Abstract: Methods and systems for performing analog-to-digital conversion are proposed. In one example, An analog-to-digital converter (ADC) comprising a quantizer, the quantizer having a first quantization resolution for a first quantization operation subrange and a second quantization resolution for a second quantization operation subrange. At least one of the first quantization resolution or the first quantization operation subrange is programmable. At least one of the second quantization resolution or the second quantization operation subrange is programmable. The quantizer is configured to: receive an input voltage; and based on whether the input voltage belongs to the first quantization operation subrange or to the second quantization operation subrange, quantize the input voltage at the first quantization resolution or at the second quantization resolution to generate a digital output.

Abstract: Disclosed herein are techniques for digital imaging. A digital pixel image sensor includes a digitizer in each pixel of a plurality of pixels, where the digitizer digitizes analog output signals from a photodiode of the pixel using a comparator, a global reference ramp signal, and a clock counter. In some embodiments, the comparator includes a pre-charging circuit, rather than a constant biasing circuit, to reduce the power consumption of each pixel. In some embodiments, each pixel includes a digital or analog correlated double sampling (CDS) circuit to reduce noise and provide a higher dynamic range.

Abstract: In one example, a method comprises: exposing a first photodiode to incident light to generate first charge; exposing a second photodiode to the incident light to generate second charge; converting, by a first charge sensing unit, the first charge to a first voltage; converting, by a second charge sensing unit, the second charge to a second voltage; controlling an ADC to detect, based on the first voltage, that a quantity of the first charge reaches a saturation threshold, and to measure a saturation time when the quantity of the first charge reaches the saturation threshold; stopping the exposure of the first photodiode and the second photodiode to the incident light based on detecting that the quantity of the first charge reaches the saturation threshold; and controlling the ADC to measure, based on the second voltage, a quantity of the second charge generated by the second photodiode before the exposure ends.

Abstract: A depth camera assembly (DCA) determines depth information within a local area by capturing images of the local area including a local region using a plurality of imaging sensors. The local region is represented by a first set of pixels in each captured image. For each image, the DCA identifies the first set of pixels corresponding to the surface in the local region and determines a depth measurement from the DCA to the local region by comparing the first set of pixels from images captured by different imaging sensors. To determine depth measurements for second sets of pixels neighboring the first set of pixels, the DCA selectively propagates depth information from the first set of pixels to second sets of pixels satisfying one or more criteria (e.g., satisfying a threshold saturation measurement or a threshold contrast measurement).

Abstract: In one example, an apparatus comprises: a first photodiode configured to convert a first component of light to a first charge, second photodiode configured to convert a second component of the light to a second charge; and an interface circuit configured to: perform a first quantization and a second quantization of the first charge to generate, respectively, a first result and a second result, the first quantization and the second quantization being associated with different light intensity ranges; provide one of the first result or the second result to represent an intensity of the first component of a pixel; perform the first quantization and the second quantization of the second charge to generate, respectively, a third result and a fourth result; and provide one of the third result or the fourth result to represent an intensity of the second component of the pixel.

Abstract: A dual-band pixel includes a backside passivation layer, a corresponding input terminal coupled to the backside passivation layer, a first n-type layer covering the backside passivation layer, a p-type layer covering the first n-type layer, a second n-type layer within the p-type layer, and a pinning layer covering the second n-type layer. A first or second voltage is applied to the corresponding input terminal to operate the dual-band pixel in a visible or infrared (IR) mode. A depth camera assembly (DCA) may include a sensor pixel array comprising a plurality of dual-band pixels. The DCA may take visible or IR images in a time multiplexed manner using the sensor pixel array and determine depth information based on the captured IR images.

Abstract: Examples of a pixel cell are disclosed. In one example, a pixel cell may include a first semiconductor layer including a photodiode and one or more transistor devices configured to convert charges generated by the photodiode into an analog signal. The pixel cell may also include a second semiconductor layer including one or more transistor devices configured to convert the analog signal to one or more digital signals. The first semiconductor layer and the second semiconductor layer may form a stack structure. In another example, a pixel cell may include a photodiode and a capacitor. The pixel cell may be operated, in a first mode of measurement, to measure the charges stored at the capacitor when the capacitor is electrically coupled with the photodiode, and in a second mode of measurement, to measure the charges stored at the capacitor when the capacitor is electrically isolated from the photodiode.

Abstract: Examples of an apparatus are disclosed. In some example, an apparatus includes a photodiode configured to generate a charge in response to incident light; a measurement capacitor to store at least a part of the charge to generate a voltage; and an analog-to-digital converter (ADC) circuit configured to: in a first measurement period, compare the voltage at the measurement capacitor against a static threshold voltage to generate a first output; in a second measurement period, compare the voltage against a varying threshold voltage to generate a second output, wherein the varying threshold voltage varies with time according to a pre-determined pattern; and generate a final output representing an intensity of the incident light based on either the first output or the second output.

Abstract: In one example, an apparatus comprises: a semiconductor substrate including a front side surface, a first photodiode to generate a first charge, a second photodiode to generate a second charge, a barrier layer between the first photodiode and the second photodiode and configured to control flow of the second charge from the second photodiode to the first photodiode, and a drain region to store the first charge and at least a first part of the second charge. The apparatus further comprises a gate on the front side surface over a first channel region between the first photodiode and the drain region to control the flow of the first charge and the at least the first part of the second charge to the drain region, and a second channel region to conduct at least a second part of the second charge away from the barrier layer when the second photodiode saturates.

