Device and method of fitted variable gain analog-digital conversion for an image sensor

摘要

The variable gain analog-to-digital conversion device ( 1 ) for an image sensor comprises at least one N-bit non-linear coarse first converter ( 21 ) receiving a pixel voltage signal (Vpix) and at least one M-bit linear fine second converter ( 22 ) connected to the first converter ( 21 ) in order for the device to supply a binary word of N+M bits relating to the voltage level of the pixel. The first converter ( 21 ) comprises comparison means ( 33 ) for comparing the voltage level of the pixel with one or more voltage thresholds (V 0 to V 4 ) delimiting voltage ranges within the voltage dynamic range of the sensor. The successive voltage ranges represent areas of illumination of the pixel ranging from a weakly lit area to a strongly lit area. The first comparator supplies an N-bit binary word relating to the area of illumination determined for the pixel. The second converter comprises conversion adaptation means for converting the voltage pixel signal to a number of bits less than or equal to M, depending on the N-bit binary word from the first converter.