Preamplifier Design Strategies for Capacitive Sensing of Electrophysiological Signals

Yijing Zhang; Sotir Ouzounov; Mohammed Meftah; Eugenio Cantatore; Pieter Harpe

doi:10.1109/ICECS202256217.2022.9970991

Preamplifier Design Strategies for Capacitive Sensing of Electrophysiological Signals

Yijing Zhang, Sotir Ouzounov, Mohammed Meftah, Eugenio Cantatore, Pieter Harpe

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Academic › peer-review

2 Citations (Scopus)

1 Downloads (Pure)

Abstract

Non-contact capacitive electrodes are very suitable for wearable devices to acquire electrophysiological signals in an unobtrusive and long-term way. However, due to its poorly-defined and low electrode capacitance (Ce), its front-end amplifier requires a large biasing resistance (e.g., > 100 GΩ) to maintain a sub-Hz high-pass frequency and low circuit noise. This paper compares two amplifier structures, i.e., a voltage amplifier (VA) and a charge amplifier (CA), each with three biasing strategies, i.e., pseudo resistors, switched resistors and reset switches. These, in total six, amplifier designs were fabricated in a standard 180nm CMOS technology and compared in terms of their input impedance, transfer function and input-referred noise. As final result, the VA and CA structures have comparable performance. In terms of biasing network, the pseudo resistor can achieve hundreds of GΩ, the switched-resistor only reaches several GΩ due to parasitics, and the reset switch achieves a TΩ resistance when it is shut off, and therefore results in the lowest high-pass frequency and the best noise performance.

Original language	English
Title of host publication	ICECS 2022 - 29th IEEE International Conference on Electronics, Circuits and Systems, Proceedings
Publisher	Institute of Electrical and Electronics Engineers
Pages	1-4
Number of pages	4
ISBN (Electronic)	978-1-6654-8823-5
DOIs	https://doi.org/10.1109/ICECS202256217.2022.9970991
Publication status	Published - 2022
Event	29th IEEE International Conference on Electronics, Circuits and Systems, ICECS 2022 - Glasgow, United Kingdom Duration: 24 Oct 2022 → 26 Oct 2022

Conference

Conference	29th IEEE International Conference on Electronics, Circuits and Systems, ICECS 2022
Country/Territory	United Kingdom
City	Glasgow
Period	24/10/22 → 26/10/22

Bibliographical note

Funding Information:
ACKNOWLEDGMENT This work with project number 14663 is financed by the Dutch Research Council (NWO). We also kindly acknowledge EUROPRACTICE for its MPW and design tool support.

Funding

ACKNOWLEDGMENT This work with project number 14663 is financed by the Dutch Research Council (NWO). We also kindly acknowledge EUROPRACTICE for its MPW and design tool support.

Keywords

capacitive electrode
charge amplifier
electrophysiological signal acquisition
Preamplifier
pseudo resistor
reset switch
switched resistor
voltage amplifier

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10.1109/ICECS202256217.2022.9970991

Cite this

Zhang, Y., Ouzounov, S., Meftah, M., Cantatore, E., & Harpe, P. (2022). Preamplifier Design Strategies for Capacitive Sensing of Electrophysiological Signals. In ICECS 2022 - 29th IEEE International Conference on Electronics, Circuits and Systems, Proceedings (pp. 1-4). Article 9970991 Institute of Electrical and Electronics Engineers. https://doi.org/10.1109/ICECS202256217.2022.9970991

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title = "Preamplifier Design Strategies for Capacitive Sensing of Electrophysiological Signals",

abstract = "Non-contact capacitive electrodes are very suitable for wearable devices to acquire electrophysiological signals in an unobtrusive and long-term way. However, due to its poorly-defined and low electrode capacitance (Ce), its front-end amplifier requires a large biasing resistance (e.g., > 100 GΩ) to maintain a sub-Hz high-pass frequency and low circuit noise. This paper compares two amplifier structures, i.e., a voltage amplifier (VA) and a charge amplifier (CA), each with three biasing strategies, i.e., pseudo resistors, switched resistors and reset switches. These, in total six, amplifier designs were fabricated in a standard 180nm CMOS technology and compared in terms of their input impedance, transfer function and input-referred noise. As final result, the VA and CA structures have comparable performance. In terms of biasing network, the pseudo resistor can achieve hundreds of GΩ, the switched-resistor only reaches several GΩ due to parasitics, and the reset switch achieves a TΩ resistance when it is shut off, and therefore results in the lowest high-pass frequency and the best noise performance.",

keywords = "capacitive electrode, charge amplifier, electrophysiological signal acquisition, Preamplifier, pseudo resistor, reset switch, switched resistor, voltage amplifier",

author = "Yijing Zhang and Sotir Ouzounov and Mohammed Meftah and Eugenio Cantatore and Pieter Harpe",

note = "Funding Information: ACKNOWLEDGMENT This work with project number 14663 is financed by the Dutch Research Council (NWO). We also kindly acknowledge EUROPRACTICE for its MPW and design tool support. ; 29th IEEE International Conference on Electronics, Circuits and Systems, ICECS 2022 ; Conference date: 24-10-2022 Through 26-10-2022",

