Performance Improvement Analysis of fNIRS IC
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A Receiver (RX) for functional near-infrared spectroscopy (fNIRS) IC was previously designed to obtain hemodynamics of the human brain, requiring high SNR measurements. It is largely composed of TIA, PGA, and OTA-C-based matched filters, along with a single-slope ADC. However, a dead-zone problem arises in the conventional design, wherein an unstable voltage level appears in a specific section near 0V among signals measured using the IC system. This phenomenon persists despite offset calibration with its own current DAC, as each IC exhibits an inconsistent input offset value in the comparator. Revised IC is proposed to solve this problem. In this work, we address the issue by removing the current MSB detector and allocating a period for the ADC's comparator to verify the sign information of the PGA output. The dead-zone effect is mitigated by enhancing the system to provide discharge direction information and quantize it. Revised IC had a 0.48-bit ENOB enhancement in simulation domain, but failed to measure full scheme due to design-time issues.
Abstract
A Receiver (RX) for functional near-infrared spectroscopy (fNIRS) IC was previously designed to obtain hemodynamics of the human brain, requiring high SNR measurements. It is largely composed of TIA, PGA, and OTA-C-based matched filters, along with a single-slope ADC. However, a dead-zone problem arises in the conventional design, wherein an unstable voltage level appears in a specific section near 0V among signals measured using the IC system. This phenomenon persists despite offset calibration with its own current DAC, as each IC exhibits an inconsistent input offset value in the comparator. Revised IC is proposed to solve this problem. In this work, we address the issue by removing the current MSB detector and allocating a period for the ADC's comparator to verify the sign information of the PGA output. The dead-zone effect is mitigated by enhancing the system to provide discharge direction information and quantize it. Revised IC had a 0.48-bit ENOB enhancement in simulation domain, but failed to measure full scheme due to design-time issues.
참고문헌 (11)
- Scholkmann, F., "A review on continuous wave functional near-infrared spectroscopy and imaging instrumentation and methodology", NeuroImage, 85(1), pp.6~27 (2014)
- J. -K Choi, "Time-Divided Spread-Spectrum Code-Based 400fW-Detectable Multichannel fNIRS IC for Portable Functional Brain Imaging", IEEE Journal of Solid-State Circuits, 51(2), pp.484~495 (2016)
- J. -K Choi, "A time-divided spread-spectrum code based 15pW-detectable multi-channel fNIRS IC for portable functional brain imaging", IEEE International Solid-State Circuits Conference-(ISSCC) Digest of Technical Papers, pp.1~3 (2015)
- Hongchin Lin, "A simple high-speed low current comparator", IEEE International Symposium on Circuits and Systems (ISCAS), pp.713~716 (2000)
- Jorge Lagos, "A 1-GS", s, 12-b, single-channel pipelined ADC with dead-zone-degenerated ring amplifiers, 2019, pp.54(3), 646~658
- Bart M. Nicolaï, "Time-resolved and continuous wave NIR reflectance spectroscopy to predict soluble solids content and firmness of pear", Postharvest Biology and Technology, 47(1), pp.68~74 (2008)
- David T. Delpy, "Estimation of optical pathlength through tissue from direct time of flight measurement", Physics in Medicine & Biology, 33(12), pp.1433~1442 (1988)
- George Turin, "An introduction to matched filters", IRE transactions on Information theory, 6(3), pp.311~329 (1960)
- Kiseok Song, "An impedance and multi-wavelength near-infrared spectroscopy IC for non-invasive blood glucose estimation", IEEE Journal of solid-state circuits, 50(4), pp.1025~1037 (2015)
- Anand Veeravalli, "A CMOS transconductance amplifier architecture with wide tuning range for very low frequency applications", IEEE Journal of Solid-state circuits, 37(6), pp.776~781 (2002)
- HeungJun Jeon, "Offset voltage analysis of dynamic latched comparator", IEEE 54th International Midwest Symposium on Circuits and Systems(MWSCAS), pp.1~4 (2011)