he dream of being able to stay connected anywhereand at any time has finally come true with the advent

of smartphones in late 2006. Since then smartphones haveproliferated rapidly. In 2010, 300 million smartphoneswere shipped worldwide, up nearly 75 percent from 2009.Soon more than half of the communication systems onchips (SoCs) in the cellular market will be geared forsmartphones. Aside from delivering high throughputsenabled by 3G/4G communication processing, such SoCsoffer integrated support for myriad peripheral functionsincluding Wi-Fi, GPS, Bluetooth, and FM radio. More-over, these highly sophisticated SoCs will have computa-tion power upwards of a few GHz hosting powerfuloperating systems that enable innovations and customiza-tions essential to create feature rich multimedia services ina portable handheld device.

In this issue of Topics in Circuits for CommunicationsSeries, we have selected three articles that mark recentprogress in the communications semiconductor industryfor highly integrated transceiver SoCs that enable futuretrends in broadband feature-rich portable communicationdevices.

Smartphones exemplify such portable communicationsdevices, which are starting to rival personal computers withan equally rich feature set, full-fledged operating systems,and a large variety of end-user applications. While technol-ogy advancements enable higher and higher transistorcounts in smartphone application processors, the ability toextract additional performance while staying within apower envelope is becoming a challenge. In the first arti-cle, “GreenDroid: Exploring the Next Evolution in Smart-phone Application Processors,” the authors describe newarchitecture techniques to address challenges with auto-matically generated energy-efficient coprocessors. Theauthors demonstrate the utility of these techniques toimprove the efficiency of a mobile application processorrunning applications under the Android operating system.Estimates show that energy per instruction can be reducedby as much as 90 percent.

A key differentiator of smartphone from traditional cel-

lular devices is its ability to provide high throughput con-nectivity not only to the base station, but also to a plethoraof peripheral devices such as headsets, laptops, cameras,and even TVs. Currently, peripheral connectivity compris-es wireless interfaces via embedded Bluetooth and Wi-Fi,as well as wired interfaces primarily via USB. With emerg-ing high throughput wireless personal area networks suchas IEEE 802.15.3c and IEEE 802.11ad based on 60 GHzmillimeter-wave transmission, smartphones will soon pro-vide instant wireless connectivity to any peripheral devicewithout the inconvenience of plugging in a USB cable. Thesecond article, “Single-Element and Phased-ArrayTransceiver Chipsets for 60-GHz Gb/s Communications,”surveys the most recent development of highly integratedSoC’s geared for draft IEEE 802.15.3C and 802.11.ad stan-dards. The authors provide a broad overview of 60-GHzapplications, and describe system and circuit design tech-niques to implement SoCs that are compact and powerefficient. The authors further address challenges in thedesign of a high-performance (i.e., low RF loss) yet low-cost package that enables the integration of an antennaalong with the SoC in a compact module. Demonstrating achipset capable of delivering 2-Gb/s uncompressed video,this article represents remarkable progress made in thisarea that will one day further enhance the user experiencein next-generation smartphones. Readers interested in thistopic may refer to two related articles published previouslyin our series in August and December 2005.

Increased integration level and feature sets in smart-phone SoCs would not be possible without advances incomplementary metal oxide semiconductor (CMOS) tech-nology, which has reduced its minimum feature size byroughly 40 percent every 18 months. However, with thesteady decrease in feature size (e.g., now at 32 nm), cir-cuits have become more prone to process variation, anddesigns to meet the aggressive performance targets inemerging standards have become increasingly difficult. Toharness the full benefit of integration in deep submicronCMOS technology, therefore, requires both circuit andarchitecture innovations. One technique that has become

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TOPICS IN INTEGRATED CIRCUITS FOR COMMUNICATIONS

Charles Chien Zhiwei Xu Stephen Molloy

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increasingly popular utilizes the higher gate density toimplement sophisticated digital processing to assist theanalog/RF circuits, prone to process variation, to achievethe required signal fidelity. In the final article, “Equaliza-tion Techniques for Nonlinear Analog Circuits,” theauthor employs equalization to correct for nonlinear dis-tortions in analog circuits, which may be viewed as non-ideal communication channels creating distortion betweentheir inputs and outputs. The author illustrates the effec-tiveness of the proposed technique in several ICs imple-mented for data conversion and RF transmission, whichachieved high performance and yield while consuming lowpower. Readers interested in this topic may refer to tworelated articles published previously in our series in August2005 and April 2009.

We would like to take this opportunity to thank all theauthors and reviewers for their contributions to this series.Future issues of this series will continue to cover circuittechnologies that are enabling new and emerging commu-nication systems. If the reader is interested in submitting apaper to this series, please send your paper title and anabstract to any of the Series Editors for consideration.

BIOGRAPHIESCHARLES CHIEN (charles.chien@creonexsystems.com) is president of CreoNexSystems, which focuses on technology development for next-generationcommunication systems. Previously he held various key roles at Conexant

Systems, SST Communications, and Rockwell. In his career he has architect-ed several key products including a CMOS/SiGe chipset for multimedia overcoax, IEEE 802.11abg WLAN RF CMOS transceiver and GaAs PA/RF switches,a wireless audio CMOS chipset for home theatre in a box, CDMA2000 cellu-lar RF CMOS transceivers, and low-power wireless networked sensors. Hewas also an assistant adjunct professor at the University of California at LosAngeles (UCLA) from 1998 to 2009. His interests focus mainly on thedesign of SoC solutions for wireless multimedia and networking applica-tions. He has published in various journals and conferences, and hasauthored a book entitled Digital Radio Systems on a Chip. He received hisB.S.E.E. from the University of California at Berkeley, and M.S. and Ph.D.from UCLA. He served as a member of the technical program committee ofISSCC from 1998 to 2006.

ZHIWEI XU received B.S. and M.S. degrees from Fudan University, Shanghai,China, and his Ph.D. from UCLA, all in electrical engineering. He held indus-try positions with G-Plus Inc., SST Communications, Conexant Systems, andNXP Inc., where he did development for wireless LAN and SoC solutions forproprietary wireless multimedia systems, CMOS cellular transceivers, multi-media over cable systems, and TV tuners. He is currently with HRL laborato-ries, working on software-defined radios, high-speed ADCs, and analogVLSI. He has published in various journals and conferences, made one con-tribution to the Encyclopedia of Wireless and Mobile Communications, andhas five granted patents.

STEPHEN MOLLOY received M.S. and Ph.D. degrees in electrical engineeringfrom UCLA in 1993 and 1997, respectively, where his research focused onlow-power circuits and architectures for video signal processing. This workled to the award of the Showman Prize from UCLA in 1997, and resulted inover a dozen conference and journal publications. He received his B.S.degree in electrical engineering from Rensselaer Polytechnic Institute in1991. He served as Associate Editor of the IEEE Journal of Solid-State Cir-cuits from 2001 to 2004 and was a member of the Technical ProgramCommittee of the IEEE International Solid-State Circuits Conference from1998 until 2005. He is currently vice president of engineering at Qual-comm, leading architecture development.

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