A low power linear output current-mediated CMOS imager

Abstract

A novel CMOS current-mediated imager (CMI) is presented with high output linearity. In the proposed structure, the pixel oper ates in triode region , instead of operating in saturation region for conventional currentmediated imagers . As a consequence, the output current is a linear function of the photocurrent at the sensing node. Such a linear feature reduces the DC current consumption by more than a factor of 10 for high linearity applications. Additionally, the corresponding current source /mirror circuit is also presented, aiming to further minimize the linearity distortion caused by the Vds variation.Keywords-Current-mediated imager, low power CMOS imager.is presented in section V. II . CONVENTIONAL CURRENT-MEDIATED IMAGERSA typical 3-T CMOS current-mediated imager is demonstrated in Fig . 1. During the reset phase, M2 and M3 are enabled, and hence a known reference current I re! would flow through the diode-connected active transistor M1. Finally, the reset voltage Vres et at the sensing node Vn is defined by Eq . (1).