Monolithically integrated two-dimensional image sensor with a difference forming stage

摘要

A monolithically integrated two-dimensional image sensor having an array of sensor elements disposed in rows and columns connected by respective row and column lines. A first readout of the sensor elements is undertaken and a charge packet representing the signal is formed by an oppositely doped semiconductor region connected to the respective column lines which charge packet contains charge carriers generated as a result of incident radiation as well as noise signals. A second readout of the sensor elements is undertaken for a short duration so that the charge packet generated as a result of the second readout represents only noise signals. A difference-forming stage connected to the image sensor has a storage capacitor associated with each column line for subsequently storing the two signals such that the voltage at the capacitor is displaced from a reference potential in an amount representing the difference between the two signals which thus provides a signal to a serial output device such as a charge transfer device which represents only charge carriers generated by incident radiation and is substantially noise-free. The capacitors are connected to a reset device for preparing the difference-forming stage for the next readout sequence.