Serial analog-to-digital converter using successive comparisons
Patent 5801657 Issued on September 1, 1998. Estimated Expiration Date: 
February 5, 2017. 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.
February 5, 2017. 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 ReferencesCMOS image sensor with pixel level A/D conversion n-bit analog-to-digital converter with n-1 magnitude amplifiers and n comparators Patent #: 5684419 InventorsApplicationNo. 795497 filed on 02/05/1997US Classes:341/155, Analog to digital conversion341/161Acting sequentiallyExaminersPrimary: Young, BrianAttorney, Agent or FirmInternational ClassH03M 001/38AbstractA method for simultaneously performing bit serial analog to digital conversion (ADC) for a potentially very large number of signals is described. The method is ideally suited for performing on chip ADC in area image sensors. In one embodiment, to achieve N-bit precision, the method employs a one-bit comparator per channel (or set of multiplexed channels) and an N-bit DAC. To achieve N bits of precision, 2N -1 comparisons are sequentially performed. Each comparison is performed by first setting the DAC output to the desired value and then simultaneously comparing each of the pixel values to that value. If a pixel value is greater than the DAC output value, its comparator outputs a one, otherwise it outputs a zero. By appropriately choosing the sequence of comparison values, the pixel values are sequentially generated. In another embodiment, the DAC is omitted and a continuous ramp signal is generated for comparison with the analog input. | |
