US Patent 10419701 Digital pixel image sensor

Disclosed herein are techniques for digital imaging. A digital pixel image sensor includes a digitizer in each pixel of a plurality of pixels, where the digitizer digitizes analog output signals from a photodiode of the pixel using a comparator, a global reference ramp signal, and a clock counter. In some embodiments, the comparator includes a pre-charging circuit, rather than a constant biasing circuit, to reduce the power consumption of each pixel. In some embodiments, each pixel includes a digital or analog correlated double sampling (CDS) circuit to reduce noise and provide a higher dynamic range.