Charge-coupled device with wide dynamic range

Abstract

This device has, on one and the same component: an image zone having a first array of at least one line of cells integrating an electrical charge than can then be transferred from point to point in the array, along the line, up to an end of this line; a memory zone having a second array with a same number of lines of cells and a transfer zone. The line of the second array is a looped line sequenced like the corresponding line of the first array, and at the same rate, and the transfer zone includes charge divider means receiving, at input, said charge transferred from point to point in the first array along the line and dividing said charge into two sub-charges with a pre-determined relative ratio; means to neutralize the first of these sub-charges; and means to add the second of these sub-charges to the charge received at output of the looped line and to reinject the resultant total charge into the input of the looped line so as to make it recirculate therein. The concomitant sequencing of the lines of the first array and of the second array is repeated in a plurality of cycles so as to bring about an increase, by the accumulation of the second successive sub-charges in the looped line, of the corresponding charge of the memory array. Thus, by the resulting second integration, the dynamic range of the charge-coupled device is increased by a proportion corresponding to said pre-determined ratio of the two sub-charges, which is typically 40 dB (thus taking the dynamic range, for example, from 120 to 160 dB) for a ratio of 100:1.