CMOS image sensor with pixel level A/D conversion
First Claim
1. An image sensor circuit comprising:
- a two dimensional array of photodetectors located within an image sensor core on an integrated circuit chip, each of said photodetectors having electrical characteristics which vary in response to light impinging upon said photodetectors; and
a plurality of analog-to-digital (A/D) converters located within said two dimensional array of photodetectors within said image sensor core, each of said A/D converters being located in a separate pixel area containing one or more of said photodetectors, each of said converters being connected to said one or more of said photodetectors in said pixel area for converting an analog output of said one or more photodetectors to binary signals, an output of each pixel area in said image sensor core comprising said binary signals.
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Abstract
An image sensor formed using a CMOS process is described herein which includes a pixel array core of phototransistors whose conductivities are related to the magnitude of light impinging upon the phototransistors. The analog signals generated by the phototransistors are converted to a serial bit stream by an A/D converter connected at the output of each phototransistor and formed in the immediate area of each phototransistor within the array core. Thus, a separate digital stream for each pixel element is output from the array core, and parasitic effects and distortion are minimized. In one embodiment, a filter circuit is connected to an output of the array core for converting the individual digital streams from each pixel element to multi-bit values corresponding to the intensity of light impinging on the phototransistor.
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Citations
18 Claims
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1. An image sensor circuit comprising:
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a two dimensional array of photodetectors located within an image sensor core on an integrated circuit chip, each of said photodetectors having electrical characteristics which vary in response to light impinging upon said photodetectors; and a plurality of analog-to-digital (A/D) converters located within said two dimensional array of photodetectors within said image sensor core, each of said A/D converters being located in a separate pixel area containing one or more of said photodetectors, each of said converters being connected to said one or more of said photodetectors in said pixel area for converting an analog output of said one or more photodetectors to binary signals, an output of each pixel area in said image sensor core comprising said binary signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for generating electrical signals representing an optical image, said method comprising the steps of:
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generating an analog signal at each pixel location in a two dimensional array of photodetectors within an image sensor core, said analog signal corresponding to a light intensity impinging on said each pixel location; converting said analog signal to digital signals at said each pixel location within said two dimensional array of photodetectors such that said each pixel location within said two dimensional array of photodetectors provides digital output signals representing a level of said analog signal; and processing said digital signals generated within said each pixel location to derive a single digital value associated with said each pixel location corresponding to said analog signal at said each pixel location over a period of time. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification