ST patent application US20130009041 "Pinned photodiode cmos image sensor with a low supply voltage" by Frédéric Barbier and Yvon Cazaux proposes to use SF M2 gate to source capacitance to boost the FD voltage when TG is on. It's achieved by means of clamp switch CL:
Omnivision application US20130009043 "Image sensor having supplemental capacitive coupling node" by Duli Mao, Hsin-Chih Tai, Vincent Venezia, Howard E. Rhodes, and Sohei Manabe proposes a similar idea with boost signal supplied through an additional capacitor 416 in the pixel:
Omnivision application US20130009043 "Image sensor having supplemental capacitive coupling node" by Duli Mao, Hsin-Chih Tai, Vincent Venezia, Howard E. Rhodes, and Sohei Manabe proposes a similar idea with boost signal supplied through an additional capacitor 416 in the pixel:
