1. State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, China
2. Key Laboratory of Smart Microsystem, Ministry of Education, Tsinghua University, Beijing 100084, China
3. Beijing Advanced Innovation Center for Integrated Circuits, Beijing 100084, China
4. China Mobile Research Institute, Beijing 100053, China
5. Beijing Key Laboratory of Optoelectronic Measurement Technology, Beijing Information Science & Technology University, Beijing 100192, China