Image sensor

An image sensor, comprising:

• a photo detector circuit arranged to provide a detection quantity having a level that depends on an amount of light to which the photo detector circuit has been exposed during a photo detection time interval;
• a front-end circuit arranged to provide an output signal indicative of the amount of light in response to at least one input signal, among which is the detection quantity, the front-end circuit comprising a transistor having a threshold voltage that affects a relationship between the output signal and the level of the detection quantity, and a biasing node applying a biasing voltage to a semiconductor region that affects the threshold voltage of the transistor;
• a biasing circuit comprising a replica of the front-end circuit coupled to receive at least one defined input signal, among which is a substitute of the detection quantity having a defined level, the replica being arranged in a control loop adapted to control the biasing voltage that is applied to the biasing node in the replica, so that the replica provides a defined output signal, the biasing circuit being arranged to apply the biasing voltage to the biasing node in the front-end circuit.