Subtractive dithering technique for delta-sigma modulator

This paper presents a novel subtractive dithering technique used in delta-sigma modulators which improves the spectral integrity of the modulators while minimizing the tradeoffs due to the use of dither. Dithering is commonly used in delta-sigma modulators to eliminate idle tones. The proposed technique adds dither at input of the quantizer and subtracts the dither in the analog domain at input of the modulator and in the digital domain at the output of modulator. The simulation results prove that when compared to the conventional dithering technique, this new subtractive dithering technique achieves the idle tone-free result but does not have the traditional drawbacks such as increased integrator output swing and in-band noise floor degradation.