Abstract: In one example, a method comprises: enabling a photodiode to, in response to incident light, accumulate residual charge, and to transfer overflow charge to a first charge storage device and a second charge storage device when the photodiode saturates; disconnecting the second charge storage device from the first charge storage device; enabling the photodiode to transfer the residual charge to the first charge storage device to cause the charge sensing unit to output a first voltage; quantizing the first voltage to generate a first digital value to measure the residual charge; connecting the second charge storage device with the first charge storage device to cause the charge sensing unit to output a second voltage; quantizing the second voltage to generate a second digital value to measure the overflow charge; and generating a digital representation of the incident light intensity based on the first digital value and the second digital value.

Abstract: 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.

Abstract: Methods and systems for reconstructing images from sensor data are provided. In one example, a method comprises: receiving input data generated by photodiodes each associated with a channel having a target wavelength range for photon-to-charge conversion; obtaining, for each channel, a plurality of channel coefficients, the plurality of channel coefficients being configured to, when combined with the input data to generate channel output data for the each channel, increase a main component of the channel output data contributed by a part of the incident light within the target wavelength range of the each channel with respect to a crosstalk component of the channel output data contributed by a part of the incident light out of the target wavelength range; and generating, for the each channel, the channel output data based on combining the input data with the plurality of channel coefficients to reconstruct an image for the each channel.

Abstract: In one example, an apparatus comprises: a comparator; a sampling capacitor having a first plate and a second plate. The first plate is coupled with an output of a charge sensing unit that senses charge generated by a photodiode, whereas the second plate is coupled with an input of the comparator. The apparatus further includes a controller configured to: at a first time, set a first voltage across the sampling capacitor based on an output voltage of the charge sensing unit; reset the charge sensing unit to set the first plate at a second voltage and to set the second plate at a third voltage based on the first voltage and the second voltage; compare, using the comparator, the third voltage against one or more thresholds; and generate, based on the comparison result, a quantization result of the output voltage of the charge sensing unit at the first time.

Abstract: Methods and systems for light sensing are provided. In one example, an apparatus comprises and an array of pixel cells and a controller. Each pixel cell of the array of pixel cells includes a photodiode configured to generate charges upon receiving incident light and a capacitor configured to accumulate the charges generated by the photodiode. The controller is configured to: start an exposure period to accumulate the charges at the pixel cells; and based on a determination that the quantity of charges accumulated by the at least one pixel cell exceeds a pre-determined threshold: end the exposure period to cause the capacitors of the array of pixel cells to stop accumulating the charges, generate an output pixel value for each pixel cell based on the charges accumulated at the capacitor of the each pixel cell within the exposure period; and provide the output pixel values to generate an image frame.

Abstract: Embodiments relate to a stacked photo sensor assembly where two substrates that are stacked vertically. The two substrates are connected via interconnects at a pixel level to provide a signal from a photodiode at a first substrate to circuitry on a second substrate. The circuitry on the second substrate performs operations that were conventionally performed on first substrate. By stacking the first and second substrates, the photo sensor assembly can be made more compact while increasing or at least retaining the photodiode fill factor of the photo sensor assembly.

Abstract: In one example, an apparatus comprises: a photodiode, a charge storage unit, and an analog-to-digital converter (ADC) circuit. In a first mode, the ADC circuit can compare a first voltage representing a quantity of the overflow charge stored at the charge storage unit against a first ramping voltage to generate a first decision; and obtain, based on the first decision output, a first digital value. In a second mode, the ADC circuit can compare a second voltage representing a quantity of residual charge stored in the photodiode against a second ramping voltage to generate a second decision, and obtain, based on the second decision, a second digital value. The ADC circuit can determine, based on one of the first decision output or the second decision output, whether the photodiode saturates, and output one of the first digital value or the second digital value to represent an intensity of incident light.

Abstract: Methods and systems for performing analog-to-digital conversion is provided. In one example, an analog-to-digital converter (ADC) circuit comprises a leakage compensation circuit and a quantizer. The leakage compensation circuit is configured to: receive an input signal, the input signal being susceptible to a drift due to a charge leakage; receive a reference signal; and generate a leakage-compensated signal pair to compensate for the charge leakage, wherein the leakage-compensated signal pair comprises one of: (a) a leakage-compensated version of the input signal and the reference signal, (b) the input signal and a leakage-compensated version of the reference signal, or (c) a leakage-compensated version of the input signal and a leakage-compensated version of the reference signal. The quantizer is configured to perform a leakage-compensated quantization of the input signal based on the leakage-compensated signal pair to generate a digital output representing the input signal.

Abstract: Examples of a wearable device are disclosed. In one example, the wearable device may include an optical network, a first sensor and a second sensor coupled with the optical network, and a processor. The first sensor and a second sensor are configured to generate, respectively, first sensor data and second sensor data related to different physical measurements, and to transmit the first sensor data and the second sensor data to the optical network. The processor is coupled with the optical network and configured to: receive at least one of the first sensor data or the second sensor data from the optical network; and determine output content of the wearable device based on the at least one of the first sensor data or the second sensor data.

Abstract: A photo sensor includes a plurality of pixel blocks, each including one or more anchor pixels and one or more non-anchor pixels. The anchor pixels produce first sensor signals and the non-anchor pixels produce second sensor signals. An amplifier circuit amplifies the first and second sensor signals. A variable bit-depth analog to digital converter (ADC) circuit quantizes amplified versions of the first sensor signals into first digitized sensor signals with a first bit-depth. The ADC circuit also quantizes amplified versions of the second sensor signals into second digitized sensor signals with a second bit-depth that is lower than the first bit depth. The second bit-depth may be selected based on anchor pixel statistics derived from the one or more first digitized sensor signals.

Abstract: A photo sensor array is divided up into multiple blocks that are operated with different exposure times. A prediction algorithm is used to predict the overall light brightness of each block and determine the exposure time of each block. Each block may also include memory to store the exposure time for the pixels in the block as well as analog-to-digital resolution for the block.