| SANTA CLARA, Calif. — The Fabless Semiconductor Association (FSA)'s standardized mixed-signal/RF Spice model checklist has been finalized and published. All of the major foundries have pledged to deliver the completed checklist with all Spice models by the end of the year. But what, or who, will ensure that foundries provide accurate information about their Spice models? |
This question was posed by an Atmel Corp. executive attending an FSA technical session Thursday (Aug. 11) and considered by FSA representatives and leaders of the working group that developed the checklist. The answer, in short, is that foundries completing the checklist are on the honor system.
The checklist, released Aug. 1, is designed to provide fabless mixed-signal/RF designers using foundry Spice models with consistent data to help them "compare apples to apples" and make foundry and design decisions. Its stated goal is to provide a basis for designers to compare and evaluate various Spice models, cutting though company-specific processes and terminology, in a standardized format — similar to nutritional facts labels found on food. Through reviewing the completed checklist, a designer is supposed to gain better understanding of the source data, measured devices, completeness and quality of a model before using it to design ICs.
Since one of the checklist's heralded benefits is creating a level playing field to help fabless companies decide which foundry to choose, it is conceivable that a foundry desperate to land a major piece of business might be tempted to exaggerate, embellish, or outright lie when completing it.
The FSA has provided meticulous documentation along with the checklist, including a separate users guide, which provides detailed information about completing and reviewing the checklist, and a comprehensive set of taxonomy and definitions, to make sure that foundries are using the same terms in a consistent manner. But, as of now, there is no mechanism for ensuring scrupulous compliance by the foundries. Is oversight necessary? Do the foundries need to be policed?
Lisa Tafoya, FSA vice president of global research, believes there is no real need for formal oversight.
"I think [the checklist] will enable self-policing," Tafoya said. "I don't think a foundry is well served by exaggerating the effects of what they are doing, because the customer will see that. If a foundry develops a reputation for exaggerating the performance of its models, it makes it easier for a customer to move on to the next foundry."
James Victory, RF modeling and characterization manager at pure-play foundry Jazz Semiconductor (Newport Beach, Calif.), agreed that the potential damage to a foundry's reputation would vastly overshadow the short-term gain of a customer win. "It's a really small industry," he said.
But Tafoya also would not rule out the possibility of the FSA acting as a compliance enforcer and certifying checklist results if it proved to be something that members clamored for.
"We are happy to act in that role to encourage foundries to live up to expectations," Tafoya said. "The FSA is happy to take that on as an endeavor. But that being said, I don't know if our role is to be a gatekeeper" to ensure scrupulous completion of the checklist.
Ken Brock, chairman of the FSA's mixed-signal/RF model working group and vice president of marketing at Silvaco, said the working group considered the matter, but was unable to come up with an iron clad solution. "We struggled with that one," Brock said.
But Brock said he and other members of the working group fought to keep process specifications and other items that might appear in a foundry marketing brochure off the checklist so that it would represent strictly facts, rather than hyperbole. He alluded to contentious debates among members of the working group, made up of "a group of people who were competitors and customers of each other" — fabless, foundry and EDA representatives.
"Marketers are always tempted to stretch things," Brock said. He said the working group tried to avoid that pitfall and create a "big nuts-and-bolts document" that describes what a model is and leaving the evaluation of a model's quality to the designers reviewing the checklist.
Trust is critical to business, especially in the fabless-foundry dynamic. The FSA has done the industry a service by providing a standardized mechanism for evaluating, understanding and comparing Spice models. But if designers have legitimate reason to doubt the accuracy, validity or honesty of a completed Spice model checklist, it won't be worth the paper it's printed on.
It remains to be seen whether "self-policing" and/or business ethics will keep foundries from abusing the Spice model checklist, or whether the FSA or another body will have to step in and provide oversight.
Ultimately, given the credibility at stake, Tafoya is probably right — the fact that a reputable foundry has far more to lose than gain by being anything less than completely honest in completing the checklist should act as a sufficient deterrent to fraud.
As David Schwan, a member of the working group and manager of CAD and layout at Micro Linear (San Jose) put it Thursday, "It's essential that we trust what we are getting from the foundry. Things are getting too complicated for us to go look for problems."