A 134×132 4-Tap CMOS Indirect Time-of-Flight Range Imager Using In-Pixel Memory Array With 10 Kfps High-Speed Mode and High Precision Mode
Chia-Chi Kuo, Rihito Kuroda
Abstract
This article presents a prototype 4-tap indirect time-of-flight (iToF) CMOS imager with high-speed (HS) range imaging capacity. The sensor features an HS charge modulator, in-pixel memory array, and sub-frame ToF operation, enabling up to 10 Kfps range imaging with eight recording frames and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$<$</tex-math> </inline-formula> 1.82% depth noise for 0.3–1.4 m range under HS mode. This sensor also operates in high-precision (HP) mode, achieving <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$<$</tex-math> </inline-formula> 1.77% depth noise for the 0.4–5.4 m range at 90 frames/s by averaging the subframe signals. With a pixel size of 22.4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{H}$</tex-math> </inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 16 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{V}$</tex-math> </inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> m and 134 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{H}$</tex-math> </inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 132 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{V}$</tex-math> </inline-formula> 4-tap pixel array, the sensor successfully demonstrated precise depth imaging under HP mode and clear 3-D imaging for rapid motion objects under HS mode. The potential application of the sensor and future improvements are also discussed.