IEEE Trans Biomed Circuits Syst. 2020 Jun;14(3):516-524. doi: 10.1109/TBCAS.2020.2979931. Epub 2020 Mar 10.
A multi-channel analog front-end (AFE) ASIC for wearable EEG recording application is presented in this article. Two techniques, namely chopping stabilization (CS) and time-division-multiplexing (TDM) are combined in a unified manner to improve the input-referred noise and the system level common-mode rejection ratio (CMRR) for multi-channel AFE. With the proposed TDM/CS structure, multiple channels can share single second-stage amplifier for significant reduction in chip size and power consumption. Dual feedback loops for input impedance boosting as well as electrode offset cancellation are incorporated in the system. Implemented in a 0.18-μm CMOS process, the AFE consumes 24 μW under 1 V supply. The input referred noise is 0.63 μV in 0.5 Hz-100 Hz and the input impedance is boosted to 560 MΩ at 50 Hz. The measured amplifier intrinsic CMRR and system-level AFE CMRR are 89 dB and 82 dB, respectively.
本文提出了一种用于可穿戴 EEG 记录应用的多通道模拟前端 (AFE) ASIC。本文采用斩波稳定 (CS) 和时分复用 (TDM) 两种技术，以统一的方式提高多通道 AFE 的输入参考噪声和系统级共模抑制比 (CMRR)。通过所提出的 TDM/CS 结构，多个通道可以共享单个第二级放大器，从而显著减小芯片尺寸和功耗。系统中还集成了用于输入阻抗提升和电极偏移消除的双反馈环。该 AFE 采用 0.18μm CMOS 工艺实现，在 1V 电源下消耗 24μW。在 0.5Hz-100Hz 范围内，输入参考噪声为 0.63μV，在 50Hz 时，输入阻抗提升至 560MΩ。测量得到的放大器固有 CMRR 和系统级 AFE CMRR 分别为 89dB 和 82dB。
