Active pixel with precharging circuit
First Claim
1. An active pixel comprising:
- a sensor circuit to generate a signal in response to electromagnetic radiation received on a photodetector included therein;
a sample and hold (S/H) stage coupled to an output of the sensor circuit to read-out and store the signal, the S/H stage including a sample switching-element to couple the signal from the sensor circuit to a capacitor element in the S/H stage to store the signal;
a buffer/multiplexer circuit including a row-select switching-element coupled to an output node of the capacitor element to couple the signal to a column; and
a precharge circuit including a precharge switching-element coupled between the output node of the capacitor element and the column to precharge the capacitor element to a precharge voltage applied to the column when the S/H stage is not reading-out the signal from the sensor circuit.
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Accused Products
Abstract
An active pixel including a precharge circuit for a sample and hold (S/H) stage and methods of operating the same are provided. In addition to the precharge circuit and S/H stage, the pixel may include a sensor circuit to generate a signal in response to electromagnetic radiation received on a photodetector included therein, and a multiplexer circuit. The S/H stage may include a switching-element to couple the signal from the sensor circuit to a capacitor element in the S/H stage to read-out and store the signal. The multiplexer circuit may include a switching-element coupled to an output node of the capacitor element to couple the signal to a column. The precharge circuit may include a switching-element coupled between the output node of the capacitor element and the column to precharge the capacitor element to a fixed voltage applied to the column when the S/H stage is not reading-out the signal.
135 Citations
20 Claims
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1. An active pixel comprising:
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a sensor circuit to generate a signal in response to electromagnetic radiation received on a photodetector included therein; a sample and hold (S/H) stage coupled to an output of the sensor circuit to read-out and store the signal, the S/H stage including a sample switching-element to couple the signal from the sensor circuit to a capacitor element in the S/H stage to store the signal; a buffer/multiplexer circuit including a row-select switching-element coupled to an output node of the capacitor element to couple the signal to a column; and a precharge circuit including a precharge switching-element coupled between the output node of the capacitor element and the column to precharge the capacitor element to a precharge voltage applied to the column when the S/H stage is not reading-out the signal from the sensor circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An image sensor including an array of a plurality of active pixels, at least one of the plurality of active pixels comprising:
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a sensor circuit to generate a signal in response to electromagnetic radiation received on a photodetector included therein; a sample and hold (S/H) stage coupled to an output of the sensor circuit to read-out and store the signal, the S/H stage including a sample switching-element to couple the signal from the sensor circuit to a capacitor element in the S/H stage to store the signal; a buffer/multiplexer circuit including a row-select switching-element coupled to an output node of the capacitor element to couple the signal to a column in the array; and a precharge circuit including a precharge switching-element coupled between the output node of the capacitor element and the column to precharge the capacitor element to a column precharge voltage applied to the column when the S/H stage is not reading-out the signal therefrom. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A method for precharging a capacitor element in an in-pixel sample and hold (S/H) stage of an active pixel, the method comprising:
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electrically decoupling a sensor circuit in the active pixel from the S/H stage; electrically coupling an output node of the capacitor element to a column through a precharge transistor, the precharge transistor having a drain coupled to the output node of the capacitor element and a source coupled to the column; and applying a precharge voltage to the column to precharge the capacitor element and the column. - View Dependent Claims (17, 18, 19, 20)
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Specification