Patent ID: 8878830

Claim:
A method, comprising: operating a light sensor in a calibration mode by: disconnecting for the duration of the calibration mode a capacitor from a light-sensitive pixel including a photodiode having a first terminal and a second terminal; applying a photodiode reset voltage to charge said capacitor during a first time period; supplying a regulated reference analog current different from the photodiode reset voltage to discharge said capacitor during a second time period which subsequently follows the first time period; converting in said capacitor the regulated reference analog current over a calibration period of time to provide a calibration analog voltage; converting the calibration analog voltage to a digital calibration signal in an analog-to-digital converter circuit; and storing the calibration digital signal; and operating the light sensor in a light sensing mode by: applying said photodiode reset voltage to one of the first or second terminals of the light sensitive pixel; connecting said capacitor to one of the first or second terminals of the light sensitive pixel; converting in said connected capacitor an analog current generated at said one of the first or second terminals over an integrating period of time in response to received light to provide a pixel analog voltage; converting the pixel analog voltage to a digital pixel signal in said analog-to-digital converter circuit; and adjusting the digital pixel signal as a function of the digital calibration signal to generate a corrected pixel signal.