Yang Wendi, Jiang Hanjun, Yin Yue, Wang Zhihua
IEEE Trans Biomed Circuits Syst. 2021 Aug;15(4):655-665. doi: 10.1109/TBCAS.2021.3084152. Epub 2021 Sep 15.
An ultra-low-power low-noise analog front end (AFE) is presented in this work, aiming for long-term ECG with clear P-waves for clinical diagnose. The chopper amplifier with passive noise filter and PWM based offset cancellation results in an input-reference noise of 0.39 μVrms, which shows 3.7X noise improvements among the state-of-the-art designs. With the digital offset cancellation by the pulse-width modulation wave, the AFE achieves a low input-referred dc offset of 0.4 μV among 9 tested chips and a low drift under 30 μV. A dynamic scale ADC with low-power comparator strategy prevents the instability and signal-loss, achieving an SFDR of 71.6 dB. The proposed AFE achieves a noise-efficient-factor (NEF) of 2.4 with a power consumption of 4 μW. The fabricated chip is demonstrated in a miniature prototype for long-term ECG monitoring application, presenting a clear ECG waveform with visible P-wave. The simultaneously ECG recording with a medical grade 12-lead ECG Holter shows the effective acquisition of the prototype, proofing the better noise performance.
本文介绍了一种超低功耗低噪声模拟前端（AFE），旨在用于长期心电图监测，以获取清晰的P波用于临床诊断。采用带有无源噪声滤波器的斩波放大器和基于脉宽调制（PWM）的失调消除技术，使得输入参考噪声为0.39 μVrms，与现有最先进设计相比，噪声降低了3.7倍。通过脉宽调制波进行数字失调消除，该AFE在9个测试芯片中实现了0.4 μV的低输入参考直流失调以及低于30 μV的低漂移。采用低功耗比较器策略的动态量程模数转换器（ADC）可防止信号不稳定和丢失，实现了71.6 dB的无杂散动态范围（SFDR）。所提出的AFE在功耗为4 μW时实现了2.4的噪声效率因子（NEF）。所制造的芯片在用于长期心电图监测应用的微型原型中得到了验证，呈现出带有可见P波的清晰心电图波形。与医用级12导联心电图动态记录仪同时进行的心电图记录显示了该原型的有效采集，证明了其更好的噪声性能。
