Patent ID: 7768562

Claim:
A readout circuit for an imager, said readout circuit comprising: a circuit for receiving, during a conversion period, analog output signals from a plurality of pixels in a plurality of rows of a common column of a pixel array and for digitally converting said signals received during said conversion period in a manner which provides an accumulated digital output signal representing the combination of the analog output signals from said plurality of pixels, wherein said circuit for receiving and converting comprises: a sample and hold circuit for receiving said analog output signals from said plurality of pixels; a counter for storing said accumulated digital output signal; and a digital converter for providing count values to said counter for each of said received analog output signals, wherein said digital converter has a total conversion period during which said counter accumulates count values, and each of said analog output signals from said plurality of pixels are converted for a respective portion of said total conversion period, said counter accumulating count values for each portion of said total conversion period.