Patent ID: 6404364
Filing Date: 2002-06-11
Classification: H03M

Abstract:
A multiple stage converter for converting a sampled analog signal to a corresponding digital representation, comprising:a plurality of stages, each stage receiving an analog input signal and producing a partial digital output, a first stage receiving the sampled analog signal as the analog input signal, each stage except a last stage providing a residue output which is the analog input signal to a subsequent stage, the residue being the analog input signal to the stage less the partial digital output from the stage, possibly with a gain change, at least one stage comprising: a lower comparator defining a lower threshold within a voltage range over which the analog input signal may vary, the lower comparator receiving the analog input signal and providing a lower comparator output; an upper comparator defining an upper comparator threshold within the voltage range over which the analog input signal may vary, the upper comparator receiving the analog input signal and providing an upper comparator output; a middle comparator defining a midrange comparator threshold within the voltage range over which the analog input signal will vary, the middle comparator receiving the analog input signal and providing a middle comparator output; a dither generator for providing a dither signal; and a dither circuit for receiving the lower comparator output, the upper comparator output, the middle comparator output, and the dither signal, the dither circuit providing the partial digital output that does not include the dither signal when the analog input is in a range where the addition of dither would create uncorrectable errors.