1. School of Microelectronics, Southern University of Science and Technology, Shenzhen, China
2. School of Microelectronics, the Engineering Research Center of Integrated Circuits for Next-Generation Communications, Ministry of Education, and the GaN Device Engineering Technology Research Center of Guangdong, Southern University of Science and Technology, Shenzhen, China
3. Department of Electrical and Computer Engineering, National University of Singapore, Queenstown, Singapore