Startup to take CMOS RF PAs to a new level

Startup to take CMOS RF PAs to a new level

Technology News |
By Jean-Pierre Joosting

The Sunnyvale, California-based startup, which traces its roots back to 1994, believes it can cash in on the growing opportunity for RF front end chips for cell phones and Internet of Things (IoT) products by strapping power amplifiers (PAs) to the same economic engine that has propelled most other types of chips: complementary metal–oxide–semiconductor (CMOS) process technology.

PAs are required for communications in modern cell phones and many IoT-connected products. The vast majority are built using silicon germanium or gallium arsenide technology rather than CMOS. ACCO has since 2007 been developing a technology to enable PAs to be built using CMOS, which the firm believes will enable them to take advantage of CMOS integration, Moore’s Law and the growing market for smartphones and IoT devices.

“Our strong belief is the only way you are going to get more functionality and lower cost at the same time is with CMOS integration,” said Greg Caltabiano, ACCO’s president and CEO. “That’s what has happened in every other industry where people said it couldn’t happen.”

Caltabiano noted that computers built in the 1960s and 70s relied on discrete semiconductors rather than integrated CMOS chips. Not that long ago, he said, Wi-Fi chips weren’t done in CMOS, either. “And then a few companies came through and figured out how to do it,” Caltabiano said. “And once they figured out how to do it and therefore did the integration, they became gigantic companies and wiped out their competition.”

Building PAs in CMOS has traditionally been difficult because the devices require very high voltage to operate, Caltabiano said. CMOS transistors traditionally break down at relatively low voltages.

Caltabiano said some companies have attempted to build CMOS PAs by including redundant transistors to mitigate the problem of transistors breaking. But, he said, the multiple transistors exacerbated the problem of distortion in PA signals.

To solve the problem, Caltabiano said, ACCO developed a new type of transistor. “It’s a special type of transistor that can carry a lot of voltage and is very linear,” he said.

ACCO, which does most of its development work at an R&D center outside of Paris, got its start as a French design services firm in 1994. By 2007, the firm had evolved into a chip company and secured $10 million in funding.

ACCO spent the past nine years relatively quietly refining its technology before emerging last October to announce the AC26120, a CMOS multi-mode, multi-band PA for smartphones and IoT applications. Caltabiano said the company has several other product introductions planned for this fall.

”The front end is complicated, and it’s just gonna get more complicated,” Caltabiano said. At the same time that front end complexity increases, economic pressures are pushing the cost of smartphones down, he added.

”Because of that, you need to have a whole different equation,” Caltabiano said. “And that equation is what has driven the whole electronics industry. That’s why an iPhone has more computing power than a Cray [supercomputer] did when I was in college. It’s just CMOS integration.”

Caltabiano said ACCO currently has between 60 and 70 employees, but that the company plans to grow its headcount in the wake receiving a $35 million funding infusion last month from French investment bank Bpifrance and several other investors in France and the U.S.

Developing a new type of transistor was a long process, Caltabiano said. “That’s why we’ve been in stealth mode for a while and haven’t had a lot of press. We’ve kind of been a little bit shy about it,” he said. “The reason why we did this big funding round is that now we have product and now we are going to market.”

Dylan McGrath covers the semiconductor industry for EE Times.

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