1. Department of Electrical Engineering, National Chung-Hsing University, 250 Kuo Kuang Rd., Taichung 402, Taiwan
2. National Chip Implementation Center, National Applied Research Laboratories, Hsinchu, Taiwan
3. Department of Electronic Engineering, National Chin-Yi University of Technology, 57 Sec. 2 Zhongshan Rd., Taiping Dist., Taichung 411, Taiwan