like Skill is crucial not only to general custom layout, as it prevents analogue engineers from quietly going mad repeatedly drawing the same shapes over and over again. It also forms the basis of things like process design kits (PDKs) that the foundries provide, as it allows them to define how cells and components are laid out.

If you only support Virtuoso as a foundry, then the work isn’t too bad. But life suddenly gets more complex if you want to support some of the other custom layout environments, such as SpringSoft’s Laker or Synopsys’ own foray into layout editing, which can only go so far in being a Virtuoso workalike.

So, the initial release of the Interoperable PDK Libraries (IPL) Alliance standard helps everyone who isn’t Cadence - it provides a format that foundries such as TSMC can get behind to ensure that they can work with tool suites that don’t come from Cadence. Tom Quan, deputy director of design methodology at TSMC said the standard will help cut the cost of PDK development at the foundry.

Both Virtuoso and the IPL standards are designed to work with the OpenAccess database format developed by Cadence and now maintained as an open standard by the Silicon Integration Initiative (SI2). The alliance’s plan is to donate IPL to SI2, said Oz Levia, vice president of marketing and business development at SpringSoft, one of the members of the IPL Alliance. But things like iPDK can go further than simply scratching the collective itch of people who want to eat into Cadence’s market.

“Custom design gets easier as more standards participate in the game,” said Levia.

If it was only the foundries and EDA companies with an interest in iPDK, then Cadence could rest easy. Instead of Skill, although IPL could support that if Cadence opened it up and provided a language reference manual, IPL supports a variety of scripting languages for automation. The main one in use is Python. This makes the scripts far more portable across tools than is the case with Skill code. Companies using the PDKs can more easily build their own routines on top and expect them to work in different tools.

“I hope that this will open up a competitive market for more players to innovate and offer their technology. I think it will grow because there will be more automation. Before this, you had to get around the proprietary lock on the Skill code,” Levia added, referring to the language used by Virtuoso to automate aspects of layout creation, such as drawing inductors and other on-chip components.

Levia claimed a number of medium-sized integrated device manufacturers and large fabless companies are planning to use IPL, “especially the fabless companies that are large enough to have clout with foundries to have custom libraries. They are doing their own PDKs based around IPL”.

“I think Skill is a huge problem. I know that Cadence is using Skill as a way to force the Cadence customer community to stay with a tool that is less competitive than other tools. I think it’s bad in the long run for customers and the industry,” said Levia.

“I would challenge them to open it up because I think it would be good for customers, the industry and for Cadence. I think it is stifling innovation and it’s stifling growth. There is no reason for it.”

IPL is not going to affect Cadence’s position overnight but it threatens to eat into Virtuoso’s share because some of its most active customers now have a vested interest in not using Skill.