Single photon counting image sensor and method

An image sensor device, comprising:

• a pixel circuit;
• a photodiode circuit of the pixel circuit to detect photons when a light is incident on the photodiode circuit;
• a counter circuit of the pixel circuit coupled to the photodiode circuit to count a number of photons detected when a light is incident on the avalanche photo diode;
• a memory circuit of the pixel circuit coupled to the counter circuit to store a time a count of the number of photons take to match a reference count of the number of photons;
• and
• a threshold multiplexer circuit of the pixel circuit to change the reference count of number of photons dynamically based on an output of a threshold selection circuit.

A camera on chip system, comprising:

• an image source;
• an array of pixel circuit to capture an image of the image source;
• a photodiode circuit inside each pixel circuit of the array of pixel circuit to detect photons when a light is incident on the photodiode circuit;
• a counter circuit of each pixel circuit of the array of pixel circuit, coupled to the photodiode circuit to count a number of photons detected when a light is incident on the avalanche photo diode;
• a memory circuit of each pixel circuit of the array of pixel circuit, coupled to the counter circuit to store a time a count of the number of photons take to match a reference count of the number of photons.