Patent ID: 8643132

Claim:
An imaging sensor pixel comprising: a floating diffusion (FD) region; a photosensitive element to acquire an image charge; a single metal oxide-semiconductor (MOS) capacitor, comprising a plurality of MOS capacitance regions each having a minimum capacitance value, coupled to the FD region to increase the capacitance of the FD region, wherein each of the MOS capacitance regions comprises a different dopant level and a different threshold voltage value based on its dopant level, and the plurality of MOS capacitance regions are arranged in the single MOS capacitor based on an ascending order of each regions' threshold voltage value, and a dopant concentration of the plurality of MOS capacitance regions increases from a dopant region closest to the FD region to a dopant region closest to a shallow trench isolation region, and the plurality of MOS capacitance regions are formed in a diffusion well having a dopant type same as the dopant type of the plurality of MOS capacitance regions; and a transfer gate to transfer the image charge from the photosensitive element to the FD region for controlling a capacitance of the single MOS capacitor by causing one or more of the plurality of MOS capacitance regions to have a capacitance value greater than its minimum capacitance value when the image charge transferred from the photosensitive element to the FD region exceeds the respective MOS capacitance region's threshold voltage value.