Circuit architecture of a pixel for detecting and calculating the number of photons, characterized in that it comprises: - a photodiode having a first contact terminal connected to the first contact terminal of first electronic interruption means and the second contact terminal connected to a first input pin of said pixel so as to receive an input bias voltage (V S); - said first electronic interruption means having the switch over control terminal connected to a second input pin so as to receive a first switch over control signal (SDRV) and the second contact terminal connected to a third input pin so as to receive a reference voltage value; - second electronic interruption means having the first contact terminal connected to a first charge accumulation element, the second contact terminal connected to said first contact terminal of said photodiode and the switch over control terminal connected to a fourth input pin so as to receive a second switch over control signal; - third electronic interruption means having the first contact terminal connected to a fifth input pin so as to receive a propagation signal and the switch over control terminal connected to said first charge accumulation element so as to receive the voltage value (V LATCH) present on said first charge accumulation element as a switch over control signal; - fourth electronic interruption means having the first contact terminal connected to a third charge accumulation element and to an output pin for withdrawing the voltage value (V CNT) present on said third charge accumulation element, the second contact terminal connected to the first contact terminal of fifth electronic interruption means and to a second charge accumulation element and the switch over control terminal connected to the second contact terminal of said third electronic interruption means so as to receive a voltage value (V PULSE) at the output of said second contact terminal as a switch over control signal; - said fifth electronic interruption means having the second contact terminal connected to a sixth input pin so as to receive a reference voltage value (V BIAS) and the switch over control terminal connected to a seventh input pin so as to receive a third switch over control input signal. - a photodiode having a first contact terminal connected to the first contact terminal of first electronic interruption means and the second contact terminal connected to a first input pin of said pixel so as to receive an input bias voltage (V S); - said first electronic interruption means having the switch over control terminal connected to a second input pin so as to receive a first switch over control signal (SDRV) and the second contact terminal connected to a third input pin so as to receive a reference voltage value; - second electronic interruption means having the first contact terminal connected to a first charge accumulation element, the second contact terminal connected to said first contact terminal of said photodiode and the switch over control terminal connected to a fourth input pin so as to receive a second switch over control signal; - third electronic interruption means having the first contact terminal connected to a fifth input pin so as to receive a propagation signal and the switch over control terminal connected to said first charge accumulation element so as to receive the voltage value (V LATCH) present on said first charge accumulation element as a switch over control signal; - fourth electronic interruption means having the first contact terminal connected to a third charge accumulation element and to an output pin for withdrawing the voltage value (V CNT) present on said third charge accumulation element, the second contact terminal connected to the first contact terminal of fifth electronic interruption means and to a second charge accumulation element and the switch over control terminal connected to the second contact terminal of said third electronic interruption means so as to receive a voltage value (V PULSE) at the output of said second contact terminal as a switch over control signal; - said fifth electronic interruption means having the second contact terminal connected to a sixth input pin so as to receive a reference voltage value (V BIAS) and the switch over control terminal connected to a seventh input pin so as to receive a third switch over control input signal.