时间：2018年9月27日（星期四）上午10:00

地点：遗传学楼308会议室

报告题目： Low Noise CMOS Circuit Techniques for Biopotential Sensing

报告人： 郑嘉炜 博士

联系人：秦亚杰

Faithful recording of the biopotential signal is the prerequisite for the diagnosis and treatment of various diseases. Typical local field potentials of bio-signals such as ECG, EEG and ERG lie between 0.5 Hz and 500 Hz with amplitudes ranging from tens of µV to several mV. To pick-up the tiny bio-signal low-noise bio-interface circuitry is needed. This talks focuses on the analysis of noise issues and integrated circuit designs for low-frequency biomedical applications.
First, the circuit-level noise reduction techniques in CMOS circuitry is investigated. Chopper stabilization and auto-zeroing are two popular techniques to mitigate low-frequency noises, but they both have issues. Chopping will generate ripple caused by the amplifier’s input offset voltage and auto-zeroing will result in the aliasing of the wideband noise. We propose to use the method of harmonic transfer matrix to analyze circuitries that employ chopping and auto-zeroing. Based on the analysis results, a ripple-free chopper amplifier prototype is proposed.
Second, a low-noise chopper capacitively-coupled instrumentation amplifier (CCIA) for recording bio-potential is designed. It features a digital-assisted DC-electrode offset-cancellation loop. It achieves a noise spectrum of 47 nV/sqrtHz and is capable of handling ±50 mV electrode offset.
Third, a low-power fully-integrated analog front-end for bio-potential sensors is proposed. The signal conditioning circuitry consists of an integrating sampler and a 12-bit SAR ADC. Measurement results show that the analog front-end achieves an in-band gain of 58dB and an input-referred noise spectrum density of 46 nV/sqrtHz that consumes 9.2 µW in total. The prototype IC has been experimented with capturing ECG on human beings.

Short Biography:
ZHENG Jiawei received the B. Sc. Degree in microelectronics from Fudan University, Shanghai, China, in 2012 and the Ph. D. Degree in Electrical and Computer Engineering from the Hong Kong University of Science and Technology (HKUST), Kowloon, Hong Kong, in 2018, where he is now working as a post-doctoral fellow. His research interests include the design of mixed-signal circuits and systems for biomedical applications.