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doi = "10.1109/ICECS202256217.2022.9970991",

language = "English",

pages = "1--4",

booktitle = "ICECS 2022 - 29th IEEE International Conference on Electronics, Circuits and Systems, Proceedings",

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Zhang, Y, Ouzounov, S, Meftah, M, Cantatore, E & Harpe, P 2022, Preamplifier Design Strategies for Capacitive Sensing of Electrophysiological Signals. in ICECS 2022 - 29th IEEE International Conference on Electronics, Circuits and Systems, Proceedings., 9970991, Institute of Electrical and Electronics Engineers, pp. 1-4, 29th IEEE International Conference on Electronics, Circuits and Systems, ICECS 2022, Glasgow, United Kingdom, 24/10/22. https://doi.org/10.1109/ICECS202256217.2022.9970991

Preamplifier Design Strategies for Capacitive Sensing of Electrophysiological Signals. / Zhang, Yijing; Ouzounov, Sotir; Meftah, Mohammed et al.
ICECS 2022 - 29th IEEE International Conference on Electronics, Circuits and Systems, Proceedings. Institute of Electrical and Electronics Engineers, 2022. p. 1-4 9970991.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Academic › peer-review

TY - GEN

T1 - Preamplifier Design Strategies for Capacitive Sensing of Electrophysiological Signals

AU - Zhang, Yijing

AU - Ouzounov, Sotir

AU - Meftah, Mohammed

AU - Cantatore, Eugenio

AU - Harpe, Pieter

N1 - Funding Information: ACKNOWLEDGMENT This work with project number 14663 is financed by the Dutch Research Council (NWO). We also kindly acknowledge EUROPRACTICE for its MPW and design tool support.

PY - 2022

Y1 - 2022

N2 - Non-contact capacitive electrodes are very suitable for wearable devices to acquire electrophysiological signals in an unobtrusive and long-term way. However, due to its poorly-defined and low electrode capacitance (Ce), its front-end amplifier requires a large biasing resistance (e.g., > 100 GΩ) to maintain a sub-Hz high-pass frequency and low circuit noise. This paper compares two amplifier structures, i.e., a voltage amplifier (VA) and a charge amplifier (CA), each with three biasing strategies, i.e., pseudo resistors, switched resistors and reset switches. These, in total six, amplifier designs were fabricated in a standard 180nm CMOS technology and compared in terms of their input impedance, transfer function and input-referred noise. As final result, the VA and CA structures have comparable performance. In terms of biasing network, the pseudo resistor can achieve hundreds of GΩ, the switched-resistor only reaches several GΩ due to parasitics, and the reset switch achieves a TΩ resistance when it is shut off, and therefore results in the lowest high-pass frequency and the best noise performance.

AB - Non-contact capacitive electrodes are very suitable for wearable devices to acquire electrophysiological signals in an unobtrusive and long-term way. However, due to its poorly-defined and low electrode capacitance (Ce), its front-end amplifier requires a large biasing resistance (e.g., > 100 GΩ) to maintain a sub-Hz high-pass frequency and low circuit noise. This paper compares two amplifier structures, i.e., a voltage amplifier (VA) and a charge amplifier (CA), each with three biasing strategies, i.e., pseudo resistors, switched resistors and reset switches. These, in total six, amplifier designs were fabricated in a standard 180nm CMOS technology and compared in terms of their input impedance, transfer function and input-referred noise. As final result, the VA and CA structures have comparable performance. In terms of biasing network, the pseudo resistor can achieve hundreds of GΩ, the switched-resistor only reaches several GΩ due to parasitics, and the reset switch achieves a TΩ resistance when it is shut off, and therefore results in the lowest high-pass frequency and the best noise performance.

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KW - reset switch

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M3 - Conference contribution

AN - SCOPUS:85145358391

SP - 1

EP - 4

BT - ICECS 2022 - 29th IEEE International Conference on Electronics, Circuits and Systems, Proceedings

PB - Institute of Electrical and Electronics Engineers

T2 - 29th IEEE International Conference on Electronics, Circuits and Systems, ICECS 2022

Y2 - 24 October 2022 through 26 October 2022

ER -

Preamplifier Design Strategies for Capacitive Sensing of Electrophysiological Signals

Abstract

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Bibliographical note

Funding

Keywords

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