Micro EEG/ECG signal's chopper-stabilization amplifying chip for novel dry-contact electrode

Jianhui Sun; Chunxing Wang; Gongtang Wang; Jinhui Wang; Qing Hua; Chuanfu Cheng; Xinxia Cai; Tao Yin; Yang Yu; Haigang Yang; Dengwang Li

doi:10.1088/1674-4926/38/2/025004

J. Semicond. > 2017, Volume 38 > Issue 2 > 025004

SEMICONDUCTOR INTEGRATED CIRCUITS

Micro EEG/ECG signal's chopper-stabilization amplifying chip for novel dry-contact electrode

Jianhui Sun^{1, 2}, Chunxing Wang¹, Gongtang Wang¹, Jinhui Wang⁴, Qing Hua¹, Chuanfu Cheng¹, Xinxia Cai², Tao Yin², Yang Yu², Haigang Yang² and Dengwang Li^{1, 3,}

+ Author Affiliations

Corresponding author: Dengwang Li, Email:dengwang@sdnu.edu.cn

DOI: 10.1088/1674-4926/38/2/025004

Abstract: Facing the body's EEG (electroencephalograph, 0.5-100Hz, 5-100 μV) and ECG's (electrocardiogram, < 100Hz, 0.01-5mV) micro signal detection requirement, this paper develops a pervasive application micro signal detection ASIC chip with the chopping modulation/demodulation method. The chopper-stabilization circuit with the RRL (ripple reduction loop) circuit is to suppress the ripple voltage, which locates at the single-stage amplifier's outputting terminal. The single-stage chopping core's noise has been suppressed too, and it is beneficial for suppressing noises of post-circuit. The chopping core circuit uses the PFB (positive feedback loop) to increase the inputting resistance, and the NFB (negative feedback loop) to stabilize the 40 dB intermediate frequency gain. The cascaded switch-capacitor sample/hold circuit has been used for deleting spike noises caused by non-ideal MOS switches, and the VGA/BPF (voltage gain amplifier/band pass filter) circuit is used to tune the chopper system's gain/bandwidth digitally. Assisted with the designed novel dry-electrode, the real test result of the chopping amplifying circuit gives some critical parameters:8.1 μW/channel, 0.8 μVrms (@band-width=100 Hz), 4216-11220 times digitally tuning gain range, etc. The data capture system uses the NI CO's data capturing DAQmx interface, and the captured micro EEG/ECG's waves are real-time displayed with the PC-Labview. The proposed chopper system is a unified EEG/ECG signal's detection instrument and has a critical real application value.

Key words: EEG/ECG, novel dry-contact electrode, weak and micro signal detection, chopping modulation/demodulation de-noising, gain/band width digitally tuning

