A −117.1-dB THD Audio DAC Utilizing Single Vector Quantizer for Simultaneous Mismatch and ISI Shaping

This article presents a high-linearity, robust-jitter tolerance digital-to-analog converter (DAC) for high-fidelity audio systems. To improve the linearity, we propose a compact digital shaper utilizing a single vector quantizer (VQ) to mitigate both DAC mismatch and inter-symbol interference (ISI) with low system complexity. Two dummy current-steering DAC (IDAC) units are incorporated to further enhance linearity at high input levels. In addition, noise-shaped segmentation is used in the shaper and IDAC, which reduces hardware complexity and retains high signal-to-noise ratio (SNR) and linearity. Finally, the third-order digital delta–sigma modulator (DSM) has its coefficients optimized to improve IDAC jitter tolerance. Fabricated in a 0.18- $\mu $ m CMOS technology, this audio DAC achieves a state-of-the-art total harmonic distortion (THD) of −117.1 dB at −2.1 dBFS. By adopting resistive degeneration, optimized biasing current, and RC filter in the IDAC unit, this work exhibits a THD plus noise (THD + N) of −107.4 dB and an A-weighted dynamic range (DR) of 111.2 dB. Thanks to the optimized digital DSM, even under a 620-ps rms clock jitter, this DAC attains an excellent THD + N of −100.9 dB.