Whether measuring charge or voltage, at some point the value needs to be converted to a digital output. With millions of pixels on a sensor, that requires a lot of ADC converters and potentially a lot of power. And for high speed applications, it all needs to be done quickly. We apply a number of techniques to speed the conversion ranging from multiple ADCs per column split across the top and bottom, to 3D stacking to add even more converters to each column of pixels to further speed conversion and increase frame rates.