Patent ID: 8730081

Claim:
A method comprising: applying a first set of analog data to a set of column analog-to-digital (A/D) converters of an image sensor having a pixel array that includes a set of columns of pixels that correspond to the set of column A/D converters, wherein applying the first set of the analog data comprises applying a first instance of a set of fixed voltages spanning a calibration voltage range to the set of the column A/D converters; generating a multiple slope voltage ramp; converting the first set of the analog data to a first set of digital data with the set of column A/D converters using the multiple slope voltage ramp; applying a second set of analog data to the set of column A/D converters, wherein applying the second set of the analog data comprises applying a second instance of the same set of fixed voltages spanning the calibration voltage range to the set of the column A/D converters; generating a single slope voltage ramp; and converting the second set of the analog data to a second set of digital data with the set of column A/D converters using the single slope voltage ramp.