References

[1]	Zhou P, Wang F, Liu M X, et al. Study on noise restraint in noncontact electrocardiographic measurement. Chin J Sci Instrum, 2013, 34(10):2226 http://en.cnki.com.cn/Article_en/CJFDTOTAL-YQXB201310010.htm
[2]	Pan L B, Xiang G X, Huang L H, et al. Automatic positioning and sensing microelectrode array (APSMEA) for multi-site electrophysiological recordings. J Neurosci Methods, 2008, 170:123 doi: 10.1016/j.jneumeth.2008.01.007
[3]	Kloh L G. The neural basis of EEG. Clinical Electroencephalography, 198l:12
[4]	Moulahcene F, Bouguechal N E, Youcef B. A low power low noise chopper-stabilized two-stage operational amplifier for portable bio-potential acquisition systems using 90 nm technology. Int J Hybrid Inform Technol, 2014:25 https://www.researchgate.net/publication/283739887_A_Low_Power_Low_Noise_Chopper-Stabilized_Tow-stage_Operational_Amplifier_for_Portable_Bio-potential_Acquisition_Systems_Using_90_nm_Technology
[5]	Cai G J, Shen Y Z. A weak signal sensing amplifier for integrated sensors. Microelectronics, 2004, 34(1):97
[6]	Verma N, Shoeb A, Guttag J V, et al. A micro-power EEG acquisition SoC with integrated seizure detection processor for con-tinuous patient monitoring. 2009 Symposium on VLSI Circuits, 2009
[7]	Zhang F, Apurva M, Richardson A G, et al. A low-power ecog/EEG processing IC with integrated multiband energy extractor. IEEE Trans Circuits Syst I, 2011, 58:2069 doi: 10.1109/TCSI.2011.2163972
[8]	Wu S T, Lin F, Guo D H, et al. Design of CMOS operating amplifier for eliminating DC offset based on chopper technology. Semicond Technol, 2003, 28(8):60
[9]	Xu J W, Fan Q W, Huijsing J H, et al. Measurement and analysis of current noise in chopper amplifiers. J Solid-State Circuit, 2013, 48:1575 doi: 10.1109/JSSC.2013.2253217
[10]	Wu R, Makinwa K A A, Huijsing J H. A chopper currentfeedback instrumentation amplifier with a 1 mHz 1/f noise corner and an AC-coupled ripple reduction loop. IEEE J Solid-State Circuits, 2009, 44:3232 doi: 10.1109/JSSC.2009.2032710
[11]	Van Hellputte N, Kim S, Kim H, et al. A 160 a biopotential acquisition IC with fully integrated IA and motion artifact suppression. IEEE Trans Biomedical Circuits Syst, 2012, 6:552 doi: 10.1109/TBCAS.2012.2224113
[12]	Yoo J, Yan L, El-Damak D. An 8-channel scalable EEG acquisition SoC with patient-specific seizure classification and recording processor. IEEE Solid Circuits, 2013, 48:214 doi: 10.1109/JSSC.2012.2221220
[13]	Enz C C, Vittoz E A, Krummenacher F. A CMOS chopper amplifier. IEEE J Solid-State Circuits, 1987, 22:335 doi: 10.1109/JSSC.1987.1052730
[14]	Harrison R R, Charles C. A low-power low-noise CMOS amplifier for neural recording applications. IEEE J Solid-State Circuits, 2003, 38:958 doi: 10.1109/JSSC.2003.811979
[15]	Masui Y, Yoshida T, Iwata A. Low power and low voltage chopper amplifier without BPF. IEICE Electron Express, 2008, 5(22):967 doi: 10.1587/elex.5.967

Fig. 1. Micro EEG high resolution amplifying & filtering ASIC system

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Fig. 2. Principle of chopping modulation/demodulation.

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Fig. 3. Single-stage chopper amplifying core, PFB/NFB, RRL circuit

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Fig. 4. Sensor offset voltage generation, electronical model

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Fig. 5. Non-overlap two-phase chopper gate.

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Fig. 6. Timing of chopper gate, chopper gate clock feed-through effect

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Fig. 7. Chopper main circuit body RRL architecture

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Fig. 8. Gain/BW digitally tuning VGA/BPF circuit.

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Fig. 9. Spike-free sample/hold circuit.

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Fig. 10. PC-Labview real-time capture, display board

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Fig. 11. 8-channel chopper chip‘s layout-micrograph.

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Fig. 12. Chopper system band-pass simulation.

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Fig. 13. Input equivalent noise simulation before/after chopping

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Fig. 14. Magnitude and phase frequency response of the chopping amplifier.

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Fig. 15. Output noise spectrum of the chopper in DC mode with gain of 100.

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Fig. 16. 8-channel EEG chopper amplifying chip‘s test board

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Fig. 17. ECG signal real capture result.

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Fig. 18. Brain EEG signal captured segment result.

