CMOS imager with an A/D per pixel convertor
April 15, 2019. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesData acquisition and display device Feedback-compensated ramp-type analog to digital converter Microprocessor-based engine control systems Distance measuring method and apparatus that compares signals from plural photocells CMOS image sensor with pixel level A/D conversion Fiber optic scanning beam detector with Start-Of-Scan detection Solid-state image taking apparatus including photodiode and circuit for converting output signal of the photodiode into signal which varies with time at variation rate depending on intensity of light applied to the photodiode Focal plane processor Serial analog-to-digital converter using successive comparisons Image sensor employing non-uniform A/D conversion InventorsAssigneeApplicationNo. 292183 filed on 04/15/1999US Classes:341/169, Input signal compared with linear ramp341/155Analog to digital conversionExaminersPrimary: JeanPierre, PeguyAssistant: Jeanglaude, Jean Bruner Attorney, Agent or FirmForeign Patent References
International ClassH03M 001/56AbstractAn image sensor (10) which can be fabricated using conventional CMOS processes uses a comparator circuit (18) at each pixel (14) having a first input coupled to a photodetector (16) and a second input coupled to a ramp signal generator (30, 32). The ramp signal generator (30, 32) is comprised of a counter (32) and a D/A conversion circuit (30) with the analog output of the D/A conversion circuit (30) forming an analog ramp input to the comparator circuit (18). A counter circuit (32) can be used to drive the digital side of the D/A conversion circuit (30) and configured to count from 0 to 2n -1 to 0, N being the resolution of the photodetector (16). The output of the D/A conversion circuit (30) causes comparator circuit (18) to flip when the ramp signal is equal to the value of the output from the photodetector (16). The comparator circuit (18), in turn, drives a load signal to a register (38) which stores the counter values 32 from pixel (14) at the instant the comparator 18 flips. In this way an A/D conversion of the image data takes place.Other References
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