Image sensors with reduced noise
AssigneeSemiconductor Components Industries, LLC
InventorRichard Scott Johnson
Life of this patent
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Abstract
An image senor may include an array of pixels controlled by row control circuitry. Each pixel may include a photodiode for generating image signals and a charge storage structure coupled to a floating diffusion region and configured to generate and store parasitic light noise level signals. The image signals and the parasitic light noise level signals may be read out in the same readout cycle using shared or separate readout circuitry. Processing circuitry may selectively process the image signals based on the parasitic light noise level signals to generate image signals with reduced noise.
Claims18
An image sensor, comprising:
- an array of image pixels, wherein an image pixel in the array includes:
- a photosensitive element coupled to a floating diffusion region via a first path and operable to generate an image level signal, and
- a charge storage structure coupled to the floating diffusion region via a second path and operable to generate a parasitic light noise level signal;
- control circuitry operable to perform a readout operation on the image level signal and a readout operation on the parasitic light noise level signal;
- and
- processing circuitry operable to perform a subtraction operation based on the image level signal and the parasitic light noise level signal, wherein the processing circuitry is operable to perform the subtraction operation based on whether the parasitic light noise level signal is greater than a parasitic light noise signal threshold level or based on whether the image level signal is less than an image signal threshold level.
An image sensor, comprising:
- image pixels arranged in rows and columns, wherein each image pixel in the image pixels includes:
- a photosensitive element coupled to a floating diffusion region via a first path and configured to generate an image signal, and
- a charge storage structure coupled to the floating diffusion region via a second path and configured to generate a parasitic light signal that is representative of an amount of parasitic light noise at the floating diffusion region, wherein the first path is separate from the second path;
- and
- control circuitry configured to assert a first global control signal for the image pixels to begin generating the image signals, to control the image pixels to begin generating the parasitic light signals, and to perform readout operations in a row-by-row manner on sets of the image signals and the parasitic light signals, each set corresponding to the image signals and the parasitic light signals for a row of image pixels in the rows of image pixels.
An image sensor, comprising:
- an array of image pixels, wherein an image pixel in the array includes:
- a photosensitive element coupled to a floating diffusion region via a first path and operable to generate an image level signal, and
- a charge storage structure coupled to the floating diffusion region via a first transistor in a second path, operable to generate a parasitic light noise level signal in a parasitic light collection mode of operation, and operable to store a low conversion gain signal in a low conversion gain mode of operation, wherein the first path is separate from the second path, and the floating diffusion region is coupled to a power supply terminal via a second transistor;
- and
- readout circuitry operable to perform readout operations on the image level signal and the parasitic light noise level signal.
Dependencies are inferred from the claim text.