A complementary metal-oxide-semiconductor image sensor with 2.0 e ^- random noise and 110 ke^- full well capacity and noise measurement of pixel transistors using column source follower readout circuits

A low noise complementary metal-oxide-semiconductor (CMOS) image sensor without degradation of saturation performance has been developed by using column amplifiers of the gains of about 1.0 in a lateral overflow integration capacitor technology. The 1/4-in., 4.5-mm pitch, 800^H × 600^V pixels CMOS image sensor fabricated by a 0.18-μm 2-poly 3-metal CMOS technology including a buried pinned photo-diode structure has achieved fully linear response, 0.98 column readout gain, 104-μV/e ^- conversion gain, 2.0-e^- total random noise, 110,000-e- full well capacity and 95-dB dynamic range in one exposure. Moreover, the random noise of the developed readout circuits has been reduced to 0.5-e^- without degradation of saturation performance. As a result, the behaviors of pixel noises have been accurately measured. Operating condition dependency of the random noise generated by pixel transistors has been measured by using the developed readout circuits. In addition, considering the result of the measurements, we optimize pixel operating condition.