A 20-Bit Sigma-Delta D/A for Audio Applications in 0.13um CMOS

A stereo 20-bit sigma-delta D/A primarily intend for audio applications is described in this paper. Mixed-radix number representation algorithms and high efficiency hardware realization method are used to dramatically reduce the area of the interpolation filter. Semi-digital current-mode filter is used as the reconstruction filter to achieve high dynamic range under the low power conditions. The proposed design is simulated in 0.13mum CMOS, and the overall D/A achieves 100dB SNDR in the range from 20Hz to 48KHz at an oversampling ratio of 128. The interpolator and the digital delta-sigma modulator work at a 1.2-V power supply and occupy a die area of 1.0 times 1.0mm². The analog semi-digital filter works at a 2.5-V power supply and occupies a die area of 1.4 times 1.0mm².