METHOD AND APPARATUS FOR DITHERING IN MULTI-BIT SIGMA-DELTA ANALOG-TO- DIGITAL CONVERTERS

摘要

A multi-bit (M-bit, M>1) or multi-level (nlev levels, nlev>2, encoded on M bits where M=Floor(log 2(nlev))) sigma-delta analog-to-digital converter (ADC) with a variable resolution multi-bit quantizer having its resolution (number of distinct output levels) and associated quantization thresholds changed for each voltage sample with a random or pseudo-random sequence N(n) to provide automatic dynamic dithering for removing undesired idle tones in the digital output of the sigma-delta ADC. The random integer numbers N(n) between 2 and nlev may be provided by a random or pseudo-random sequence generator, e.g., Galois linear feedback shift register in combination with digital comparators and an adder.