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Open AccessArticle

High-Linearity High-Resolution Time-of-Flight Linear-Array Digital Image Sensor Using Time-Domain Feedback

1
Graduate School of Science and Technology, Shizuoka University, Hamamatsu, Shizuoka 432-8011, Japan
2
Research Institute of Electronics, Shizuoka University, Hamamatsu, Shizuoka 432-8011, Japan
*
Author to whom correspondence should be addressed.
Sensors 2021, 21(2), 454; https://doi.org/10.3390/s21020454
Received: 28 October 2020 / Revised: 4 January 2021 / Accepted: 6 January 2021 / Published: 11 January 2021
(This article belongs to the Section Physical Sensors)
This paper presents a high-linearity high-resolution time-of-flight (ToF) linear-array digital image sensor using a time-domain negative feedback technique. A coarse ToF measurement loop uses a 5-bit digital-to-time converter (DTC) and a delayed gating-pulse generator for time-domain feedback to find the zero of the difference between ToF and the digital estimate of the gating-pulse delay while maintaining a constant operating point of the analog readout circuits. A fine ToF measurement uses a delta-sigma modulation (DSM) loop using the time-domain feedback with a bit-stream signal form. Because of the self-contained property of the DSM for low distortion and noise exploited by the oversampling signal processing, the proposed technique provides high-linearity and high-range resolution in the fine ToF measurement. A prototype ToF sensor of 16.8 × 16.8 μm2 two-tap pixels and fabricated in a 0.11 μm (1P4M) CMOS image sensors (CIS) process achieves +0.9%/−0.47% maximum nonlinearity error and a resolution of 0.24 mm (median) for the measurement range of 0–1.05 m. The ToF sensor produces an 11-bit fully digital output with a ToF measurement time of 22.4 ms. View Full-Text
Keywords: CMOS image sensor (CIS); short-pulse; time-of-flight (ToF); indirect ToF; depth sensing CMOS image sensor (CIS); short-pulse; time-of-flight (ToF); indirect ToF; depth sensing
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MDPI and ACS Style

Kim, J.; Yasutomi, K.; Kagawa, K.; Kawahito, S. High-Linearity High-Resolution Time-of-Flight Linear-Array Digital Image Sensor Using Time-Domain Feedback. Sensors 2021, 21, 454.

AMA Style

Kim J, Yasutomi K, Kagawa K, Kawahito S. High-Linearity High-Resolution Time-of-Flight Linear-Array Digital Image Sensor Using Time-Domain Feedback. Sensors. 2021; 21(2):454.

Chicago/Turabian Style

Kim, Juyeong; Yasutomi, Keita; Kagawa, Keiichiro; Kawahito, Shoji. 2021. "High-Linearity High-Resolution Time-of-Flight Linear-Array Digital Image Sensor Using Time-Domain Feedback" Sensors 21, no. 2: 454.

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