1. School of Microelectronics and Communication Engineering, Chongqing University, Chongqing, China
2. Chongqing Key Laboratory of Bio-Perception and Intelligent Information Processing and the School of Microelectronics and Communication Engineering, Chongqing University, Chongqing, China
3. School of Engineering, The University of Warwick, Coventry, U.K.
4. Department of Electrical and Electronic Engineering, Chongqing University of Technology, Chongqing, China