1. Department of Precision Instrument,
Tsinghua University, Beijing 100084, China.
2. State Key Laboratory of Precision Measurement Technology and Instruments,
Tsinghua University, Beijing 100084, China.
3. Beijing Advanced Innovation Center for Integrated Circuits, Beijing 100084, China.
4. School of Instrument Science and Opto-Electronic Engineering,
Beijing Information Science and Technology University, Beijing 100016, China.