1. Department of Electronics Engineering, Chung Hua University, Hsinchu, Taiwan, 300, R.O.C
2. Department of Electronics Engineering, National Chiao Tung University, Hsinchu, Taiwan, 300, R.O.C
3. Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University, Tainan, Taiwan, 701, R.O.C