Digital pixel with extended dynamic range

An analog-to-digital converter (ADC) comprising:

• a comparator;
• a sampling capacitor having a first plate coupled with an output of a charge sensing unit and a second plate being coupled with an input of the comparator;
• and
• a controller configured to:
• at a first time, set a first voltage across the sampling capacitor based on an output voltage of the charge sensing unit at the first time;
• reset the charge sensing unit to set the first plate at a second voltage and to set the second plate at a third voltage based on the first voltage and the second voltage;
• compare, using the comparator, the third voltage against one or more thresholds;
• and
• generate, based on the comparison result, a quantization result of the output voltage of the charge sensing unit at the first time.

A method comprising:

• enabling a photodiode to generate charge responsive to incident light within an integration period;
• controlling a charge sensing unit to generate an output voltage based on a quantity of the charge generated by the photodiode within the integration period;
• after the integration period, and based on the output voltage of the charge sensing unit, setting a first voltage across a sampling capacitor, wherein a first plate of the sampling capacitor is coupled with an output of the charge sensing unit and a second plate of the sampling capacitor is coupled with an input of an comparator;
• resetting the charge sensing unit to set the first plate at a second voltage and to set the second plate at a third voltage based on the first voltage and the second voltage;
• comparing, using the comparator, the third voltage against one or more thresholds;
• and
• generating, based on the comparison result, a quantization result of the output voltage to represent an intensity of the incident light received by the photodiode within the integration period.