Megapixel time-gated SPAD image sensor for 2D and 3D imaging applications

TLDR

We present a 1‑megapixel single‑photon avalanche diode camera with 3.8 ns time gating and 24 kfps, fabricated in 180 nm CMOS. The sensor employs two pixel types (7‑T and 5.75‑T) with a 9.4 µm pitch, achieving a 13.4 % fill factor in 180 nm CMOS. The camera attains 27 % photon detection probability, 2.0 cps dark count, <550 ps rise/fall, and 120 ps gating variation, enabling 2 m 3‑D imaging with 5.4 mm resolution and sub‑8 mm precision, while supporting dual‑exposure dynamic range and multi‑object detection in time‑of‑flight experiments.

Abstract

We present a 1 Mpixel single-photon avalanche diode camera featuring 3.8 ns time gating and 24 kfps frame rate, fabricated in 180 nm CMOS image sensor technology. We designed two pixels with a pitch of 9.4 µm in 7 T and 5.75 T configurations respectively, achieving a maximum fill factor of 13.4%. The maximum photon detection probability is 27%, median dark count rate is 2.0 cps, variation in gating length is 120 ps, position skew is 410 ps, and rise/fall time is <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>&lt;</mml:mo> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>550</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">p</mml:mi> <mml:mi mathvariant="normal">s</mml:mi> </mml:mrow> </mml:math> , all FWHM at 3.3 V excess bias. The sensor was used to capture 2D/3D scenes over 2 m with resolution (least significant bit) of 5.4 mm and precision better than 7.8 mm (rms). We demonstrate extended dynamic range in dual exposure operation mode and show spatially overlapped multi-object detection in single-photon time-gated time-of-flight experiments.