Operating method of pixel circuit adopting optically sensitive material to suppress dark current
AssigneePixart Imaging Inc.
InventorKazuya Yonemoto
Life of this patent
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Abstract
There is provided a pixel circuit including an optically sensitive material (OSM) layer and a readout circuit. The OSM layer is arranged upon the readout circuit, and used to sense light energy to generate signal charges to be integrated in a floating diffusion. The readout circuit includes a source follower for amplifying a voltage on the floating diffusion within a readout interval, and the voltage on the floating diffusion is not changed by an external voltage pulse within the readout interval.
Claims20
An operating method of a pixel circuit, the pixel circuit comprising a floating diffusion (FD) node, an optically sensitive material (OSM) layer, a reset transistor having a source as the FD node, a readout transistor connected to the FD node and a row selection transistor connected to the readout transistor, the reset transistor being arranged within a P-well substrate of the pixel circuit, and the readout transistor and the row selection transistor being arranged within an N-well region in the P-well substrate, the operating method comprising:
- providing an exposure control signal to the OSM layer to integrate charges into the FD node;
- providing a row selection signal to the row selection transistor to cause the charges integrated in the FD node to form a first voltage drop on an output voltage via the readout transistor;
- providing a reset control signal to the reset transistor to cause a reset voltage to form a second voltage drop on the output voltage via the readout transistor,
- wherein the reset voltage is arranged between +1 volt and −0.5 volt relative to a voltage of the P-well substrate to cause the readout transistor to operate within a linear region thereof.
An operating method of a pixel circuit, the pixel circuit comprising a floating diffusion (FD) node, an optically sensitive material (OSM) layer, a reset transistor having a source as the FD node, a readout transistor connected to the FD node and a row selection transistor connected to the readout transistor, the readout transistor and the row selection transistor being arranged within a P-well substrate of the pixel circuit, and the reset transistor being arranged within an N-well region in the P-well substrate, the operating method comprising:
- providing an exposure control signal to the OSM layer to integrate charges into the FD node;
- providing a row selection signal to the row selection transistor to cause the charges integrated in the FD node to form a first voltage rise on an output voltage via the readout transistor;
- providing a reset control signal to the reset transistor to cause a reset voltage to form a second voltage rise on the output voltage via the readout transistor,
- wherein the reset voltage is arranged between +0.5 volt and −1 volt relative to a voltage source coupled to a drain of the readout transistor to cause the readout transistor to operate within a linear region thereof.
An operating method of a pixel circuit, the pixel circuit comprising a floating diffusion (FD) node, an optically sensitive material (OSM) layer, an IGZO transistor having a source as the FD node, a readout transistor connected to the FD node and a row selection transistor connected to the readout transistor, the operating method comprising:
- providing an exposure control signal to the OSM layer to integrate charges into the FD node;
- providing a row selection signal to the row selection transistor to cause the charges integrated in the FD node to form a voltage rise on an output voltage via the readout transistor;
- providing a reset control signal to the IGZO transistor to cause a reset voltage to form a voltage drop on the output voltage via the readout transistor,
- wherein the reset voltage is arranged between +0.5 volt and −1 volt relative to a voltage source coupled to a drain of the readout transistor to cause the readout transistor to operate within an operating voltage region thereof.
Dependencies are inferred from the claim text.