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Presenter: Dr. David Rutledge - California Institute of Technology, Kiyo and Eiko Tomiyasu Professor of Electrical Engineering, Pasedena, California
Supervisor:

Date: Tue, July 17, 2001
Time: 10:00:00 - 11:00:00
Place: EOW 430

ABSTRACT

Abstract

Traditionally, high-power transmitters have been made with vacuum tubes, but solid-state transmitters are becoming increasingly competitive. I will present recent results from our group over a wide range of frequencies. At millimeter-wave frequencies the challenge is to combine the outputs of a large number of transistors efficiently. We recently demonstrated a single-chip amplifier with a 5-W output at 37GHz. The devices uses a quasi-optical array to combine the outputs of 512 gallium-arsenide transistors in free space with a combining loss of 1dB, and a third-order intercept of 50W. The chip was fabricated at the Rockwell Science Center. This chip could have applications for satellite Internet uplinks. At microwave frequencies, we have been concerned with the problem of how to make a high-power transmitter that is suitable for notebook computers. We have demonstrated a 2.4-GHz power amplifier in with a power output of 2W and a power-added efficiency of 40%. The design is an active transformer with eight transistors distributed around a single turn. The chip has an area of 2 square mm. It was fabricated at Conexant with a standard 0.35-micron CMOS process. It employs no bond-wire inductors or off-chip components. At lower frequencies in the HF range, inexpensive power MOSFETs can be used to make very efficient high-power transmitters. We built a 7-MHz amplifier with a pair of STW20NB50 transistors from ST Microelectronics that operates in a new class that combines the advantages of Class E and inverse F. The amplifier produces an output power of 1100W at a drain efficiency of 85%.

Professor Rutledge is Executive Officer for the Electrical Engineering Department at Caltech and Director of Caltech's Lee Center for Advanced Networking. He is the Editor of the IEEE Transactions on Microwave Theory and Techniques. He received the B.A. in Mathematics from Williams College; the M.A. in Electrical Sciences from Cambridge University; and the Ph.D. in Electrical Engineering from the University of California. His research has been in integrated-circuit antennas, active quasi-optics, computer-aided design, and high-efficiency power amplifiers. He has won the Microwave Prize, the Distinguished Educator Award of the Microwave Theory and Techniques Society, the Teaching Award of the Associated Students of Caltech, the Doug DeMaw award of the ARRL, the Third Millennium Award of the IEEE, and he is a Fellow of the IEEE. He is author of the electronics textbook, The Electronics of Radio, published by Cambridge University Press, and co-author of the microwave computer-aided-design software package, Puff, which has sold 30,000 copies.

FREE AND OPEN TO THE PUBLIC
For Further Information Contact:
Dr. J. Bornemann (721 8666)