Analysis and estimation of NEP and DR in CMOS TOF-3D image sensor based on MDSI

This paper presents an accurate analysis of noise equivalent power (NEP) and optical dynamic range (DR), for CMOS-3D image sensor based-on, indirect time-of-flight (TOF) technique with its derived algorithm: MDSI (multiple double short time integration). Considering, in addition, the maximum distance-range, scene features, and appropriate noise analysis a new approach for estimating NEP and DR has been proposed; exhibiting high correlation with MDSI principle, in contrast to the conventional approach where both parameters are only a function of incident-light power and integration time, which provides a general approach for all sort of image sensor including ordinary 2D image. Further analysis shows that NEP, for CMOS 3D-MDSI sensor, is at least 10 times the commonly quoted, and corresponds to the minimum required LASER-pulse power to achieve 90% of a given distance-range measurement, under a specific background light illumination (indoor/outdoor applications). Based-on the present analysis, an optimization criteria has been developed and applied to the design of 3D-MDSI sensor using 0.6 μm standard CMOS process; a good agreement between experiment results and the conducted analysis has been found.