Fixed pattern noise from charge transfer loss in CCD imager

It has been analyzed theoretically and verified experimentally that fixed pattern noise (FPN) is generated by the charge transfer loss when the charge in the CCD imager device generated by photoelectric conversion is imaged with a charge partitioning mode. This is done by removing the unnecessary nonsignal charge and reading out the signal charge. The result shows that the transfer loss due to the removal must be less than 10−4 to achieve even an ordinary picture quality with signal-to-noise (SN) ratio of 60 dB when the signal in the charge partitioning mode is one-tenth the total charge. Furthermore, for a high-quality image with SN ratio above 70 dB, the transfer loss in reading two kinds of charge must be less than 10−5 which is almost a perfect charge transfer.