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A 0.93 ps-ToF-Resolution 14.6mW NIRS IC with Signal-Aware Optical Frontend and Rotational Modulation Data Converter for Psychiatric Disorders Diagnostics

A 0.93 ps-ToF-Resolution 14.6mW NIRS IC with Signal-Aware Optical Frontend and Rotational Modulation Data Converter for Psychiatric Disorders Diagnostics

Yuxiang Lin, Zhouchen Ma, Zhipeng Guo, Zisheng Dai, Cheng Chen, Yongfu Li, Kea-Tiong Tang, Tianhong Zhang, Guoxing Wang Jian Zhao
2025 IEEE Asian Solid-State Circuits Conference (A-SSCC), pp.256-258
IEEE
2025 IEEE Asian Solid-State Circuits Conference (A-SSCC) (Daejeon, Republic of Korea, 02/11/2025–05/11/2025)
02/11/2025
Frequency-domain analysis Functional near-infrared spectroscopy Hardware Integrated optics Optical coupling Optical crosstalk Optical modulation Optical sensors Power demand Solid state circuits
Functional near-infrared spectroscopy (fNIRS) systems are particularly suited for psychiatric studies due to their mobility and flexibility [1]. Frequency-domain (FD) NIRS utilizes multiple source-detector distances (MD) or carrier frequencies (MF) to assess optical properties at varying tissue depths, with both methods yielding comparable results [2]. While MF FD-NIRS is more complex, it is less sensitive to light source-detector coupling variations, enabling more compact systems with fewer optical components. However, most existing work has focused on MD-based approaches [3-5], with limited exploration of MF methods [6]. Current MF FD-NIRS circuits still faces two main challenges (Fig. 1): First, although dynamic architecture has been proposed to decouple resolution from power consumption [4], using the same power across different carrier frequencies still limits energy efficiency. Second, avalanche photodiode's (APD) intensity-phase crosstalk [7] and common offset complicate the accurate determination of metabolite concentrations, leading to diagnostic inaccuracies. Moreover, offset calibration requires additional hardware, increasing system complexity and cost.
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