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16 May 2003 Accurate estimation of conversion gain and quantum efficiency in CMOS imagers
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We present a new technique for accurate estimation of quantum efficiency, conversion gain, and noise in imagers. The traditional mean-variance method provides an erroneous estimation of these parameters for a non-linear device. Quantum efficiency, estimated by the mean-variance method, changes with the illumination level, a result that is inconsistent with theory. The estimation error can be easily larger than 50%, at mid-level illumination, and results from incorrect modeling of the transfer function. This is corrected by using non-linear estimation methods that force the slope of the photon transfer function to be proportional to the conversion gain. This results in accurate modeling of the signal dependence of the conversion gain, and in turn, accurate estimation of quantum efficiency and noise. By applying both methods to the measured data gathered from the same mega-pixel imager operated under different biasing conditions, it is shown that the non-linear estimation method provides a reliable and accurate estimation of quantum efficiency and noise, while the mean-variance method over-estimates quantum efficiency and under-estimates noise.
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Bedabrata Pain and Bruce R. Hancock "Accurate estimation of conversion gain and quantum efficiency in CMOS imagers", Proc. SPIE 5017, Sensors and Camera Systems for Scientific, Industrial, and Digital Photography Applications IV, (16 May 2003);

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