1. School of Microelectronics and Solid‐State ElectronicsUniversity of Electronic Science and Technology of ChinaChengdu610054SichuanPeople's Republic of China
2. Tsinghua National Laboratory for Information Science and TechnologyInstitute of Microelectronics, Tsinghua UniversityBeijing100084People's Republic of China
3. Department of Electrical Engineering and Computer ScienceUniversity of Central FloridaOrlandoFL32816USA