A 1.8V 16μA 136.5dB DR PPG/NIRS Recording IC using Noise Shaping Triple Slope Light to Digital Converter

作者：Mengyu Li, Shuang Song, Dehong Wang, Feijun Zheng, Tian Yang, Yalong Wan, Kai Huang, Zhichao Tan, Menglian Zhao · 年份：2023 · DOI：10.1109/cicc57935.2023.10121288 · 被引用次数：7 · 研究领域：Non-Invasive Vital Sign Monitoring、ECG Monitoring and Analysis、EEG and Brain-Computer Interfaces

Photoplethysmography (PPG) monitoring can provide vital signs like heart rate (HR), heart rate variability (HRV), and blood oxygen saturation $\left(\mathrm{SpO}_{2}\right)$ non-invasively. Moreover, with other monitoring modalities, the PPG channel is becoming prevalent in wearable devices for fitness, glucose, blood pressure, etc., applications [1]. The PPG channel usually puts a stringent requirement on readout design to cope with the extremely low AC/DC (perfusion index < 0.1 %) [2]. On-chip pinned-photodiodes (PPDs) have been used with very low power consumption $(2.63 \mu \mathrm{W})$ for the PPG readout [3] at the cost of very limited DR and linearity. Direct light-to-digital converters (LDC) have been proposed in [4, 5, 6], achieving more than 130dB DR. However, their SNDR in the AC path is still limited to $\lt 90 \mathrm{~dB}$. A PPG readout with higher EOB in the AC path is required for ambulatory monitoring. Meanwhile, power consumption should be minimized to prolong the battery lifetime.