Pixel Sensor Cell for CMOS Image Sensors with Enhanced Conversion Gain at High Dynamic Range Capability

A method for operating a pixel sensor cell, comprising:

• accumulating photoelectrons in a photodiode during a predetermined integration time, a first transfer transistor coupling the photodiode with an intermediate node and configured to be controlled by a first control signal;
• in a first phase, coupling an intermediate node with a sense node by means of a second transfer transistor and providing a charge threshold for accumulated photoelectrons so that only excess photoelectrons are allowed to pass to the intermediate node, wherein the potential generated by the excess photoelectrons is read out as an HDS sampling output signal;
• in a second phase, controlling the second transfer transistor to set a threshold of the second transfer transistor to a potential where the second transfer transistor isolates the intermediate node and the sense node and which is substantially equal or higher than the potential of the intermediate node, coupling the intermediate node with the sense node and reading out the potential on the sense node as an LLS sampling output signal.