Pixim, Incorporated

Other

William R Bidermann

David Xiao Dong Yang

Justin Reyneri

Michael G Frank

Ricardo Jansson Motta

Hui Tian

Odutola Oluseye Ewedemi

Benjamin P Olding

Erlend Olson

Yi-Hen Wei

David X D Yang

An image capture method in a digital image sensor implements a continuous sampling technique with a massively parallel thermometer-code analog-to-digital conversion (ADC) technique to generate pixel data having an intrinsic to an ultra-high dynamic range. In one embodiment, the method includes, after an initial exposure period, sampling pixel intensity values at the pixel elements of an image sensor at multiple sampling intervals within a snapshot of a scene; providing an analog reference voltage corresponding to a decrementing digital count value; and comparing the pixel intensity values to the analog reference voltage at each of the multiple sampling intervals. If the pixel intensity value of a first pixel element is less than the analog reference voltage at a first exposure time, an output signal having a first value is generated and the digital count value is recorded as pixel data associated with the first pixel element.

Digital image capture having an ultra-high dynamic range

A video imaging system includes a digital image sensor for performing image capture operations and a digital image processor for performing image processing operations. The digital image sensor includes a sensor array outputting digital pixel data, an image buffer for storing the pixel data, a first processor and a first interface circuit for transferring the pixel data onto a pixel bus. The digital image processor includes a second interface circuit coupled to receive the pixel data from the pixel bus, a frame buffer coupled to store the pixel data, an image processing pipeline for processing the pixel data stored in the frame buffer into video data, and a second processor. The digital image sensor and the digital image processor transfer control information over a control interface bus and the digital image sensor performs the image capture operations independent of the image processing operations performed by the digital image processor.

Video imaging system including a digital image sensor and a digital signal processor

A system-on-chip imaging system includes an image sensor of a two-dimensional array of pixel elements providing pixel data representing an image of a scene, a data memory for storing pixel codewords whereby at least some of the pixel codewords are indicative of the pixel data, a programmable lookup table for providing LUT codewords as output data, and a processing unit for receiving LUT codewords from the lookup table and generating output image data. In operation, a first pixel codeword stored in the data memory is used to index the lookup table for causing the lookup table to provide a respective LUT codeword to the processing unit. The processing unit operates to perform one or more image processing functions in response to the LUT codeword. The lookup table can be programmed to perform a variety of image processing functions, including defective pixel correction, CDS subtraction, privacy masking and dark signal subtraction.

Digital CMOS image sensor incorporating a programmable multi-functional lookup table

An image capture method in a digital image sensor implements a continuous sampling technique with a massively parallel thermometer-code analog-to-digital conversion (ADC) technique to generate pixel data having an intrinsic to an ultra-high dynamic range. In one embodiment, the method includes, after an initial exposure period, sampling pixel intensity values at the pixel elements of an image sensor at multiple exposure times within a snapshot of a scene; providing an analog reference voltage corresponding to a decrementing digital count value; and comparing the pixel intensity values to the analog reference voltage at each of the multiple exposure times. If the pixel intensity value of a first pixel element is less than the analog reference voltage at a first exposure time, an output signal having a first value is generated and the digital count value is recorded as pixel data associated with the first pixel element.

A method for providing an identifier for a semiconductor chip after the manufacture of the semiconductor chip using a fabrication process includes selecting one or more circuit elements formed on the semiconductor chip where each of the circuit elements having an electrical parameter that has a time-invariant statistical process variation, measuring data values of the electrical parameter of the one or more circuit elements, processing the data values, and deriving the identifier for the semiconductor chip using the processed data values. The identifier identifies the semiconductor chip from other semiconductor chips manufactured using the fabrication process. The circuit elements can be selected from the group of bipolar transistors, MOS transistors, light detecting pixel elements, and memory cells. The chip identification method is particularly useful for identifying image sensor chips where the dark current values or the defective pixel locations can be used as the chip identifier.

Using a time invariant statistical process variable of a semiconductor chip as the chip identifier

An image sensor includes a sensor array including a two-dimensional array of pixel elements. The array of pixel elements includes a first group of photodetectors having a first sensitivity level and a second group of photodetectors having a second sensitivity level. The sensor array outputs digital signals as pixel data representing an image of a scene. In operation, the first group of photodetectors generates the output signals after a first exposure time and the second group of photodetectors generates the output signals after a second exposure time, where the first exposure time and the second exposure time are within a snapshot of the scene and the first exposure time is different than the second exposure time. When thus operated, the image sensor of the present invention provides improved color reproduction capability and improved signal to noise ratio, especially for the less sensitive photosensitive elements.

Digital image sensor with improved color reproduction

A circuit includes an analog-to-digital (A/D) converter for multiplexing between a number of analog input signals and converting the selected analog input signals to a digital code representation. The A/D converter includes a comparator having a first input terminal coupled to receive a first reference signal having a number of levels, a second input terminal coupled to receive a multiple number of analog input signals, and a third input terminal for receiving a multiple number of input select signals. The comparator includes a multiplexor coupling the multiple number of analog input signals to a multiple number of corresponding differential pairs. The multiplexor selects one of the multiple number of differential pairs based on the multiple number of input select signals. In one embodiment, the A/D converter is applied in a digital image sensor for performing pixel-level analog-to-digital conversion using a multi-channel bit serial ADC technique.

