SILICON-BASED IMAGE SENSOR WITH IMPROVED READING DYNAMIC RANGE

摘要

In an image sensor, the effective capacitance of the storage node NS of the pixel, which stores the charges (the electrons) collected by the photosensitive element of the pixel, is modified with the aid of a feedback loop 100 which influences the supply VREFP of the follower transistor T3 connected to the storage node, in such a way that the apparent capacitance of the storage node depends on the gain GL of the loop. By modifying the gain, the capacitance of the storage node and therefore the charge/voltage conversion factor, which is inversely proportional to this capacitance, is modified.

主权项

1. An image sensor with active pixels, comprising pixels and reading circuits, each pixel having at least one photosensitive element, a capacitive node for storage of charges generated by the photosensitive element, and a follower transistor, the gate of which is connected to the storage node, the source of which is connected to a column conductor, itself connected to a reading circuit, and the drain of which receives a supply voltage, wherein a feedback loop is provided, this loop having an input connected to the column conductor and an output connected to the drain of the follower transistor in order to provide the supply voltage of the latter, and in that means are provided for modifying the behaviour of the feedback loop as a function of the illumination received.