Current mode pixel and readout circuit

A device comprising a pixel, a current source, a sample and buffer circuit and a current memory circuit;

• wherein during a first readout phase the current source is configured to drain a first fixed current from an output node of the pixel, wherein the sample and buffer circuit is configured to sample a voltage of the output node of the pixel to provide a sampled voltage, and the current source is disconnected from the sample and buffer circuit and from the output node of the pixel;
• wherein the pixel is configured to transfer, between the first readout phase and a second readout phase, toward an output transistor of the pixel, a charge that is indicative of radiation sensed by the a sensing element of the pixel;
• wherein the output transistor of the pixel is coupled to the output node of the pixel;
• wherein during a second readout phase the pixel is configured to provide to the output node a pixel current that is responsive to the charge, the current source is configured to drain a second fixed current from the output node of the pixel, the sample and buffer circuit is configured to provide to the output node of the pixel the sampled voltage, and the current memory is configured to provide, via a feedback path, a feedback current to the output node of the pixel and to store a current memory voltage that once provided to an output transistor of the current memory causes the current memory to output the feedback current;
• wherein the feedback current substantially equals a difference between the second fixed current and the pixel current;
• wherein during a third readout phase the current memory is configured to output the feedback current to a digital to analog converter.