Offset digital dither generator
AssigneeTektronix, Inc.
InventorsPhilip S. Crosby, Dale A. Jordan
Life of this patent
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Abstract
A digital dither generator is described which produces a series of discrete analog values which remain constant for each repetition of a signal being digitized. These analog values are summed with the analog input value being digitized. The dither states exhibit two useful characteristics; a bit-reversal scheme in which a sequence of dither values is used to progressively maximize the resolution of the digitizer and a technique of offsetting the values by a known amount to statistically improve digitizer accuracy.
Claims7
A system for converting a repetitive analog input signal to an equivalent digital representation, the system including means for generating a dither signal, means for combining the analog signal with the dither signal, and means for quantizing the resultant combined signal to provide a digital representation thereof, characterized in that
- said dither signal generating means generates a repetitive sequence of voltage levels corresponding in magnitude to different fractional and whole multiples of a digital bit produced by said quantizing means, and
- different repetitions of said analog input signal are sequentially combined with the different dither voltage levels of said sequence.
In a system for converting a repetitive analog input signal to an equivalent digital representation, which system includes means for generating a dither signal, means for combining the analog signal with the dither signal, and means for quantizing the resultant combined signal, an improved dither signal generator comprising
- means for generating clock pulses at a rate equal to the repetition rate of said analog input signal,
- counter means for counting said clock pulses and providing an n-bit digital output signal indicating the number of counted pulses, and
- digital-to-analog signal converter means for converting said digital output signal to an analog voltage level,
- said converter means producing, in response to successive digital output signals from said counter, a sequence of voltage levels corresponding to different integer and fractional values of a digital bit produced by said quantizing means.
Dependencies are inferred from the claim text.