1. Dengyun Lei is with the School of Integrated Circuits, Heng Wu is with the School of Automation, School of Computer, Guangdong University of Technology, P. R. China
2. Institute of Microelectronics, Peking University, Beijing, P. R. China
3. Science and Technology on Reliability Physics and Application of Electronic Component Laboratory, No.5 Electronics Research Institute of the Ministry of Industry and Information Technology, Guangzhou, P. R. China