Low energy, low noise wireless sensor SoC for wearable healthcare application

Abstract

Wearable healthcare is a promising research area which expects to shift the healthcare paradigm from the expensive hospital-centric therapies to the low-cost patient-centric disease management in personal daily life. To address this demand, this dissertation investigates unique Wearable-Body Sensor Network (W-BSN) environment. The scope of this dissertation includes from wearable healthcare system level considerations to bio-potential readout integrated circuit level design issues. To measure weak bio-potential signals, such as Electroencephalography (EEG), Electrocardiography (ECG), and Thoracic Impedance Variance (TIV) with low-power consumption and high Signal-to-Noise-Ratio (SNR), 1) Common-Mode (CM) interference related issues; and 2) problems on Skin-Electrode-Interface imperfection were investigated based on experiments, and derived a wearable bio-potential signal acquisition model so as to provide the requirements of designing a low-noise bio-potential readout front-end. An ultra-low power continuous-time Chopper-Stabilized Capacitive-Coupled Instrumentation Amplifier (CS-CCIA), which optimizes circuit noise; enhances CMRR and gain accuracy; boosts input impedance; and enlarges the Electrode DC Offset (EDO) tolerable range, is proposed for wearable EEG monitoring. Compared with the state-of-the-art IA designs, the proposed IA improves the most of the challenging requirements specified in IFCN standards. To continuously monitor cardiac rhythms, a low-power System-on-Chip (SoC) is developed to record TIV of 0.1ohm and ECG signals with sensitivity of 3.17V/ohm and SNR >40dB. It is possible because of a high quality (Q-factor >30) balanced sinusoidal current source and low-noise reconfigurable readout electronics. A cm-range 13.56MHz fabric inductor coupling is adopted to start/stop the SoC remotely. In addition, a 5% duty-cycled Body Channel Communication (BCC) is exploited for 0.2nJ/b 1Mbps energy efficient external data communication. The proposed SoC ...