A 113-dB DSD audio ADC using a density-modulated dithering scheme

A stereo audio delta-sigma A/D converter is implemented to support both the standard pulse-code modulation audio and the direct stream digital (DSD) output format. It provides all the standard audio rates up to 192 kHz. A sixthorder, single-bit modulator is employed to achieve the noise performance as well as the bitstream output required by the DSD format. A novel density-modulated dithering scheme is utilized to dramatically reduce the tone level in the signal band without compromising the stability of the high-order modulator. This analog-to-digital converter achieves a dynamic range of 113 dB and a total harmonic distortion +N of 105 dB. It is fabricated in a 0.35-/spl mu/m CMOS process with a die size of 10.5 mm/sup 2/.