Microwave Engineering Europe - October 2007 - (Page 22)

22 CMOS RF RF design team touts CMOS spin for 3G PAs By Peter Clarke, EE Times Europe s it possible to make a low-cost CMOS power amp for 3G cell phones that can operate with the power efﬁciency and robustness of a gallium-arsenide PA? Acco Semiconductor (Saint Germain en Laye, France) believes it has found a way. But observers questioned whether the company’s MASMOS technology can deliver as promised. And one analyst said the issue of CMOS PAs for 3G could be moot as more front-end modules appear that house the power amp along with ﬁltering and a CMOS controller. CMOS has been used for GSM cell phone power amps and for the PA requirements of Bluetooth and wireless LANs. But for the more-complex modulation schemes and higher frequencies of evolved 3G and WiMax, GaAs or similar technology has been necessary. “The main difference between the GaAsbased technologies and the CMOS technology available today for power ampliﬁers is the breakdown voltage of the devices,” said Denis Masliah, founder and chief technology ofﬁcer of Acco. “In saturated ampliﬁers, for very high-efﬁciency regimes, the voltage across the device can reach 12 V or more for a 3-V bias. And in linear amps, the back-off from the saturation makes it necessary to have an equivalent voltage excursion to limit distortion at the highest power levels. “Furthermore, it is necessary to accept [impedance] mismatch from the antenna on the devices. [That] can produce a large voltage across the device, and can destroy it if its voltage capability is too low,” said Masliah. Acco’s MASMOS technology, he said, can “solve this breakdown issue for all CMOS technologies available for RF today, from 180 nm to 65 nm. MASMOS has a gain capability equivalent to GaAs-based devices and a breakdown of over 14 V routinely.” Masliah said the company is “ﬁling a cluster of patents” on its CMOS power ampliﬁer concept but wouldn’t say exactly what MASMOS is, or what Acco has done to improve the breakdown immunity of CMOS. He would only acknowledge that MASMOS is more than just a design or architectural tweak. But if the new technology amounts to something physical in the process, does that make it nonstandard CMOS? I “This is something we don’t want to discuss,” Masliah said. “It is scalable with technology from 90 nm to 65 nm, 45 nm and so on. It is applicable to any CMOS foundry. It can be done on SOI wafers. Our goal is to have products in handsets in 2009.” Acco hopes to tap a multibillion-dollar market, transforming itself into a fabless chip company in the process. The company has been performing RF IC design services since 1994. Acco’s Masliah: MASMOS to hit cells in 2009 “We’ve worked with 20 different companies – either system companies that wanted their own chip or semiconductor companies [that have outsourced] overﬂow work” to Acco, said Masliah. Then came what Masliah calls the “breakthrough” in the use of CMOS for the implementation of power ampliﬁers. He went to Pond Venture Partners Ltd. (London, England) believing the technology could transform his company from a design services operation into a fabless semiconductor house. Pond was sufﬁciently impressed with Acco and its CMOS power ampliﬁer to join with Partech International and put up $10 million in venture capital. Half of that money was given to Masliah early in 2007 to pay for the manufacture of prototypes to prove his concept. Acco was also able to attract Jamie Urquhart, former chief operating ofﬁcer at ARM and now a partner with Pond, to sign on as interim CEO. “The technology could have application beyond the PA,” Urquhart said. “But if Acco only focuses on the cell phone PA application, the market is big enough to make it worthwhile.” Stan Bruederle, research vice president with Gartner Inc., doesn’t dispute the size of the market but said the case for CMOS in wideband CDMA and Edge has not been made to date, because of the need for a broad range of power with linear operation. “Ampliﬁcation can be backed off from 10 W to run at 2 W, but you can still have an instantaneous peak of 10 W. The result is you are running at 10 or 5 percent efﬁciency most of the time to support the peak signals.” Meanwhile, said Bruederle, “front-end modules are becoming popular that include ﬁltering in the package with the PA and a CMOS controller. A move to CMOS, he said, could be unnecessary “once the PA is contained in a module.” The total annual market for PAs, including wireless LANs and handsets, was $1.85 billion in 2006, up from $1.43 billion in 2005, according to Bruederle. It will almost certainly top $2 billion this year. Handsets now routinely have two or three PAs on board as Bluetooth and Wi-Fi capabilities have been added. “It’s hard to displace GaAs. There’s no evidence [the PA market] is going to CMOS; if anything, it is going to GaAs,” he said. “I haven’t seen a compelling argument for CMOS amps yet, and the trend toward modules works against integration.” Gerard Winpenny, CTO of Nujira Ltd. (Cambridge, England), argued that moving CMOS PAs beyond GSM handsets and Bluetooth into “evolved 3G” and WiMax applications, where modulation schemes are more complex and carrier frequencies higher, would be difﬁcult. He acknowledged that a CMOS technology that performed more like GaAs, as Acco is promising, could reduce cost in handsets. But “claims are easy to make,” Winpenny said. “The proof of the pudding will be in the eating.” This article has been reprinted courtesy of EE Times Europe. Microwave Engineering Europe ● October 2007 ● www.mwee.com 022_MWEE.indd 22 21/09/07 15:46:25 http://www.mwee.com

Table of Contents Feed for the Digital Edition of Microwave Engineering Europe - October 2007

Microwave Engineering Europe - October 2007 Contents Comment News CMOS RF: Si-On-Sapphire Goes Mainstream Cover Feature: New Data Protection Concept for UHF RFID Tags CMOS RF: RF Design Team Touts CMOS Spin for 3G PAs Wireless HID – Are You Following the Standard to Another “Average” Product Development? Phase Optimisation of the RF Front-End Direct Synthesis of UWB-WiMedia Signal Generation 4G Chips to Target 700 MHz Applications Femtocells Mobilize to Fight Wi-Fi in the Home Products Product Feature: AXIEM Pioneers the Future of EM Technology Calendar

Microwave Engineering Europe - October 2007

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