An Analysis of Fixed Pattern Noise (FPN) for the Amplified MOS Intelligent Imager

It has been shown that the fixed pattern noise (FPN) at the dark state of AMI is not caused by fluctuations in FET gain and photodiode dark current, but is cused by that of FET threshold voltage on each pixel. The threshold voltage fluctuation for each pixel was measured within±12 mVpp. The FPN caused by this fluctuations can be eliminated by a software subtraction to give a value of more than 18 dB. Light exposure adds another FPN, due to the sum of the aperture ratio fluctuations and stray capacitance. Visual FPN at high illumination levels, however, is quite small and acceptable for practical use.