Patent ID: 8379122

Claim:
A solid-state image-pickup device comprising: a plurality of pixels, each converting an incident-light quantity into a respective electrical signal and a plurality of analog-to-digital converters each of which converts an analog signal obtained from a respective one of the pixels into a digital signal, wherein, each analog-to-digital converter includes (a) an output having a plurality of bits; and (b) a plurality of comparators including first and second comparators, wherein each of the comparators compares a respective one of a plurality of reference voltages changing over time to the analog signal from the same one of the pixels, and at least first and second reference voltages are transmitted to respective ones of the comparators, the first comparator is associated with a first portion of the plurality of bits of the output, and the second comparator is associated with a second portion of the plurality of bits of the output, each of the first and second portions being greater than 1 bit, and the analog signal is read from the pixel two times for each row, and a difference between a result of first reading and a result of second reading is calculated.