Ground referenced pixel reset
First Claim
Patent Images
1. An image capture system comprising, a pixel comprising:
- a first FET having a gate terminal coupled to a reset line for providing a reset signal, a drain terminal coupled to a supply voltage, and a source terminal; and
a photodetector coupled between a first ground and the source terminal of the first FET;
a first switching device selectively coupled to the reset line; and
a reference voltage source coupled between a second ground and the reset line via the first switching device, wherein the reference voltage source generates a ground referenced reset voltage and the first and second grounds have the same potential.
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Abstract
A ground referenced pixel reset circuit is disclosed. The ground referenced pixel reset circuit supplies a pixel with a reset signal such that when the reset signal is asserted high, the reset signal is at a ground referenced reset voltage independent from a supply voltage. The pixel includes a photosensor, such as a photodiode, that is coupled to a ground having a same potential as the ground of the reference voltage supply. In this manner, noise caused by fluctuations in the supply voltage is reduced.
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Citations
20 Claims
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1. An image capture system comprising,
a pixel comprising: -
a first FET having a gate terminal coupled to a reset line for providing a reset signal, a drain terminal coupled to a supply voltage, and a source terminal; and
a photodetector coupled between a first ground and the source terminal of the first FET;
a first switching device selectively coupled to the reset line; and
a reference voltage source coupled between a second ground and the reset line via the first switching device, wherein the reference voltage source generates a ground referenced reset voltage and the first and second grounds have the same potential. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus comprising:
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a pixel having a photodetector coupled to a reset transistor, the reset transistor being configured to receive a reset signal;
a reference voltage source coupled to the reset transistor for providing the reset signal to the reset transistor; and
a supply voltage source coupled to the reset transistor for resetting the photodetector between exposure intervals. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A method comprising:
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providing a first reset signal to a pixel, the first reset signal being equal to a reference voltage;
resetting the pixel in response to the first reset signal using a supply voltage, the supply voltage being different from the reference voltage;
reading a first voltage value generated at the pixel following a light exposure interval;
providing a second reset signal to the pixel, the second reset signal being equal to the reference voltage;
reading a second voltage value from the pixel; and
generating a pixel value using the first and the second voltage values. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification