Abstract: In some embodiments, an image sensor is provided. A signal processing unit of the image sensor is configured with executable instructions that cause the signal processing unit to perform actions comprising: reading a captured scene from a pixel array; reading a value from a test initiation register; in response to determining that the value indicates a test mode: processing the captured scene to detect a region of interest associated with the value; and providing the region of interest to a first interface for transmission to a host device; and in response to determining that the value does not indicate the test mode: analyzing the captured scene using a computer vision technique to selectively generate a signal based on the analysis of the captured scene; and selectively providing the signal to a second interface for transmission to the host device.

Abstract: Fixed pattern noise (FPN) reduction techniques in image sensors operated with pulse illumination are disclosed herein. In one embodiment, a method includes, during a first sub-exposure period of a frame, (a) operating a first tap of a pixel to capture a first signal corresponding to first charge at a first floating diffusion, the first charge corresponding to first light incident on a photosensor, and (b) operating a second tap of the pixel to capture a first parasitic signal corresponding to FPN at a second floating diffusion. The method further includes, during a second sub-exposure period of the frame, (a) operating the second tap to capture a second signal corresponding to second charge at the second floating diffusion, the second charge corresponding to second light incident on the photosensor, and (b) operating the first tap to capture a second parasitic signal corresponding to FPN at the first floating diffusion.

Abstract: Fixed pattern noise (FPN) reduction techniques in image sensors operated with pulse illumination are disclosed herein. In one embodiment, a method includes, during a first sub-exposure period of a frame, (a) operating a first tap of a pixel to capture a first signal corresponding to first charge at a first floating diffusion, the first charge corresponding to first light incident on a photosensor, and (b) operating a second tap of the pixel to capture a first parasitic signal corresponding to FPN at a second floating diffusion. The method further includes, during a second sub-exposure period of the frame, (a) operating the second tap to capture a second signal corresponding to second charge at the second floating diffusion, the second charge corresponding to second light incident on the photosensor, and (b) operating the first tap to capture a second parasitic signal corresponding to FPN at the first floating diffusion.

Abstract: Low power event driven pixels and reset control circuits for the same are disclosed herein. In one embodiment, an event driven pixel comprises a photosensor; a photocurrent-to-voltage converter coupled to the photosensor; and a difference circuit coupled to the photocurrent-to-voltage converter. The difference circuit includes a source follower transistor and is configured to generate a signal at a gate of the source follower transistor that is based on a voltage output from the photocurrent-to-voltage converter. The difference circuit is further configured to output a difference signal in response to assertion of a row select signal. The event driven pixel can further include a reset control circuit coupled to the difference circuit and configured to initialize the difference circuit, and to reset the difference circuit when the difference signal output from the event driven pixel indicates a change in the voltage greater than a threshold amount.

Abstract: Low power event driven pixels with passive, differential difference detection circuitry (and reset control circuits for the same) are disclosed herein. In one embodiment, an event driven pixel comprises a photosensor, a photocurrent-to-voltage converter, and a difference circuit. The difference circuit includes (a) a first circuit branch configured to sample a reference light level based on a voltage output by the photocurrent-to-voltage converter, and to output a first analog light level onto a first column line that is based on the reference light level; and (b) a second circuit branch configured to sample a light level based on the voltage, and to output a second analog light level onto a second column line that is based on the light level. A difference between the second analog light level and the first analog light level indicates whether the event driven pixel has detected an event in an external scene.

Abstract: A method for estimating a signal charge collected by a pixel of an image sensor includes determining an average bias that depends on the pixel's floating-diffusion dark current and pixel-sampling period. The method also includes determining a signal-charge estimate as the average bias subtracted from a difference between a weighted sum of a plurality of N multiple-sampling values each multiplied by a respective one of a plurality of N sample-weights.

Abstract: A time-of-flight sensor includes a pixel array of pixel circuits. A first subset of the pixel circuits is illuminated by reflected modulated light from a portion of an object. A second subset of the pixel circuits is non-illuminated by the reflected modulated light. Each pixel circuit includes a floating diffusion that stores a portion of charge photogenerated in a photodiode in response to the reflected modulated light. A transfer transistor transfers the portion of charge from the photodiode to the floating diffusion in response to modulation by a phase modulation signal. A modulation driver block generates the phase modulation signal and is coupled to a light source that emits the modulated light to the portion of the object. The modulation driver block synchronizes scanning the modulated light emitted by the light source across the object with scanning of the first subset of the pixel circuits across the pixel array.

