Meta Platforms Technologies, LLC

Facebook Technologies, LLC

Tsung-Hsun Tsai

Xinqiao Liu

Song Chen

Andrew Samuel Berkovich

Lyle David Bainbridge

Wei Gao

Lu Jie

Some examples described herein include a noise-reduction circuit for an image sensor. The noise-reduction circuit can include a reference frame generator configured to generate a reference frame based on a set of image frames received from an image sensor during a calibration phase. The noise-reduction circuit can also include a memory coupled to the reference frame generator. The memory can receive the reference frame from the reference frame generator and store the reference frame for subsequent use during a noise-reduction phase. The noise-reduction circuit can further include a processor coupled to the memory. The processor can retrieve the reference frame from the memory and use the reference frame to reduce noise in an image frame received from the image sensor during the noise-reduction phase.

Noise-reduction circuit for an image sensor

One example described herein includes the digital image sensor having a pixel cell with a photodiode and a quantizer circuit coupled to the pixel cell. The quantizer circuit includes a charge storage device that generates a voltage based on electric charge from the photodiode. The quantizer circuit also includes a single-input comparator that can switch from a first output state to a second output state in response to a ramp signal provided by a ramp generator. The quantizer circuit further includes a memory switch that can cause a counter value from a digital counter to be stored in a digital memory in response to the single-input comparator switching from the first output state to the second output state. The counter value can serve as a digital pixel value associated with the pixel cell.

Digital image sensor using a single-input comparator based quantizer

In some examples, a sensor apparatus comprises: a pixel cell configured to generate a voltages, the pixel cell including a photodiode configured to generate charge in response to incoming light, and a charge storage device to convert the charge to a voltage; an integrated circuit configured to: determine a first captured voltage converted by the charge storage device during a first time period; compare the first captured voltage to a threshold voltage value; and in response to determining that the first captured voltage meets or exceeds the threshold voltage value: determine first time data corresponding to the first time period; and prevent the charge storage device from further generating a charge; and an analog-to-digital converter (ADC) configured to generate a digital pixel value based on the first captured voltage, and a memory to store the digital pixel value and the first time data.

Digital pixel sensor having reduced quantization operation

In one example, an apparatus comprises: a photodiode to generate a charge in response to light within an exposure period having a first duration; a charge sensing unit to accumulate at least a part of the charge within the exposure period; a quantizer; and a controller to: determine, using the quantizer and within a measurement period having a second duration, whether a first quantity of the at least a part of the charge accumulated at the charge sensing unit exceeds a threshold, and a time it takes for the first quantity to exceed the threshold, wherein the first duration and the second duration are individually programmable; and based on whether the first quantity exceeds the threshold, output a first value representing the time or a second value representing a second quantity of the charge generated by the photodiode within the exposure period to represent an intensity of the light.

Non-linear quantization at pixel sensor

In one example, an apparatus comprises: a photodiode configured to generate a charge in response to light within an exposure period, a charge sensing unit configured to accumulate at least a part of the charge as an overflow charge, a quantizer, and a controller configured to: within a first time within the exposure period, control the quantizer to perform a first quantization operation to quantize the overflow charge accumulated at the charge sensing unit to generate a first measurement output; within a second time after the first time, and within the exposure period, control the quantizer to perform a second quantization operation to quantize the overflow charge accumulated at the charge sensing unit to generate a second measurement output; and generate a digital output to represent an intensity of the light based on at least one of the first measurement output or the second measurement output.

Digital pixel sensor having extended dynamic range

In one example, an apparatus comprises an array of pixel cells, each pixel cell including: a photodiode to generate a charge in response to incident light, a charge sensing unit configured to generate a voltage based on the charge, a quantizer configured to generate a digital output based on quantizing the voltage, and an in-pixel memory configured to store the digital output. The apparatus further includes a bus interface, an off-array frame memory, and a frame memory controller configured to: control the frame memory to receive, via the set of parallel interconnects, the digital outputs from the in-pixel memory of each pixel cell of the array of pixel cells; store the digital outputs in the frame memory; fetch the digital outputs from the frame memory; and transmit the digital outputs to a host device via the bus interface.

Pixel sensor having hierarchical memory

An apparatus comprises a first photodiode, a second photodiode, a quantizer, a memory, and a controller configured to: set a first exposure period in which the first photodiode generates a first charge; set a second exposure period in which the second photodiode generates a second charge, the second exposure period being set based on the first exposure period and at least one of: a first time associated with a read out operation of the memory to a second apparatus, or a second time associated with a quantization operation by the quantizer; perform, using the quantizer, the first quantization operation of the first charge to generate a first digital output; and perform, using the quantizer, a second quantization operation of the second charge to generate a second digital output.

Pixel sensor having shared readout structure

Methods and systems for quantizing a physical quantity, such as light, are provided. In one example, an apparatus comprises an analog-to-digital (A/D) converter configured to generate raw digital outputs based on performing at least one of: (1) a first quantization operation to quantize a physical stimulus within a first intensity range based on a first A/D conversion relationship, or (2) a second quantization operation to quantize the physical stimulus within a second intensity range based on a second A/D conversion relationship; and a raw output conversion circuit configured generate a refined digital output based on a raw digital output obtained from the A/D converter and at least one predetermined conversion parameter. The at least one conversion parameter compensates for a discontinuity between the first A/D conversion relationship and the second A/D conversion relationship.

Image sensor post processing

An apparatus comprises a first photodiode, a second photodiode, a charge sensing unit, a quantizer, a memory, and a controller configured to: set a first exposure period in which the first photodiode generates a first charge; set a second exposure period in which the second photodiode generates a second charge, the second exposure period being set based on the first exposure period and at least one of: a first time associated with a read out operation of the memory to a second apparatus, or a second time associated with a quantization operation by the quantizer; perform, using the quantizer, the first quantization operation of the first charge to generate a first digital output; store the first digital output in the memory; perform, using the quantizer, a second quantization operation of the second charge to generate a second digital output; and store the second digital output in the memory.

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Redmond, WA, United States of America

Tsung-Hsun Tsai