1. Department of Electrical Engineering, Chang Gung University, Taoyuan City, Taiwan
2. IC Design Department, Phison Electronics Corporation, Miaoli, Taiwan
3. Department of Electronic and Electrical Engineering and the Institute of Communications Engineering, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
4. Department of Electrical Engineering and the Institute of Communications Engineering, National Tsing Hua University, Hsinchu, Taiwan