Patent ID: 8232512
Filing Date: 2012-07-31
Classification: H03F

Abstract:
1. An apparatus configured to integrate a quantity of light, comprising: a photosensor; an integration capacitor; a transfer ampler comprising (i) an input coupled to receive a voltage determined by the integration capacitor, and (ii) an output; a first switch configured to pull the integration capacitor to a precharge voltage; a second switch configured to couple the integration capacitor to the photosensor, and to discharge the integration capacitor in proportion to a quantity of light that is incident on the photosensor; and a controller configured to (i) generate one or more pulse-width-modulated (PWM) drive signals for controlling a light source configured to produce the light incident on the photosensor, and (ii) synchronize opening and closing of the first and second switches with an integer multiple of a PWM period of the PWM drive signals, wherein the apparatus is disposed on a single integrated circuit.