March 27, 2009
Colloquium Speaker: James Hwang
James C. M. Hwang 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, quantum-dot and quantum-dash infrared lasers, and ultraviolet emitters and detectors. He has been a Nanyang Professor at Nanyang Technological University in Singapore and an Advisory Professor at Shanghai Jiaotong University in China. He co-founded GAIN and QED; the latter became a public company (IQEP). He has published more than 200 technical papers and has been granted four U. S. patents.
Radio-frequency (RF) micro-electromechanical systems (MEMS) such as relay switches and phase shifters promise significant advantages in performance, size, weight, power and cost for phased-array radar and communications systems. However, the application of RF MEMS in space lags behind that of MEMS sensors and actuators mainly because of packaging and reliability issues. This talk highlights recent advances in microencapsulated packaging and dielectric material improvement, which improved the lifetime of RF MEMS switches to several hundred billion cycles of operation. Initial results and plans for space qualification of RF MEMS technology are discussed. A novel design of phase shifters based on a slow-wave structure tightly wrapped around the switches is also described, which can further enlarge the performance and size advantages as well as improving the yield and reliability.