A Multimode CMOS Vision Sensor With On-Chip Motion Direction Detection and Simultaneous Energy Harvesting Capabilities

This work presents a
${128}\times {128}$
multi-function CMOS vision sensor with motion direction detection (MDD) and simultaneous energy harvesting (EH) capability, featuring: 1) light weight template-based optical flow (OF) algorithm for on-chip MDD with high energy efficiency and small area overhead; and 2) independent imaging and energy harvesting (EH) operations using vertically stacked N+/PW and PW/DNW+DNW/PSUB junctions without photodiode reconfiguration. Fabricated in
$0.18\mu \text{m}$
standard CMOS, this work demonstrates the first CMOS vision sensor featuring both MDD and EH modes within a compact pixel pitch of
$4.75\mu \text{m}$
. With a power consumption of
$10.5\mu \text{W}$
at 15fps in MDD mode, the chip prototype achieves a motion sensing figure-of-merit (MS-FoM) of 171 pJ/pixel
$\cdot $
frame, which is 30% better than the state-of-the-art MDD sensors. The proposed EH configuration achieves continuous power generation at 267pW/lx/mm
²
irrespective of the imaging/MDD operation, demonstrating a
$1.56\times $
improvement over prior arts.