Abstract: An optical sensor includes a pixel array of pixel cells. Each pixel cell includes photodiodes to photogenerate charge in response to incident light and a source follower to generate an image data signal in response to the charge photogenerated from the photodiodes. An image readout circuit is coupled to the pixel cells to read out the image data signal generated from the source follower of at least one of the pixel cells of a row of the pixel array. An event driven circuit is coupled to the pixel cells to read out the event data signals generated in response to the charge from the photodiodes of another row of the pixel cells of the pixel array. The image readout circuit is coupled to read out the image data signal and the event driven circuit is coupled to read out the event data signals from pixel array simultaneously.

Abstract: Low power event driven pixels with passive difference detection circuit (and reset control circuits for the same) are disclosed herein. In one embodiment, an event driven pixel comprises a photosensor; a photocurrent-to-voltage converter, and a difference circuit. The difference circuit includes a source follower transistor and a switched-capacitor filter having an input coupled to the photocurrent-to-voltage converter and an output coupled to a gate of the source follower transistor. The switched-capacitor filter includes a first capacitor coupled between the input and the output of the switched-capacitor filter, a second capacitor having a first plate coupled to the output of the switched-capacitor filter, and a reset transistor coupled between a reference voltage and the output of the switched-capacitor filter. The difference circuit is configured generate a difference signal that is indicative of whether the event driven pixel has detected an event in an external scene.

Abstract: A method for estimating a signal charge collected by a pixel of an image sensor includes determining an average bias that depends on the pixel's floating-diffusion dark current and pixel-sampling period. The method also includes determining a signal-charge estimate as the average bias subtracted from a difference between a weighted sum of a plurality of N multiple-sampling values each multiplied by a respective one of a plurality of N sample-weights.

Abstract: A time-of-flight sensor includes an integrated circuit chip in which a voltage regulator and a load are disposed. The load includes a grouping of pixel circuits and modulation driver that is supplied power from the voltage regulator. The grouping of pixel circuits included in a pixel array disposed in the integrated circuit trip. Each one of the pixel circuits includes a photodiode configured to photogenerate charge in response to reflected modulated light, a floating diffusion configured to store a portion of charge photogenerated in the photodiode, and transfer transistor to transfer the portion of charge from the photodiode to the floating diffusion in response to a phase modulation signal generated by the modulation driver. A feedback circuit is coupled between the load and the voltage regulator and is coupled to receive a feedback signal from the feedback circuit in response to the load.

Abstract: A time-of-flight pixel array includes photodiodes that generate charge in response to incident reflected modulated light. First transfer transistors transfer a first portion of the charge from the photodiodes in response to a first modulation signal and second transfer transistors transfer a second portion of the charge from the photodiodes in response to a second modulation signal, which is an inverted first modulation signal. First floating diffusions are coupled to the first transfer transistors. A binning transistor is coupled between one of the first floating diffusions and another one of the first floating diffusions. A first memory node is coupled to one of the first floating diffusions through a first sample and hold transistor and a second memory node is coupled to another one of the first floating diffusions through a second sample and hold transistor.

Abstract: A time-of-flight sensor includes a pixel array of pixel circuits. A first subset of the pixel circuits is illuminated by reflected modulated light from a portion of an object. A second subset of the pixel circuits is non-illuminated by the reflected modulated light. Each pixel circuit includes a floating diffusion that stores a portion of charge photogenerated in a photodiode in response to the reflected modulated light. A transfer transistor transfers the portion of charge from the photodiode to the floating diffusion in response to modulation by a phase modulation signal. A modulation driver block generates the phase modulation signal and is coupled to a light source that emits the modulated light to the portion of the object. The modulation driver block synchronizes scanning the modulated light emitted by the light source across the object with scanning of the first subset of the pixel circuits across the pixel array.

