Serving Eastern Massachusetts
Life Members Society
4:00 PM, Wednesday, 8 February
Evolution of RF Power Transistors: From Si BJT to GaN HEMT
Kamal Alavi, Ph.D., Senior Engineering Fellow, Raytheon Company
RF power is used in communication, radars, and heating. In this talk, the basic and fundamental device and material aspects of transistors for RF power generation will be reviewed in a rigorous and yet easy to understand way. Similarity and differences between requirements for RF power, VLSI, and power switching will be discussed. Technological trends and presently known ultimate performance limitations of each device technology will be shown. Numerous examples form published data and vendor’s web site of commercially available RF transistors will be given to bench mark the present status of the industry. The newly arrived and disruptive gallium nitride HEMT technology fundamentals that are different from all previous RF power transistor technologies will be detailed using a vast body of published literature covering S to W band.
First successful use of RF transistors came with silicon bipolar junction transistors (Si BJT) at UHF and in common base mode configuration. Their application was later extended to L and up to S band frequency range. Advances in MOS technology brought us laterally diffused metal oxide semiconductor (LDMOS) transistor with its ease of use and inherent thermal stability due to being a majority career device. LDMOS has been the workhorse for RF power generation at UHF, L band, and recently S band when high drain voltages 0f 12-50 V are required. Compound III-V semiconductor RF power devices, especially GaAs based ones with their inherent superior electron transport properties over Si , have made steady progress in performance, reliability, and cost over the past three decades. GaAs metal semiconductor field effect transistor (MESFET) was the first device to see wide spread use. Advances in III-V material growth brought us the high electron mobility transistor (HEMT) which just turned 30 years old. The revolutionary concepts of modulation doping, pseudomorphic channel, and pulsed doping turned HEMTs into the device of choice for specialized as well as main stream and large volume consumer electronic applications. The need for high power added efficiency at a single supply voltage awakened another nascent III-V device, the heterojunction bipolar transistor (HBT). HBT’s soon became the device of choice for mobile device power amplifiers in the late 1990’s and the situation remains the same for the foreseeable future.
Wide bandgap semiconductors such as silicon carbide and III-V nitrides have long held the promise of being the ultimate power device. An ancillary benefit of the revolution in solid state lighting has been commercial availability of SiC substrates and AlGaN/ GaN HEMTs for RF power and power switching applications. The cost barrier is further being reduced through intense activities by major R&D facilities and equipment makers for growth of GaN HEMTs directly on 150 mm and 200 mm low cost Si substrates.
Kamal
Tabatabaie-Alavi received the B.S. degree in electrical engineering from
Sharif’s University of Technology, Tehran, Iran, in 1977 with emphasis
on microwaves. He received M.S. and Ph.D. degrees in 1980 and 1984,
respectively, from Massachusetts Institute of Technology, Cambridge, MA.
His graduate work was on InGaAsP/InP based HBTs. He demonstrated the
first InGaAsP hetero-junction photo transistor in 1979 and was winner of
the IEDM best student paper award in 1982.
In May 1984, he joined Raytheon Research Division, Lexington, MA. At Raytheon, he has been directly involved with process integration as well as device and process development of several generations of GaAs based technologies, including MESFETs, pHEMTs, and HBTs. He has served as chairman of Boston chapter of IEEE MTT society, session chair as well as panel chair for CSMANTECH conferences. He is an active member of technical program committee of CSMANTECH. He has authored and co-authored 23 technical papers and holds 12 US patents. His current interests are in GaN based FETs as well as co-integration of III-V compounds with Si.
Dr. Tabatabaie-Alavi is a senior member of IEEE and a senior engineering fellow of Raytheon Company.
The meeting will be held at the Lincoln Lab Auditorium, 244 Wood Street., Lexington, MA at 4:00 PM. Refreshments will be served at 3:30 PM. Registration is in the main lobby. Foreign national visitors to Lincoln Lab require visit requests. Please pre-register by e-mail to reception@ll.mit.edu and indicate your citizenship. Please use the Wood Street Gate. For directions go to http://www.ll.mit.edu/ For other information, contact Len Long, Chairman, at (781)894-3943, or l.long@ieee.org
4:00 PM, Wednesday, 25 January
Weave: A Web-Based Visualization and Analysis Environment, Grand Challenges and Data Democratization
Georges Grinstein, PhD, Professor - Computer Science Department, Director - Institute for Visualization and Perception Research, Director - Center for Biomolecular and Medical Informatics, University of Massachusetts Lowell, Lowell MA 01854
Visualization is a buzzword today, the successful result of many research systems built in the last two decades. However no research system has yet been available that brings forth the state of the art in a publically available and robust system. UMass Lowell with the Open Indicators Consortium (OIC) has developed such a system with version 1.0 having just been released. Weave is an open-source high performance collaborative and highly flexible web-based visual analytics framework. It incorporates a number of approaches that together provide a step toward the solution of one of the grand challenges in visualization, namely visualization for the masses, as well as an attack on several others. We will describe very briefly the system’s requirements, its architecture, work with the OIC, provide some demos of members’ sites and highlight its state of the art aspects, the key being its session state-based architecture.
Georges Grinstein is Professor of Computer Science at the University
of Massachusetts Lowell, head of its Bioinformatics and Cheminformatics
Program, Co-director of its Institute for Visualization and Perception
Research, and of its Center for Biomolecular and Medical Informatics. He
received his Ph.D. in Mathematics from the University of Rochester in
1978.
His work is broad and interdisciplinary, ranging from the perceptual foundations of visualization to techniques for very high-dimensional data visualization to visualization applications to a theory of visualization, with the emphasis on the modeling, visualization, and analysis of complex information systems.
He has over 30 years in academia with extensive private consulting, over 100 research grants, products in use nationally and internationally, several patents, numerous publications in journals and conferences, a new book on interactive data visualization, founded several companies, been the organizer or chair of national and international conferences and workshops in Computer Graphics, in Visualization, and in Data Mining, and has given numerous keynotes. He has mentored over 25 doctoral students and hundreds of graduate students. He has been on the editorial boards of several journals in Computer Graphics and Data Mining, a member of ANSI and ISO, a NATO Expert, and a technology consultant for various public agencies.
For the last eight years he has co-chaired the IEEE InfoVis and VAST contests in visual analytics leading to new research areas; has taught Radical Design, a course teaching students how to innovate with "radical" new products instead of evolutionary ones; is a member of the Homeland Security Center CCICADA; and is co-director of the new Open Indicators Consortium that is developing a web-based interactive collaborative visual analytics system.
The meeting will be held at the Lincoln Lab Auditorium, 244 Wood Street., Lexington, MA at 4:00 PM. Refreshments will be served at 3:30 PM. Registration is in the main lobby. Foreign national visitors to Lincoln Lab require visit requests. Please pre-register by e-mail to reception@ll.mit.edu and indicate your citizenship. Please use the Wood Street Gate. For directions go tohttp://www.ll.mit.edu/ For other information, contact Len Long, Chairman, at (781)894-3943, or l.long@ieee.org