1. Mitsubishi Electric Research Laboratories (MERL), 201 Broadway, 8th Floor, Cambridge, Massachusetts 02139, USA
2. Center for Power Electronics Systems, The Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24060, USA
3. Microsystems Technology Laboratories, Massachusetts Institute of Technology (MIT), 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA
4. Department of Electrical and Computer Engineering, Holonyak Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, 208 N. Wright St., Urbana, Illinois 61801, USA
5. Mitsubishi Electric Corporation, Advanced Technology R&D Center, 8-1-1, Tsukaguchi-honmachi, Amagasaki City 661-8661, Japan
6. Mitsubishi Electric Corporation, Information Technology R&D Center, 5-1-1, Ofuna, Kamakura City 247-8501, Japan