Imaging devices and methods for charge transfer
First Claim
Patent Images
1. A pixel circuit comprising:
- at least one pixel including a photosensor and a transfer transistor;
a charge storage node configured to be electrically connected to said photosensor when said transfer transistor is activated;
an amplifier having an input node and an output node, the input node electrically connected to said charge storage node; and
a feedback loop electrically connected between said input node and said output node of said amplifier, said feedback loop comprising a capacitance element and a reset transistor electrically connected in parallel to said capacitance element during operation of said pixel, wherein said reset transistor is configured to receive a reset control signal and said transfer transistor is configured to receive a transfer control signal from a control circuit, and wherein said control circuit is configured to deactivate said reset transistor and activate said transfer transistor to form a capacitance divider between said capacitance element and said photosensor.
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Accused Products
Abstract
A pixel circuit having improved charge transfer including an amplifier having an input node electrically connected to a charge storage node of the pixel circuit, and a negative feedback control loop having a capacitance element electrically connected between the input node and an output node of said amplifier.
16 Citations
27 Claims
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1. A pixel circuit comprising:
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at least one pixel including a photosensor and a transfer transistor; a charge storage node configured to be electrically connected to said photosensor when said transfer transistor is activated; an amplifier having an input node and an output node, the input node electrically connected to said charge storage node; and a feedback loop electrically connected between said input node and said output node of said amplifier, said feedback loop comprising a capacitance element and a reset transistor electrically connected in parallel to said capacitance element during operation of said pixel, wherein said reset transistor is configured to receive a reset control signal and said transfer transistor is configured to receive a transfer control signal from a control circuit, and wherein said control circuit is configured to deactivate said reset transistor and activate said transfer transistor to form a capacitance divider between said capacitance element and said photosensor. - View Dependent Claims (2)
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3. A pixel circuit comprising:
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at least one pixel including a photosensor and a transfer transistor; a charge storage node configured to be electrically connected to said photosensor when said transfer transistor is activated; an amplifier having an input node and an output node, the input node electrically connected to said charge storage node; a capacitive element electrically connected between said input node and said output node of said amplifier; and a reset transistor electrically connected in parallel to said capacitance element, wherein, during an integration period of said pixel, said capacitive element and said reset transistor form a negative feedback control loop with said amplifier that fixes a voltage on said charge storage node, wherein said amplifier is a common-source amplifier comprising a transistor with a gate electrically connected to said charge storage node, and a drain connected to a column current sink and said negative feedback control loop. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A pixel circuit comprising:
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at least one pixel including a photosensor and a transfer transistor; a charge storage node configured to be electrically connected to said photosensor when said transfer transistor is activated; an amplifier having an input node and an output node, the input node electrically connected to said charge storage node; and a feedback loop electrically connected between said input node and said output node of said amplifier, said feedback loop comprising a capacitance element and a reset transistor electrically connected in parallel to said capacitance element during operation of said pixel, wherein said amplifier comprises a common source amplifier comprising a transistor with a gate connected to said charge storage node, a source connected to a ground potential, and a drain connected to said capacitance element, wherein said common source amplifier is biased by a current sink, said pixel circuit further comprising a row select transistor electrically connected in said feedback loop between said capacitance element and said reset transistor, and wherein a control circuit is configured to deactivate said reset transistor and activate said transfer transistor to form a capacitance divider between said capacitance element and said photosensor.
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14. A method of operating a pixel cell having a pixel circuit, said method comprising:
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resetting said pixel circuit by activating a reset transistor of said pixel circuit, said pixel circuit further comprising at least one photosensor, a charge storage node, an amplifier having an input connected to said charge storage node, and a capacitance element in a feedback loop of said amplifier; and amplifying a pixel signal of said pixel circuit by; deactivating said reset transistor, electrically connecting said at least one photosensor to said capacitance element and said floating diffusion node by activating said transfer transistor to form a capacitance divider between said at least one photosensor and said capacitance element, and amplifying a signal provided at an input of said amplifier to produce a pixel signal. - View Dependent Claims (15, 16, 17, 18)
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19. An imager comprising:
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a pixel array having a plurality of pixels, each of said pixels including at least one pair of a transfer transistor and a photosensor, said pixel array comprising; a circuit configured to output a pixel signal from at least one of said pixels, said circuit comprising; a charge storage node connected to said transfer transistor of said pixel; an amplifier having an input node and an output node, wherein the input node is electrically connected to said charge storage node; a capacitive element electrically connected between said input node and said output node of said amplifier; and a reset transistor electrically connected in parallel to said capacitance element, wherein, during an integration period of said pixel, said capacitive element and said reset transistor form a negative feedback control loop with said amplifier that fixes a voltage on said charge storage node, wherein said amplifier is a common-source amplifier comprising a transistor with a gate electrically connected to said charge storage node, and a drain connected to a column current sink and said negative feedback control loop; and sample-and-hold circuitry for sampling a reset voltage and an output voltage from said circuit. - View Dependent Claims (20, 26, 27)
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21. An imager comprising:
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a pixel array having a plurality of pixels, each of said pixels including at least one pair of a transfer transistor and a photosensor, said pixel array comprising; a circuit configured to output a pixel signal from at least one of said pixels, said circuit comprising; a charge storage node connected to said transfer transistor of said pixel; an amplifier having an input node and an output node, wherein the input node is electrically connected to said charge storage node; and a feedback loop electrically connected between said input node and said output node of said amplifier, said feedback loop comprising a capacitance element and a reset transistor electrically connected in parallel to said capacitance element during operation of said pixel; sample-and-hold circuitry for sampling a reset voltage and an output voltage from said circuit; and a control circuit configured to deactivate said reset transistor and activate at least one transfer transistor to form a capacitance divider between said capacitance element and said photosensor corresponding to said at least one activated transfer transistor. - View Dependent Claims (22, 23, 24, 25)
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Specification