Abstract: A time-of-flight pixel circuit includes a photodiode configured to generate charge in response to modulated light reflected from an object. First and second transfer transistors are coupled to the photodiode. The first transfer transistor transfers a first portion of charge from the photodiode in response to a first modulation signal and the second transfer transistor transfers a second portion of charge from the photodiode in response to a second modulation signal. The second modulation signal is an inverted first modulation signal. A first floating diffusion is coupled to the first transfer transistor to receive the first portion of charge in response to a first modulation signal. Each one of a first plurality of sample and hold transistors is coupled between a respective one of a first plurality of memory nodes and the first transfer transistor.

Abstract: An event sensing system includes a pixel array including a plurality of event driven pixel circuits configured to be illuminated by incident light. The event driven pixel circuits are configured to generate an event current in response to a detection of an event in the incident light. Output signals of a row of the pixel array are configured to be read out from the row of the pixel array to a line buffer in response to the detection of the event in the incident light. A random number generator is configured to randomly generate a filtering mask. A mask circuit is the output signals of the row of the pixel array from the line buffer and the filtering mask from the random number generator to filter the output signals of the row of the pixel array in response to the filtering mask.

Abstract: A pixel circuit includes a photodiode configured to photogenerate charge in response to reflected modulated light incident upon the photodiode. A first floating diffusion is configured to store a first portion of charge photogenerated in the photodiode. A first transfer transistor is configured to transfer the first portion of charge from the photodiode to the first floating diffusion in response to a first phase signal. A first storage node is configured to store the first portion of charge from the first floating diffusion. A first decoupling circuit has a first output responsive to a first input. The first input is coupled to the first floating diffusion and the first output is coupled to first storage node. A voltage swing at the first output is greater than a voltage swing at the first input.

Abstract: An event sensing system includes a pixel array including a plurality of event driven pixel circuits configured to be illuminated by incident light. The event driven pixel circuits are configured to generate an event current in response to a detection of an event in the incident light. Output signals of a row of the pixel array are configured to be read out from the row of the pixel array to a line buffer in response to the detection of the event in the incident light. A random number generator is configured to randomly generate a filtering mask. A mask circuit is the output signals of the row of the pixel array from the line buffer and the filtering mask from the random number generator to filter the output signals of the row of the pixel array in response to the filtering mask.

Abstract: An image sensor has diffractive microlenses over pixels with central structures and ring(s) of material having index of refraction different from that of background material. Disposed beneath the diffractive microlenses are photodiodes that permit determining ratios of illumination of peripheral photodiodes to illumination of central photodiodes of the pixels, and, in embodiments, circuitry for determining said ratio. In embodiments, the ratio is used to find illumination wavelengths; and in other embodiments the ratio is used to determine focus of an imaging lens providing illumination. A method determines color by passing light through a diffractive lens disposed above photodiodes of the diffractive pixel and determining color from illumination peripheral and central photodiodes. An autofocus method of determining focus includes passing light through a diffractive lens and determining focus from illumination of peripheral photodiodes and central photodiodes of the pixel.

Abstract: An optical sensor includes a pixel array of pixel cells. Each pixel cell includes photodiodes to photogenerate charge in response to incident light and a source follower to generate an image data signal in response to the charge photogenerated from the photodiodes. An image readout circuit is coupled to the pixel cells to read out the image data signal generated from the source follower of at least one of the pixel cells of a row of the pixel array. An event driven circuit is coupled to the pixel cells to read out the event data signals generated in response to the charge from the photodiodes of another row of the pixel cells of the pixel array. The image readout circuit is coupled to read out the image data signal and the event driven circuit is coupled to read out the event data signals from pixel array simultaneously.

Abstract: A semiconductor structure includes a semiconductor layer of a first conductivity type, a photosensitive zone configured such that photogenerated charges may be accumulated in a first potential well, a region of the first conductivity type, formed in the semiconductor layer, for temporarily storing the photogenerated charges in a second potential well, a transfer gate between the region of the second conductivity type and the photosensitive zone for defining a potential barrier between the first and second potential wells during a non-transfer phase, and for eliminating the potential barrier between the first and second potential wells during a transfer phase, and a readout structure for reading out the temporarily stored photogenerated charges, which includes a JFET, the gate of which is formed by the region of the second conductivity type.