Method for obtaining a high dynamic range read-out signal of a CMOS-based pixel structure and such CMOS-based pixel structure

摘要

A method is disclosed for obtaining a read-out signal of a MOS- based pixel structure having at least a photosensitive element with an output node and a memory element with a first switch therebetween. The method comprises the steps of while acquiring charge carriers on said output node of said photosensitive element, said charge carriers being converted from electromagnetic radiation on the photosensitive element, after a first time period creating a first signal, and after a second time period, creating a second signal, said read-out signal being a combination of at least said first and said second signals.P P According to the present invention, there is no limitation to the amount of collected charges in none of the integrated periods. The signal collected during the first period is memorized by a switch which shortly opens and closes between the period. The switch is thus in the same state in both period of time. After a second period, there are thus two charge packets, each obtained during a different time. In order to read- out, these two charge packets are then combined into one reading. This combination is known either by adding or subtracting this charge packets, e.g., by adding or subtracting them in the circuitry external to the sensor.