I know how a 3 Transistor CMOS camera pixel works. As I understand, 4T CMOS pixels have one additional transistor that connects the photodiode to a so-called floating node.
What is that floating node and what is it good for? Seems like a storage for photo-generated electrons, but I thought CMOS pixels give you voltage, not charges (light CCD's...).
Maybe it's good for multi-integration to reduce readout noise (think I was reading that somewhere)?
Any help is welcome, including good hints for further reading on the principle of camera pixels.
