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3D imaging technologies have become prevalent for diverse applications such as user identification, interactive user interfaces with AR/VR devices, and self-driving cars. Direct time-of-flight (D-ToF) systems, LiDAR sensors, are desirable for long-distance measurements in outdoor environments because they offer high sensitivity to weak reflected light and high immunity to background light thanks to the spatiotemporal correlation of SPADs 1, 2. SPAD-based LiDAR sensors suffer from a large amount of ToF data generated by complicated time-to-digital converters (TDC), resulting in limited spatial resolution and frame rate compared with indirect ToF (I-ToF) sensors. Recently, LiDAR sensors embedding histogramming TDCs have been reported to generate depth information to reduce the required output bandwidth 3-6. However, they still adopt a large number of memories in pixel, a complicated signal processor, or a column-parallel TDC scheme with scanning optics.
Kim et al. (Sat,) studied this question.