Photon counting pixel and method of operation thereof

A pixel array, comprising:

• a plurality of photosensitive pixels arranged in an array of a plurality of rows and a plurality of columns, wherein at least one photosensitive pixel of the plurality of photosensitive pixels comprises:
• a photodiode for generating photoelectrons;
• a first charge transfer gate;
• a charge storage and transfer electrode;
• a second charge transfer gate;
• a sensing node;
• a reset gate coupled to the charge storage and transfer electrode;
• a drain coupled to the reset gate;
• and
• an amplifier coupled to the sensing node;
• wherein the first charge transfer gate is controllable via a first control signal from a controller to couple the photodiode to the charge storage and transfer electrode so as to allow charge transfer;
• wherein the second charge transfer gate is controllable via a second control signal from the controller to couple the charge storage and transfer electrode to the sensing node so as to allow charge transfer;
• wherein the second charge transfer gate, the charge storage and transfer electrode, and the reset gate are controllable via third control signals from the controller to reset an electric potential of the sensing node;
• and
• wherein a respective photosensitive pixel is configured to transfer charge generated at a respective photodiode to a respective sensing node via a respective first charge transfer gate, a respective charge storage and transfer electrode, and a respective second charge transfer gate.

A pixel array, comprising:

• a plurality of groups of photosensitive pixels, wherein each group of photosensitive pixels comprises:
• a plurality of photodiodes for generating photoelectrons;
• a plurality of first charge transfer gates respectively associated with the plurality of photodiodes;
• a shared charge storage and transfer electrode;
• a shared second charge transfer gate;
• a shared sensing node;
• a shared reset gate coupled to the shared charge storage and transfer electrode;
• a shared drain coupled to the shared reset gate;
• and
• a shared amplifier coupled to the shared sensing node;
• wherein a respective first charge transfer gate is controllable via a first control signal from a controller to couple a respective associated photodiode to a respective shared charge storage and transfer electrode so as to allow charge transfer;
• wherein a respective shared second charge transfer gate is controllable via a second control signal from the controller to couple the respective shared charge storage and transfer electrode to a respective shared sensing node so as to allow charge transfer;
• wherein the respective shared second charge transfer gate, the respective shared charge storage and transfer electrode, and a respective shared reset gate are controllable via third control signals from the controller to reset an electric potential of the respective shared sensing node;
• and
• wherein a respective photosensitive pixel is configured to transfer charge generated at a respective plurality of photodiodes to the respective shared sensing node via a respective plurality of first charge transfer gates, the respective shared charge storage and transfer electrode, and the respective shared second charge transfer gate.