Micro-Electromechanical Ultra-Compact Non-Dispersive Phase Shifters
James C. M. Hwang
Date: Tuesday, December 6, 2011
Time: 5:30 Reception, Dinner (Optional) 6:00 pm, Lecture 7:00
All IEEE members and guests are welcome to attend.
Cost: Lecture and reception free, Dinner $15
Please RSVP to Roger Kaul, 301-394-4775 or firstname.lastname@example.org.
Recent advances in metamaterials allow non-dispersive phase shifters to be realized, which will greatly simplify the operation of frequency-agile and broadband-modulated phased-array radar and communications systems. Dispersion is only natural, so the phase of a conventional true-time-delay phase shifter varies with frequency. However, by judiciously combining right-handed natural material and left-handed metamaterial with different dispersion characteristics, a phase shifter can have constant phase shift across a wide bandwidth. For example, a composite right/left-handed (CRLH) transmission line can be formed by combining fixed inductors with variable capacitors. The CRLH transmission line can then assume right- or left-handed characteristics depending on the values of the variable capacitors. The variable capacitors can be based on micro-electromechanical (MEM) capacitive switches, which can be monolithically integrated in a CRLH transmission line to realize non-dispersive phased shifters that are light, compact, low loss, low cost, and low power consumption. The additional degrees of freedom afforded by the MEM switches also allow a slow-wave structure to be tightly wrapped around the MEM switches to further reduce the size and loss of the phase shifter while maintaining wideband impedance match. Experimental results obtained on a Ku-band phase-shifter unit cell will be used to illustrate these design principles and performance advantages.
James C. M. Hwang is a Professor of Electrical Engineering and Director of the Compound- Semiconductor Technology Laboratory at Lehigh University. He graduated with a B.S. degree in Physics from National Taiwan University in 1970, and completed M.S. (1973) and Ph.D. (1976) studies in Materials Science at Cornell University. After twelve years of industrial experience at IBM, AT&T, GE, and GAIN, he joined Lehigh University in 1988. His current research interests include micro-electromechanical systems, radio-frequency transistors and integrated circuits, optoelectronics and bio-electromagnetics. He has been a Nanyang Professor at Nanyang Technological University in Singapore and an Advisory Professor at Shanghai Jiao Tong University, East China Normal University and University of Science and Technology of China. He co-founded GAIN and QED; the latter became a public company (IQE). He has published approximately 300 refereed technical papers and has been granted five U. S. patents. He became an IEEE Fellow in 1994. He received the IBM Faculty Award in 2007, the CIE Outstanding Achievement Award, and the WOCC Outstanding Contribution Award in 2011. Currently, he is on leave from Lehigh University serving as a Program Manager at the US Air Force Office of Scientific Research responsible for GHz-THz electronics.