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Fig. 19. Brain forehead EEG test scheme. (a) Eyes-closed. (b) Eyesopen

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Fig. 20. Brain EEG alpha-wave blocked phenomenon

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Table 1. Brain EEG spindles capture segment result

[1]	Zhou P, Wang F, Liu M X, et al. Study on noise restraint in noncontact electrocardiographic measurement. Chin J Sci Instrum, 2013, 34(10):2226 http://en.cnki.com.cn/Article_en/CJFDTOTAL-YQXB201310010.htm
[2]	Pan L B, Xiang G X, Huang L H, et al. Automatic positioning and sensing microelectrode array (APSMEA) for multi-site electrophysiological recordings. J Neurosci Methods, 2008, 170:123 doi: 10.1016/j.jneumeth.2008.01.007
[3]	Kloh L G. The neural basis of EEG. Clinical Electroencephalography, 198l:12
[4]	Moulahcene F, Bouguechal N E, Youcef B. A low power low noise chopper-stabilized two-stage operational amplifier for portable bio-potential acquisition systems using 90 nm technology. Int J Hybrid Inform Technol, 2014:25 https://www.researchgate.net/publication/283739887_A_Low_Power_Low_Noise_Chopper-Stabilized_Tow-stage_Operational_Amplifier_for_Portable_Bio-potential_Acquisition_Systems_Using_90_nm_Technology
[5]	Cai G J, Shen Y Z. A weak signal sensing amplifier for integrated sensors. Microelectronics, 2004, 34(1):97
[6]	Verma N, Shoeb A, Guttag J V, et al. A micro-power EEG acquisition SoC with integrated seizure detection processor for con-tinuous patient monitoring. 2009 Symposium on VLSI Circuits, 2009
[7]	Zhang F, Apurva M, Richardson A G, et al. A low-power ecog/EEG processing IC with integrated multiband energy extractor. IEEE Trans Circuits Syst I, 2011, 58:2069 doi: 10.1109/TCSI.2011.2163972
[8]	Wu S T, Lin F, Guo D H, et al. Design of CMOS operating amplifier for eliminating DC offset based on chopper technology. Semicond Technol, 2003, 28(8):60
[9]	Xu J W, Fan Q W, Huijsing J H, et al. Measurement and analysis of current noise in chopper amplifiers. J Solid-State Circuit, 2013, 48:1575 doi: 10.1109/JSSC.2013.2253217
[10]	Wu R, Makinwa K A A, Huijsing J H. A chopper currentfeedback instrumentation amplifier with a 1 mHz 1/f noise corner and an AC-coupled ripple reduction loop. IEEE J Solid-State Circuits, 2009, 44:3232 doi: 10.1109/JSSC.2009.2032710
[11]	Van Hellputte N, Kim S, Kim H, et al. A 160 a biopotential acquisition IC with fully integrated IA and motion artifact suppression. IEEE Trans Biomedical Circuits Syst, 2012, 6:552 doi: 10.1109/TBCAS.2012.2224113
[12]	Yoo J, Yan L, El-Damak D. An 8-channel scalable EEG acquisition SoC with patient-specific seizure classification and recording processor. IEEE Solid Circuits, 2013, 48:214 doi: 10.1109/JSSC.2012.2221220
[13]	Enz C C, Vittoz E A, Krummenacher F. A CMOS chopper amplifier. IEEE J Solid-State Circuits, 1987, 22:335 doi: 10.1109/JSSC.1987.1052730
[14]	Harrison R R, Charles C. A low-power low-noise CMOS amplifier for neural recording applications. IEEE J Solid-State Circuits, 2003, 38:958 doi: 10.1109/JSSC.2003.811979
[15]	Masui Y, Yoshida T, Iwata A. Low power and low voltage chopper amplifier without BPF. IEICE Electron Express, 2008, 5(22):967 doi: 10.1587/elex.5.967

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Received: 15 September 2016 Revised: 29 November 2016 Online: Published: 01 February 2017

