the PTC obtained by performing the same measurement with
the column-level gain is set to 1. In this case, the PTC
collapses around 1.02 V. This time, the saturation originates
from the pixel. This curve allows the measurement of the
pixel full well capacity. Using the measured conversion gain
of 160μV/e− the pixel full well capacity is about 6400 e−.
Typical values of full well capacities for pixels based on
photodiodes with similar area are of the order of 10000 e−, but
for conversion gains of about 50μV/e−. The pixel presented
in this work features a higher conversion gain of about
160μV/e−. The voltage swing of the in-pixel source follower
stage is about 1 V, which corresponds to about 6250 e− for
this particular conversion gain. Therefore, a FWC higher than
6400 e− would be unnecessary since it would saturate the
source follower stage. This limit can be overcome to extend
the dynamic range by reducing the conversion gain when the
imager operates in high illumination level [5] [19]. This work
does not focus on extending the dynamic range for high signal
level but rather by pushing down the noise floor. Now all
the noise reduction techniques presented in this work remain
compatible with all the techniques used to reach high full well
capacities with pixels based on pinned photodiodes [5] [19].