CMOS IMAGE SENSOR WITH WIDE DYNAMIC RANGE

摘要

A CMOS image sensor having the wide dynamic range is provided to have an improved operating range in a low-voltage environment by classifying the light intensity of the wide range by utilizing the ON-OFF property of PMOS. The potential level of a pixel out node(25) is changed by the signal charge generated in the photo diode(26). A select transistor(24) changes the bias of the source stage by potential variation of the pixel out node. The access transistor(27) outputs the potential level by the low select signal to a column select line. First and second DRC devices(28,29) control the overflow of the signal charge according to the intensity of the light. The first DRC device is the PMOS transistor. The second DRC device is the NMOS transistor of which source is connected to the pixel out node. The gate of each transistor is commonly connected to the overflow drain(OFD) node.