Article Navigation > Journal of Semiconductors > 2017 > 38(2): 025004

Jianhui Sun, Chunxing Wang, Gongtang Wang, Jinhui Wang, Qing Hua, Chuanfu Cheng, Xinxia Cai, Tao Yin, Yang Yu, Haigang Yang, Dengwang Li. Micro EEG/ECG signal's chopper-stabilization amplifying chip for novel dry-contact electrode[J]. Journal of Semiconductors, 2017, 38(2): 025004. doi: 10.1088/1674-4926/38/2/025004 ****J H Sun, C X Wang, G T Wang, J H Wang, Q Hua, C F Cheng, X X Cai, T Yin, Y Yu, H G Yang, D W Li. Micro EEG/ECG signal\'s chopper-stabilization amplifying chip for novel dry-contact electrode[J]. J. Semicond., 2017, 38(2): 025004. doi: 10.1088/1674-4926/38/2/025004.

Citation:

J H Sun, C X Wang, G T Wang, J H Wang, Q Hua, C F Cheng, X X Cai, T Yin, Y Yu, H G Yang, D W Li. Micro EEG/ECG signal\'s chopper-stabilization amplifying chip for novel dry-contact electrode[J]. J. Semicond., 2017, 38(2): 025004. doi: 10.1088/1674-4926/38/2/025004.

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Micro EEG/ECG signal's chopper-stabilization amplifying chip for novel dry-contact electrode

DOI: 10.1088/1674-4926/38/2/025004

1.
College of Physics and Electronics, Shandong Normal University, Jinan 240014, China
2.
Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China
3.
Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, Institute of Bioelectronics, Shandong Normal University, Jinan 240014, China
4.
Department of Electronical and Computer Engineering, North Dakota State University, Fargo, ND 58102, USA

Funds:

Project supported by the National Natural Science Foundation of China (Nos.61527815, 31500800, 61501426, 61471342), the National Key Basic Research Plan (No.2014CB744600), the Beijing Science and Technology Plan (No.Z141100000214002), and the Chinese Academy of Sciences'Key Project (No.KJZD-EW-L11-2)

the National Natural Science Foundation of China 61527815

the National Natural Science Foundation of China 61501426

the Beijing Science and Technology Plan Z141100000214002

the National Natural Science Foundation of China 61471342

the National Natural Science Foundation of China 31500800

the Chinese Academy of Sciences'Key Project KJZD-EW-L11-2

the National Key Basic Research Plan 2014CB744600

More Information

Corresponding author: Dengwang Li, Email:dengwang@sdnu.edu.cn
Received Date: 2016-09-15
Revised Date: 2016-11-29
Published Date: 2017-02-01

Abstract

Abstract

Facing the body's EEG (electroencephalograph, 0.5-100Hz, 5-100 μV) and ECG's (electrocardiogram, < 100Hz, 0.01-5mV) micro signal detection requirement, this paper develops a pervasive application micro signal detection ASIC chip with the chopping modulation/demodulation method. The chopper-stabilization circuit with the RRL (ripple reduction loop) circuit is to suppress the ripple voltage, which locates at the single-stage amplifier's outputting terminal. The single-stage chopping core's noise has been suppressed too, and it is beneficial for suppressing noises of post-circuit. The chopping core circuit uses the PFB (positive feedback loop) to increase the inputting resistance, and the NFB (negative feedback loop) to stabilize the 40 dB intermediate frequency gain. The cascaded switch-capacitor sample/hold circuit has been used for deleting spike noises caused by non-ideal MOS switches, and the VGA/BPF (voltage gain amplifier/band pass filter) circuit is used to tune the chopper system's gain/bandwidth digitally. Assisted with the designed novel dry-electrode, the real test result of the chopping amplifying circuit gives some critical parameters:8.1 μW/channel, 0.8 μVrms (@band-width=100 Hz), 4216-11220 times digitally tuning gain range, etc. The data capture system uses the NI CO's data capturing DAQmx interface, and the captured micro EEG/ECG's waves are real-time displayed with the PC-Labview. The proposed chopper system is a unified EEG/ECG signal's detection instrument and has a critical real application value.
- EEG/ECG,
- novel dry-contact electrode,
- weak and micro signal detection,
- chopping modulation/demodulation de-noising,
- gain/band width digitally tuning

