Patent ID: 8094218

Claim:
An image sensor circuit comprising: at least one pixel cell for providing an output signal that varies between a maximum and a minimum magnitude in response to illumination of the at least one pixel cell during an exposure period; a first storage capacitor selectively coupled to the at least one pixel cell and storing a first image signal corresponding to a first output signal of the at least one pixel cell; a second storage capacitor selectively coupled to the at least one pixel cell and storing a second image signal corresponding to a second output signal of the at least one pixel cell; wherein the magnitude of the first output signal is equal or higher than the magnitude of the second output signal; a switching arrangement selectively and simultaneously connecting the first and second storage capacitors to respective differential inputs of a fully differential analog-to-digital converter via a differential bus bar; a first and a second offset signal source providing a first and a second offset signal having a magnitude between said minimum and maximum magnitudes, the first and second offset signals being selectively coupled to first and second lines of the differential bus bar upstream of the fully differential analog-to-digital converter, for offsetting the first and second image signals, respectively, at the corresponding inputs of the fully differential analog-to-digital converter, wherein the first and the second offset signals are selected to offset the first and second image signals in such a way that the full input range of the analog-to-digital converter is exploited.