A Low-phase-error FD-fNIRS Readout Circuit with Sub-1V Transimpedance Amplifier and LC-ADC-based Amplitude Control Loop

Kangkang Xu; Shuo Zhang; Zheng Ding; Nan Zeng; Jian Zhao; Mohamad Sawan; Guoxing Wang; Cheng Chen

doi:10.1109/ISCAS66217.2026.11562872

A Low-phase-error FD-fNIRS Readout Circuit with Sub-1V Transimpedance Amplifier and LC-ADC-based Amplitude Control Loop

Kangkang Xu
, Shuo Zhang
, Zheng Ding
, Nan Zeng
, Jian Zhao
, Mohamad Sawan
, Guoxing Wang
, Cheng Chen^*

^*Corresponding author for this work

Shanghai Jiao Tong University
Westlake University

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

Abstract

Frequency-domain functional near-infrared spectroscopy (FD-fNIRS) ultilizes the propagation time and amplitude attenuation of light in tissue to quantify blood oxygen concentration. This enables more detailed monitoring of human brain activity, providing a potential solution for non-invasive and wearable brain-computer interface (BCI) devices. However, the amplitude-phase coupling effect of the comparator in the phase detector introduces phase errors, which in turn leads to inaccuracies in the measurement of light propagation time. To suppress amplitude-phase coupling effect, an amplitude control loop based on the level-crossing analog-to-digital converter (LC ADC) is employed. The utilization of the LC ADC eliminates the need for a high-speed envelope detector, thereby reducing circuit complexity and power consumption. In addition, a sub-1V transimpedance amplifier (TIA) is employed to improve energy efficiency. The proposed structure achieves a phase error of 0.11° and 12 mW power consumption.

Original language	English
Title of host publication	ISCAS 2026 - 2026 IEEE International Symposium on Circuits and Systems
Publisher	Institute of Electrical and Electronics Engineers Inc.
Pages	3436-3440
Number of pages	5
ISBN (Electronic)	9798331577698
DOIs	https://doi.org/10.1109/ISCAS66217.2026.11562872
State	Published - 2026
Externally published	Yes
Event	2026 IEEE International Symposium on Circuits and Systems, ISCAS 2026 - Shanghai, China Duration: 24 May 2026 → 27 May 2026

Publication series

Name	Proceedings - IEEE International Symposium on Circuits and Systems
ISSN (Print)	0271-4310

Conference

Conference	2026 IEEE International Symposium on Circuits and Systems, ISCAS 2026
Country/Territory	China
City	Shanghai
Period	24/05/26 → 27/05/26

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 7 Affordable and Clean Energy

Keywords

Frequency-domain functional near-infrared spectroscopy (FD-fNIRS)
amplitude control loop
level-crossing analog-to-digital converter (LC ADC)

Access to Document

10.1109/ISCAS66217.2026.11562872

Cite this

Xu, K., Zhang, S., Ding, Z., Zeng, N., Zhao, J., Sawan, M., Wang, G., & Chen, C. (2026). A Low-phase-error FD-fNIRS Readout Circuit with Sub-1V Transimpedance Amplifier and LC-ADC-based Amplitude Control Loop. In ISCAS 2026 - 2026 IEEE International Symposium on Circuits and Systems (pp. 3436-3440). (Proceedings - IEEE International Symposium on Circuits and Systems). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/ISCAS66217.2026.11562872

Xu, Kangkang ; Zhang, Shuo ; Ding, Zheng et al. / A Low-phase-error FD-fNIRS Readout Circuit with Sub-1V Transimpedance Amplifier and LC-ADC-based Amplitude Control Loop. ISCAS 2026 - 2026 IEEE International Symposium on Circuits and Systems. Institute of Electrical and Electronics Engineers Inc., 2026. pp. 3436-3440 (Proceedings - IEEE International Symposium on Circuits and Systems).

@inproceedings{0e9a2f757c9f43169ba3c4147e5b2b8a,

title = "A Low-phase-error FD-fNIRS Readout Circuit with Sub-1V Transimpedance Amplifier and LC-ADC-based Amplitude Control Loop",

abstract = "Frequency-domain functional near-infrared spectroscopy (FD-fNIRS) ultilizes the propagation time and amplitude attenuation of light in tissue to quantify blood oxygen concentration. This enables more detailed monitoring of human brain activity, providing a potential solution for non-invasive and wearable brain-computer interface (BCI) devices. However, the amplitude-phase coupling effect of the comparator in the phase detector introduces phase errors, which in turn leads to inaccuracies in the measurement of light propagation time. To suppress amplitude-phase coupling effect, an amplitude control loop based on the level-crossing analog-to-digital converter (LC ADC) is employed. The utilization of the LC ADC eliminates the need for a high-speed envelope detector, thereby reducing circuit complexity and power consumption. In addition, a sub-1V transimpedance amplifier (TIA) is employed to improve energy efficiency. The proposed structure achieves a phase error of 0.11° and 12 mW power consumption.",

keywords = "Frequency-domain functional near-infrared spectroscopy (FD-fNIRS), amplitude control loop, level-crossing analog-to-digital converter (LC ADC)",

author = "Kangkang Xu and Shuo Zhang and Zheng Ding and Nan Zeng and Jian Zhao and Mohamad Sawan and Guoxing Wang and Cheng Chen",

note = "Publisher Copyright: {\textcopyright} 2026 IEEE.; 2026 IEEE International Symposium on Circuits and Systems, ISCAS 2026 ; Conference date: 24-05-2026 Through 27-05-2026",