Electrically and optically symmetrical analog-to-digital converter for digital pixel sensors

An integrated image sensor having a conditioned top silicon oxide layer and/or one or more additional insulating layers/structures to reduce optical and/or electrical noise. The image sensor has an array of one or more pixels, each pixel having a photoelement formed on a substrate and configured to generate an electrical signal in response to incident light, and associated circuitry formed on the substrate and configured to process the electrical signal generated in the photoelement. In one embodiment, a portion of a top insulating layer in the integrated image sensor corresponding to each photoelement has a thickness different from the thickness of a portion of the top insulating layer corresponding to its associated circuitry to inhibit the flow of light between the associated circuitry and the photoelement and/or between the pixel and an adjacent pixel in the array. In another embodiment, the image sensor has one or more insulating structures formed on the substrate and configured to inhibit the flow of electricity between a photoelement and its associated circuitry and/or the pixel and an adjacent pixel in the array. The present invention can reduce optical and/or electrical noise and crosstalk to improve image quality and diminish artifacts in the image sensor's output.

Image sensors with underlying and lateral insulator structures

A multi-channel bit-serial analog-to-digital converter with reduced channel circuitry is described herein in which a one-bit comparator circuit is split between a first part located within an input channel and a second part located outside the input channel. The external part of the comparator and the one-bit latch are shared by a plurality of input channels. In the preferred embodiment, a two-dimensional sensor array of pixel elements is fabricated in a single integrated circuit. Each of the pixel elements is an input channel which comprises a photodetector and the front-end part of the one-bit comparator. The external part of the comparator and the one-bit latch are formed in the periphery of the sensor array and are shared by a group of pixel elements, such as a column of pixel elements. In one embodiment, by connecting the output of an inverter to the control signal terminal of the comparator, the comparator can also be used as a buffer for analog readout. This creates an analog read port for minimum amount of circuitry increase.

Multi-channel bit-serial analog-to-digital converter with reduced channel circuitry

Photo-sensors, such as photo-diodes, are formed using regions with cross-sections that increase the overall quantum efficiency of the resulting photo-sensor. The cross-sections have additional (e.g., interior) side-wall interfaces, and, in some embodiments, an additional, relatively shallow bottom interface. The increased total side-wall area and any additional shallow bottom area increase the total photo-junction volume located near the surface of the device. As a result, a greater fraction of photons having relatively small absorption lengths (e.g., blue light) will be absorbed within a photo-junction, thereby increasing the quantum efficiency for those photons. The present invention enables photo-sensors to be implemented with more uniform spectral response.

Photo-sensor cross-section for increased quantum efficiency

A system on a chip for an image sensor includes a sensor array, a readout circuit, a data memory and a processor. The sensor array includes a two-dimensional array of pixel elements and a plurality of analog-to-digital conversion (ADC) circuits where each ADC circuit is coupled to one or more pixel elements in the sensor array. The readout circuit is coupled for reading the pixel data from the sensor array. The data memory is coupled for the sensor array for storing the pixel data. The processor is coupled for processing the pixel data. In operation, the system on a chip deactivates at least one noise-inducing circuit while a noise-sensitive circuit is activated. In one embodiment, the noise-sensitive circuit is one or more of the ADC circuits, and the noise-inducing circuit is one of the readout circuit, the data memory and the processor.

Time multiplexing image processing functions for noise reduction

A circuit includes an analog-to-digital (A/D) converter for multiplexing between a number of analog input signals and converting the selected analog input signals to a digital code representation. The A/D converter includes a comparator having a first input terminal connected to receive the first signal having a number of levels, a second input terminal connected to receive a multiple number of analog input signals, and a third input terminal for receiving a multiple number of input select signals. The comparator includes a multiplexer coupling the multiple number of analog input signals to a multiple number of corresponding input signal paths. The multiplexer selects one of the multiple number of input signal paths based on the multiple number of input select signals. In one embodiment, the A/D converter is applied in a digital image sensor for performing pixel-level analog-to-digital conversion using a multi-channel bit serial ADC technique.

Analog-to-digital converter with multiplexed input channels

A digital image sensor includes a sensor array of digital pixels which output digital signals as pixel data. Each of the digital pixels includes a photodetector producing an analog signal indicative of the amount of light impinging on the sensor array and a charge transfer amplifier coupled to receive the analog signal and generate an amplified pixel voltage signal. The digital image sensor further includes analog-to-digital conversion (ADC) circuits located within the sensor array. Each of the ADC circuits is connected to one or more charge transfer amplifiers of the digital pixels for converting the amplified pixel voltage signal of each digital pixel to a digitized pixel voltage signal. The charge transfer amplifier operates to increase the sensitivity of the digital image sensor. The charge transfer amplifier can be implemented as a transfer gate with a floating diffusion as a measuring capacitor.

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Los Gatos, CA, United States of America

William R Bidermann