Image sensor with global shutter and in pixel storage transistor
First Claim
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1. An apparatus, comprising:
- a photodiode to accumulate an image charge;
a storage transistor to store the image charge;
a transfer transistor coupled between the photodiode and an input of the storage transistor to selectively transfer the image charge from the photodiode to the storage transistor;
an output transistor coupled to an output of the storage transistor to selectively transfer the image charge to a readout node;
a reset transistor coupled to the readout node;
a controller configured to apply a negative voltage to a gate of the storage transistor before activating the gate of the storage transistor to store the image charge;
a first select transistor coupled between the transfer transistor and the storage transistor to selectively transfer the image charge from the transfer transistor to the storage transistor; and
a second select transistor coupled between the readout node and a circuit node between the transfer transistor and the first select transistor, the controller further configured to reset the photodiode by activating the transfer transistor, the second select transistor, and the reset transistor.
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Abstract
An image sensor includes a photodiode to accumulate an image charge and a storage transistor to store the image charge. A transfer transistor is coupled between the photodiode and an input of the storage transistor to selectively transfer the image charge from the photodiode to the storage transistor. An output transistor is coupled to an output of the storage transistor to selectively transfer the image charge to a readout node and a reset transistor is coupled to the readout node. A controller is configured to apply a negative voltage to a gate of the storage transistor before activating the gate of the storage transistor to store the image charge.
73 Citations
16 Claims
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1. An apparatus, comprising:
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a photodiode to accumulate an image charge; a storage transistor to store the image charge; a transfer transistor coupled between the photodiode and an input of the storage transistor to selectively transfer the image charge from the photodiode to the storage transistor; an output transistor coupled to an output of the storage transistor to selectively transfer the image charge to a readout node; a reset transistor coupled to the readout node; a controller configured to apply a negative voltage to a gate of the storage transistor before activating the gate of the storage transistor to store the image charge; a first select transistor coupled between the transfer transistor and the storage transistor to selectively transfer the image charge from the transfer transistor to the storage transistor; and a second select transistor coupled between the readout node and a circuit node between the transfer transistor and the first select transistor, the controller further configured to reset the photodiode by activating the transfer transistor, the second select transistor, and the reset transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of operation of a pixel array, the method comprising:
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resetting a photodiode within each pixel of the pixel array prior to accumulating an image charge; negatively biasing a gate of a storage transistor within each of the pixels while the storage transistor is off and prior to temporarily storing the image charge within the storage transistor; asserting a global shutter signal to transfer the image charge accumulated by the photodiode of each pixel to the storage transistor of each pixel; and storing the image charge within the storage transistor of each pixel until the image charge is readout, wherein; a first portion of the storage transistors whose image charge has already been readout for a given imaging cycle are off while resetting the photodiode of each pixel, and a second portion of the storage transistors whose image charge has not already been readout for the given imaging cycle are on while resetting the photodiode of each pixel. - View Dependent Claims (9, 10, 11, 12, 13)
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14. An imaging system comprising:
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an array of imaging pixels having the imaging pixels arranged in rows and columns, wherein each imaging pixel includes; a photodiode to accumulate an image charge; a storage transistor to store the image charge; a transfer transistor coupled between the photodiode and the storage transistor; a first select transistor coupled between the transfer transistor and an input of the storage transistor; an output transistor coupled to an output of the storage transistor and a readout node; a reset transistor coupled between a voltage rail and the readout node; and a second select transistor coupled between the readout node and a circuit node between the transfer transistor and the first select transistor; and control circuitry coupled to the array of imaging pixels to control timing operation of the storage transistor, the transfer transistor, the first select transistor, the output transistor, the reset transistor, and the second select transistor, wherein the control circuit is configured to operate the transfer transistor to reset the photodiode through the second select transistor and to operate the transfer transistor as an image shutter to commence transfer of the image charge to the storage transistor through the first select transistor. - View Dependent Claims (15, 16)
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Specification