CMOS image sensor readout employing in-pixel transistor current sensing
First Claim
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1. An active pixel sensor image sensor comprising:
- a plurality of sensing elements for a plurality of pixels, the plurality of sensing elements being organized into a plurality of rows;
a row bus for each of the rows of sensing elements;
an in-pixel readout transistor for each of the sensing elements;
a current-sensing circuit for each of the rows, the current-sensing circuit being external to the pixels and connected to the in-pixel readout transistor of each of the pixels in said each of the rows by the row bus, for sensing a current through the in-pixel readout transistor; and
a feedback circuit for each of the rows, external to the pixels, for supplying a feedback to charge a read-line parasitic capacitance of the row bus in accordance with the current sensed by the current-sensing circuit.
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Abstract
In an image sensor, the current through the in-pixel readout transistor is sensed by a circuit that is external to the pixel, and according to the measured current value a feedback current is supplied to charge the read-line parasitic capacitance. The feedback current is supplied by a circuit that also is external to the pixel area. The amplifier structure is reconfigurable so that it can be used both to read out and to reset the pixel.
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12 Claims
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1. An active pixel sensor image sensor comprising:
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a plurality of sensing elements for a plurality of pixels, the plurality of sensing elements being organized into a plurality of rows; a row bus for each of the rows of sensing elements; an in-pixel readout transistor for each of the sensing elements; a current-sensing circuit for each of the rows, the current-sensing circuit being external to the pixels and connected to the in-pixel readout transistor of each of the pixels in said each of the rows by the row bus, for sensing a current through the in-pixel readout transistor; and a feedback circuit for each of the rows, external to the pixels, for supplying a feedback to charge a read-line parasitic capacitance of the row bus in accordance with the current sensed by the current-sensing circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification