High dynamic range pixel

摘要

A high dynamic range pixel (2) includes a photosensor device (4) for detecting incident light, said photosensor having a photosensor output (14) for a photosensor signal Vp that represents a time integral of the detected light intensity over an integration period. A transistor disconnect switch (8) has a first switch input (15) that is connected to the photosensor output (14), a second switch input (17) that is connected to receive a time-dependent reference signal Vref, and a switch output (16) for a switch output signal Vs that is switchably connected to the first switch input. The disconnect switch (8) is constructed and arranged to disconnect the switch output (16) from the first switch input (15) at a capture moment that depends on the relative values of input signals at the first and second switch inputs (15,18). A readout circuit (10) is connected to the switch output (16) and arranged to capture the switch output signal Vs at the capture moment and provide an output signal Vout that is related to the switch output signal Vs. The first switch input (15) is connected additionally to an input (29) for a time-dependent applied signal Vapp, such that the input signal at the first switch input (15) is the sum of the photosensor signal Vp and the applied signal Vapp.