Patent ID: 6529237
Filing Date: 2003-03-04
Classification: H04N

Abstract:
A preconditioning circuit for preconditioning an analog CCD output signal representing the output of a plurality of pixels, each pixel having associated therewith a DC reference level and a video level, comprising:a differential amplifier having positive and negative differential inputs and positive and negative differential outputs; a sampling network for sampling the CCD output signal onto the input of said amplifier to provide a sampled analog output signal from said amplifier; and an offset network for generating a predetermined analog offset signal level and offsetting the sampled input signal to the input of said amplifier by the predetermined analog offset signal level such that any error due to dark current errors in the CCD output signal and any offset errors in said amplifier are compensated for by said predetermined analog offset signal level; wherein said sampling network comprises first and second input sampling capacitors connectable on one side thereof to opposite ones of the positive and negative differential inputs of said amplifier, with the other end of each of said first and second sampling capacitors switchably connectable to the CCD output signal at different times, with the other side of said first sampling capacitor connected to the CCD output signal within a given pixel during the time said DC reference level is present to sample said DC reference level onto said first sampling capacitor, and the other side of said second sampling capacitor selectively connected to the CCD output signal during the time the video level of said given pixel is present to sample the video level onto said second sampling capacitor, and further comprising an equalization circuit for connecting the other sides of said first and second sampling capacitors together after sampling such that the absolute_video level for a given pixel is determinable as the difference between the associated video level and DC reference levels for said given pixel.