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A 124 dB dynamic range sigma-delta modulator applied to non-invasive EEG acquisition using chopper-modulated input-scaling-down technique

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  • Special Focus on Brain Machine Interfaces and Applications
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Abstract

With the advancement of brain science in recent years, the non-invasive brain-computer interfaces (BCIs) based on electroencephalogram (EEG) acquisition have been widely adopted in various brain-inspired applications. The acquisition of multi-channel microvolts EEG signals corrupted by the motion artifacts (MAs) of up to several volts poses enormous challenges to the design of analog front-end (AFE), especially the analog-to-digital converter (ADC), which is necessary to achieve low noise, wide dynamic range (DR), high accuracy as well as low power. In this paper, a wide DR ΣΔ modulator with chopper-modulated input-scaling-down (CM-ISD) technique has been proposed to deal with large input offset while extending dynamic range. Fabricated in 180 nm CMOS technology, the prototype occupies a core area of 0.32 mm2. With a 40 Hz input signal and 125 Hz Nyquist bandwidth, the measured signal-to-noise ratio (SNR) and signal-to-noise and distortion ratio (SNDR) are 117 and 110 dB, respectively. Thanks to the proposed CM-ISD technique, the modulator is capable of withstanding a full-scale (4.5 Vpp) input whereas the measured DR has been extended from 99 to 124 dB. The power consumption is 2.75 mW under 5 V supply voltage, corresponding to 170.6 dB Schreier figure-of-merit (FoMS). The multi-channel EEG acquisition has been demonstrated based on the proposed modulator, showing its potential in advanced non-invasive BCI systems.

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Acknowledgements

This work was supported by National Natural Science Foundation of China (Grant No. 62174109). The authors would like to thank Dongrui GAO, Jiaxin XIE and Shaofei YING in University of Electronic Science and Technology of China for their help and guidance in the real EEG measurements.

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Authors and Affiliations

  1. Department of Micro/Nano Electronics, Shanghai Jiao Tong University, Shanghai, 200240, China

    Kaiquan Chen, Mingyi Chen, Liang Qi, Guoxing Wang & Yong Lian

  2. China Electronic Cloud Brain (Tianjin) Technology Co.,Ltd., Tianjin, 300309, China

    Longlong Cheng

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  1. Kaiquan Chen
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  2. Mingyi Chen
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  3. Longlong Cheng
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  4. Liang Qi
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  5. Guoxing Wang
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Correspondence to Mingyi Chen.

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Chen, K., Chen, M., Cheng, L. et al. A 124 dB dynamic range sigma-delta modulator applied to non-invasive EEG acquisition using chopper-modulated input-scaling-down technique. Sci. China Inf. Sci. 65, 140402 (2022). https://doi.org/10.1007/s11432-021-3401-6

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  • DOI: https://doi.org/10.1007/s11432-021-3401-6

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