year = "2026",

doi = "10.1109/ISCAS66217.2026.11562872",

language = "英语",

series = "Proceedings - IEEE International Symposium on Circuits and Systems",

publisher = "Institute of Electrical and Electronics Engineers Inc.",

pages = "3436--3440",

booktitle = "ISCAS 2026 - 2026 IEEE International Symposium on Circuits and Systems",

address = "美国",

}

Xu, K, Zhang, S, Ding, Z, Zeng, N, Zhao, J, Sawan, M, Wang, G & Chen, C 2026, A Low-phase-error FD-fNIRS Readout Circuit with Sub-1V Transimpedance Amplifier and LC-ADC-based Amplitude Control Loop. in ISCAS 2026 - 2026 IEEE International Symposium on Circuits and Systems. Proceedings - IEEE International Symposium on Circuits and Systems, Institute of Electrical and Electronics Engineers Inc., pp. 3436-3440, 2026 IEEE International Symposium on Circuits and Systems, ISCAS 2026, Shanghai, China, 24/05/26. https://doi.org/10.1109/ISCAS66217.2026.11562872

A Low-phase-error FD-fNIRS Readout Circuit with Sub-1V Transimpedance Amplifier and LC-ADC-based Amplitude Control Loop. / Xu, Kangkang; Zhang, Shuo; Ding, Zheng et al.
ISCAS 2026 - 2026 IEEE International Symposium on Circuits and Systems. Institute of Electrical and Electronics Engineers Inc., 2026. p. 3436-3440 (Proceedings - IEEE International Symposium on Circuits and Systems).

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

TY - GEN

T1 - A Low-phase-error FD-fNIRS Readout Circuit with Sub-1V Transimpedance Amplifier and LC-ADC-based Amplitude Control Loop

AU - Xu, Kangkang

AU - Zhang, Shuo

AU - Ding, Zheng

AU - Zeng, Nan

AU - Zhao, Jian

AU - Sawan, Mohamad

AU - Wang, Guoxing

AU - Chen, Cheng

PY - 2026

Y1 - 2026

N2 - Frequency-domain functional near-infrared spectroscopy (FD-fNIRS) ultilizes the propagation time and amplitude attenuation of light in tissue to quantify blood oxygen concentration. This enables more detailed monitoring of human brain activity, providing a potential solution for non-invasive and wearable brain-computer interface (BCI) devices. However, the amplitude-phase coupling effect of the comparator in the phase detector introduces phase errors, which in turn leads to inaccuracies in the measurement of light propagation time. To suppress amplitude-phase coupling effect, an amplitude control loop based on the level-crossing analog-to-digital converter (LC ADC) is employed. The utilization of the LC ADC eliminates the need for a high-speed envelope detector, thereby reducing circuit complexity and power consumption. In addition, a sub-1V transimpedance amplifier (TIA) is employed to improve energy efficiency. The proposed structure achieves a phase error of 0.11° and 12 mW power consumption.

AB - Frequency-domain functional near-infrared spectroscopy (FD-fNIRS) ultilizes the propagation time and amplitude attenuation of light in tissue to quantify blood oxygen concentration. This enables more detailed monitoring of human brain activity, providing a potential solution for non-invasive and wearable brain-computer interface (BCI) devices. However, the amplitude-phase coupling effect of the comparator in the phase detector introduces phase errors, which in turn leads to inaccuracies in the measurement of light propagation time. To suppress amplitude-phase coupling effect, an amplitude control loop based on the level-crossing analog-to-digital converter (LC ADC) is employed. The utilization of the LC ADC eliminates the need for a high-speed envelope detector, thereby reducing circuit complexity and power consumption. In addition, a sub-1V transimpedance amplifier (TIA) is employed to improve energy efficiency. The proposed structure achieves a phase error of 0.11° and 12 mW power consumption.

KW - Frequency-domain functional near-infrared spectroscopy (FD-fNIRS)

KW - amplitude control loop

KW - level-crossing analog-to-digital converter (LC ADC)

UR - https://www.scopus.com/pages/publications/105043519792

U2 - 10.1109/ISCAS66217.2026.11562872

DO - 10.1109/ISCAS66217.2026.11562872

M3 - 会议稿件

AN - SCOPUS:105043519792

T3 - Proceedings - IEEE International Symposium on Circuits and Systems

SP - 3436

EP - 3440

BT - ISCAS 2026 - 2026 IEEE International Symposium on Circuits and Systems

PB - Institute of Electrical and Electronics Engineers Inc.

T2 - 2026 IEEE International Symposium on Circuits and Systems, ISCAS 2026

Y2 - 24 May 2026 through 27 May 2026

ER -

Xu K, Zhang S, Ding Z, Zeng N, Zhao J, Sawan M et al. A Low-phase-error FD-fNIRS Readout Circuit with Sub-1V Transimpedance Amplifier and LC-ADC-based Amplitude Control Loop. In ISCAS 2026 - 2026 IEEE International Symposium on Circuits and Systems. Institute of Electrical and Electronics Engineers Inc. 2026. p. 3436-3440. (Proceedings - IEEE International Symposium on Circuits and Systems). doi: 10.1109/ISCAS66217.2026.11562872

A Low-phase-error FD-fNIRS Readout Circuit with Sub-1V Transimpedance Amplifier and LC-ADC-based Amplitude Control Loop

Abstract

Publication series

Conference

UN SDGs

Keywords

Access to Document

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Cite this