UCSB Engineering

Stephen Long

Professor

Contacts

Department of Electrical and Computer Engineering
University of California
Santa Barbara, CA 93106-9560

tel: (805) 893-3965
fax: (805) 893-3262
long@ece.ucsb.edu

Research Description

The central theme of my current research projects is rather practical: use unconventional digital and analog circuits, high performance devices and fabrication technologies to address problems in high speed electronics such as microwave power amplifiers, circuits for fiber communications, and high speed signal processing.
RF ICs for Communications

1. High Efficiency RF Power Amplifiers. Circuit techniques and devices for increasing the efficiency of CMOS, MESFET, and HBT RF power amplifiers are under investigation. Switching mode Class D, E and F designs are of primary interest. GaN HEMT implementations for very high power. (Nokia, Cree).

2. Low phase noise VCOs. CMOS and HEMT VCO designs utilizing power combining (passive transformer) or dual resonant tank circuits to obtain improved phase noise performance.

Research Groups

• Long Research Group

Biography

Professor Long joined the UCSB faculty in 1981 where his research has included state-of-the-art devices and ICs. The central theme of his current research projects is rather practical: use unconventional digital and analog circuits, high performance devices and fabrication technologies to address significant problems in high speed electronics such as low power circuits and IC interconnections, high speed signal processing, and microwave analog integrated circuits for personal communications. He has coauthored a textbook, Gallium Arsenide Digital Integrated Circuit Design, with Prof. Butner (Computer Engineering) that encompasses device physics and models, circuit design, and CAD tools. Prior to joining UCSB, from 1974 to 1977 he was a Senior Engineer and Manager of Semiconductor Engineering at Varian Associates, Palo Alto, CA. From 1978 to 1981 he was employed by Rockwell International Science Center, Thousand Oaks, CA as a member of the technical staff. Dr. Long received the IEEE Microwave Applications Award in 1978 for development of InP millimeter wave devices. In 1988 he was a research visitor at GEC Hirst Research Centre, U.K. In 1994 he was a Fulbright research visitor at the Signal Processing Laboratory, Tampere University of Technology, Finland and a visiting professor at the Electromagnetics Institute, Technical University of Denmark. He was a research visitor at HP/Agilent EESof division in 1999. He is a senior member of the IEEE and a member of the American Scientific Affiliation.

Awards/Honors

• Fulbright Senior Research Fellowship, 1994

Selected Publications

• Compound Semiconductor Digital Integrated Circuit Technology, Chap. 69 - 72 in VLSI Handbook, 2nd Ed., 2007, 2007, S. I. Long, D. B. Estreich
• A 5 GHz CMOS Low Phase Noise Transformer Power Combining VCO, 2006 IEEE Radio Frequency IC (RFIC) Symposium, 2006, 113-116, P. Lai and S. Long
• A GaN HEMT Class F Amplifier at 2 GHz with > 80% PAE, 2006 IEEE Compound Semiconductor IC Symposium, 2006, 96-99, D. Schmelzer and S. Long
• A High Efficiency Class E GaN HEMT Power Amplifier at 1.9 GHz, IEEE Microwave and Wireless Components Lett., Vol. 16, #1,, 2006, pp. 22-24, H. Xu, S. Gao, S. Heikman, S. Long, U. Mishra and R. York
• A Low Power and Low Noise p-HEMT Ku Band VCO, IEEE Microwave and Wireless Components Lett., Vol. 16, #3, 2006, 131-133, V. Manan and S. Long
• A 5GHz pHEMT Transformer-Coupled VCO, 2005 IEEE Radio Frequency IC (RFIC) Symposium, 2005, 135-138, P. Lai and S. Long
• A Dual Band (10/16 GHz) pHEMT VCO, European Gallium Arsenide and Other Compound Semiconductors Application Symposium, EGaAs2005, 2005, 261-264, V. Manan and S. Long
• Design Analysis and Circuit Enhancements for High Speed Bipolar Flip-Flops, IEEE J. Solid State Cir., Vol. 40, #5,, 2005, pp. 1166 – 1174, T. E. Collins, V. Manan and S. Long