Between The Lines

Swiss cheese makers wish they could inject as many holes in their product as the EDA industry has inadvertently managed to inject into the analog mixed signal and the custom digital tool flows. Now it's time for the EDA industry to finally step up and fill those holes. But to do it as quickly and smoothly as possible, Cadence Design Systems needs to open its SKILL Pcell description format and preferably donate it to Si'2 Open Access program, which Cadence more or less started years ago.

That's an opinion shared by most folks in the industry. It certainly seems to be an opinion shared by Cadence's (and in a way SKILL's) founding father (now venture capitalist) Jim Solomon, who delivered a very strong presentation on the issue at the Synopsys' Interoperablity breakfast this week at DAC.

Pcells are the analog equivalent of standard cells and SKILL is the language that describes them for use in tools. But to date, Cadence has yet to donate the language to Open Access and is thus restricting EDA vendors and customers from developing tools to enhance the aging AMS flow for today's larger and more complex ICs, which more often than not have analog circuitry.

"Today virtually every SoC is mixed signal," said Solomon in his presentation. "You've probably heard that 80 percent of every SoC is now mixed signal. If you include PLLs, virtually 100% of every SoC is mixed signal."

And these Analog and AMS designs are growing in size and complexity too, but designers today are using virtually the same analog tool flow that they were using 15 years ago, said Solomon.

Solomon said the traditional flow doesn't adequately address today's problems. Indeed Solomon said the analog, AMS tool flow needs a new schematic editor and cockpit, a Matlab-based simulator, a waveform display, an extension language, testbenches, circuit synthesis, a fastMOS digital SPICE, an optimizer, incremental DRC and RLC extraction tools.

But to finally get these tools into the flow in the easiest fashion, the EDA industry needs to have an open SKILL or it needs to go to plan-B and pick an alternative.

"What is needed is an open language," said Solomon in his presentation. "SKILL for example was a marvelous thing for many years. Now it looks ugly, is difficult to read, and has a poor development environment that isn't supported well. It has a lot of problems and it is not open….it was great 15 years ago and it's our baby, but I can't claim it is the right thing anymore because it isn't."

Solomon said Cadence should donate SKILL to Si2's OA effort, which could then enhance the language and development environment and offer it freely to OA members. SKILL is seemingly more attractive than alternatives such as tcl or (Python) PyCells because analog designers are familiar with it, and thus more likely to transition to tools running on it.

Certainly opening the language also opens Cadence up to more competition.When Cadence released LEF/DEF per an FTC mandate more than half a dozen years ago, it allowed Synopsys and Magma to emerge into competitors in digital IC physical design—it allowed Synopsys to take the lead for a quarter. But it also allowed Cadence to gain next generation place and route technology from SPC and Plato Design, integrate it quickly into a flow and ultimately regain first place in the industry. Cadence doesn't have an FTC mandate this time, but I'd like to think that an executive team that claims to feel the pain of designers because they were/are designers would make unrestricted tool interoperability its top priority. Perhaps they would go above and beyond any tool company in the past and be bold enough to finally fulfill EDA's promise to bring badly needed automation to the AMS flow, even if it means there could be a tuff fight ahead. You're up to it. All you have to do is hit "Send" (and probably some lawyer stuff too).

Share your views, please.