| 摘要 |
A pixel sensor cell of improved dynamic range comprises a coupling transistor that couples a capacitor device to a photosensing region (e.g., photodiode) of the pixel cell, the photodiode being coupled to a transfer gate and one terminal of the coupling transistor. In operation, the additional capacitance is coupled to the pixel cell photodiode when the voltage on the photodiode is drawn down to the substrate potential. Thus, the added capacitance is only connected to the imager cell when the cell is nearing its charge capacity. Otherwise, the cell has a low capacitance and low leakage. In an additional embodiment, a terminal of the capacitor is coupled to a “pulsed” supply voltage signal that enables substantially full depletion of stored charge from the capacitor to the photosensing region during a read out operation of the pixel sensor cell. In various embodiments, the locations of the added capacitance and photodiode may be interchanged with respect to the coupling transistor. In addition, the added capacitor of the pixel sensor cell allows for a global shutter operation.
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