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References(15)

References

[1]	Zhou P, Wang F, Liu M X, et al. Study on noise restraint in noncontact electrocardiographic measurement. Chin J Sci Instrum, 2013, 34(10):2226 http://en.cnki.com.cn/Article_en/CJFDTOTAL-YQXB201310010.htm
[2]	Pan L B, Xiang G X, Huang L H, et al. Automatic positioning and sensing microelectrode array (APSMEA) for multi-site electrophysiological recordings. J Neurosci Methods, 2008, 170:123 doi: 10.1016/j.jneumeth.2008.01.007
[3]	Kloh L G. The neural basis of EEG. Clinical Electroencephalography, 198l:12
[4]	Moulahcene F, Bouguechal N E, Youcef B. A low power low noise chopper-stabilized two-stage operational amplifier for portable bio-potential acquisition systems using 90 nm technology. Int J Hybrid Inform Technol, 2014:25 https://www.researchgate.net/publication/283739887_A_Low_Power_Low_Noise_Chopper-Stabilized_Tow-stage_Operational_Amplifier_for_Portable_Bio-potential_Acquisition_Systems_Using_90_nm_Technology
[5]	Cai G J, Shen Y Z. A weak signal sensing amplifier for integrated sensors. Microelectronics, 2004, 34(1):97
[6]	Verma N, Shoeb A, Guttag J V, et al. A micro-power EEG acquisition SoC with integrated seizure detection processor for con-tinuous patient monitoring. 2009 Symposium on VLSI Circuits, 2009
[7]	Zhang F, Apurva M, Richardson A G, et al. A low-power ecog/EEG processing IC with integrated multiband energy extractor. IEEE Trans Circuits Syst I, 2011, 58:2069 doi: 10.1109/TCSI.2011.2163972
[8]	Wu S T, Lin F, Guo D H, et al. Design of CMOS operating amplifier for eliminating DC offset based on chopper technology. Semicond Technol, 2003, 28(8):60
[9]	Xu J W, Fan Q W, Huijsing J H, et al. Measurement and analysis of current noise in chopper amplifiers. J Solid-State Circuit, 2013, 48:1575 doi: 10.1109/JSSC.2013.2253217
[10]	Wu R, Makinwa K A A, Huijsing J H. A chopper currentfeedback instrumentation amplifier with a 1 mHz 1/f noise corner and an AC-coupled ripple reduction loop. IEEE J Solid-State Circuits, 2009, 44:3232 doi: 10.1109/JSSC.2009.2032710
[11]	Van Hellputte N, Kim S, Kim H, et al. A 160 a biopotential acquisition IC with fully integrated IA and motion artifact suppression. IEEE Trans Biomedical Circuits Syst, 2012, 6:552 doi: 10.1109/TBCAS.2012.2224113
[12]	Yoo J, Yan L, El-Damak D. An 8-channel scalable EEG acquisition SoC with patient-specific seizure classification and recording processor. IEEE Solid Circuits, 2013, 48:214 doi: 10.1109/JSSC.2012.2221220
[13]	Enz C C, Vittoz E A, Krummenacher F. A CMOS chopper amplifier. IEEE J Solid-State Circuits, 1987, 22:335 doi: 10.1109/JSSC.1987.1052730
[14]	Harrison R R, Charles C. A low-power low-noise CMOS amplifier for neural recording applications. IEEE J Solid-State Circuits, 2003, 38:958 doi: 10.1109/JSSC.2003.811979
[15]	Masui Y, Yoshida T, Iwata A. Low power and low voltage chopper amplifier without BPF. IEICE Electron Express, 2008, 5(22):967 doi: 10.1587/elex.5.967

Micro EEG/ECG signal's chopper-stabilization amplifying chip for novel dry-contact electrode

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