Experts vs. Expertise

By Ed Sperling
The trend in IC design—particularly for large, complex SoCs—is specialization among engineers. There are specialists for layout, for verification, for DFM, for test, and for software, among other things. And there are experts who have a smattering of many of the pieces and can oversee the integration and testing.

Power is different. Because power affects every part of a design, and it has to be dealt with at every step along the way—from initial architecture to final signoff—there is no single expert or even group of experts who can handle that task. In short, everyone needs at least some expertise in this area, while some may need lots of expertise.

“What’s different about power is that it is still a relatively new focus for most people,” said Cary Chin, director of technical marketing for low-power solutions at Synopsys. “It’s also not compartmentalized. And it permeates what every engineer does. It’s not clear it will stay that way. In the past, things that were not compartmentalized eventually were compartmentalized and automated. But over the next three to five years, it certainly looks as if it will stay that way.”

Part of the reason for this has to do with a lack of automation. At this point, there isn’t even a clear-cut way to automate power. While everyone is well aware of battery life, there is no single fix. There are a variety of models being developed that can at least allow architects and design engineers to take accurate readings and make tradeoffs. And those kinds of models do help on the verification side. But truly automating power will require many more steps.

Compounding that is a lack of understanding about how to deal with power. There are gaps in expertise everywhere, and thorny tradeoffs that no one wants to touch.

“Even though power is getting more visibility, there is still a lack of expertise,” said Qi Wang, technical marketing group director for low power and mixed signal at Cadence. “Many customers want to add low-power techniques into their designs but they’re not aware of the obstacles. If you save power you may sacrifice area and timing. It may impact the design schedule. And verification gets harder.”

He noted that globalization is helping somewhat, because big companies do have a fair amount of expertise in this area.

“The rate of growth of expertise in this area is phenomenal in places like China,” he said. “Three or four years ago, people didn’t know what I was talking about. That’s all changed. With companies like Huawei, and other big companies moving their designs there, the rate of producing experts in this area is improving.”

Different vantage points
Who’s proficient at proficient at power and who isn’t frequently is a function of where they’re coming from within the design space. Some people have to deal with power because their designs demand it. Others don’t—at least not yet.

“The level of sophistication on power is quite varied, and the perspective of system makers is often quite different from the view of component makers,” said Chris Rowen, chief technology officer at Tensilica. “Some teams play it strictly by the book—just look at the specs of all the components, add up all the power, divide by battery capacity, and struggle with the answer. They may always not appreciate either the central role of scenario analysis and software-driven power management in making mobile devices battery life and thermal issues tractable. At the same time, some also have gotten a deep appreciation of some subtle issues around power. For example, the leakage current of 45nm and 28nm digital circuits is actually not bad under typical conditions—room temperature and average processing—and only a small fraction of the active power at normal clock frequencies.”

But only small changes in temperature or other random variances produce non-linear effects that can greatly exacerbate leakage. Rowen said some engineers have been burned by these surprises and are starting to invest much more to avoid them.

Field tests
It also helps that consumers are becoming much more savvy about power. They can set preferences on their phones to minimize power consumption, and increasingly understand that bad reception can sap battery power as a device attempts to communicate to find a better signal. They also can spot a problem and communicate about it over the Internet.

That’s exactly what happened with Apple’s iOS 5 operating system. The newest release includes changes to improve battery life. What makes this particularly interesting for the SoC design world is that Apple is a true integrated device manufacturer. It designs the chip, the software that runs on it, the interfaces for the applications that run on top of all of that, as well as the overall platform. In fact if anyone can get it right, it should be Apple. Still, the complexity of a device like an iPhone or an iPad has surpassed even the most advanced technology companies, however.

“It’s really hard to tell where the problem is,” said Chin. “But these days beta testing is happening at the user level. The problems are so complex that companies need population data to determine the problem. Luckily, connected devices continually gather that information. Apple can gather information from 250 million users in the first week of release. If you were to do system-level simulations, how much can you really simulate in six months? We’re seeing public beta testing for that.”

In this case, users actually became part of the expertise needed to test the power on the iPhone—and an extension of the power verification team at Apple.

Short-term and long-term
While this is an interesting development in power verification, most ICs sold into a socket don’t have this luxury. They have to work well, and they have to be competitive from a power, performance and area/cost perspective. They also have to be delivered on time with increasing complexity, meaning everyone in the design chain will need to know something about power, and some engineers will have to know a lot about power.

While some of that expertise may be automated in the future, experts will still be required to solve thorny issues involving power and related issues such as heat for many years to come.

“Low power expertise won’t necessarily secure you a job, but in whatever you do, low power expertise will help you do your job better,” said Wang.