Design of an Optimized 120-dB Dynamic Range Current-Steering DAC for Class-D Audio Amplifier

This paper presents an optimized current-steering digital to analog converter (DAC) designed for a Class-D audio amplifier. The DAC exploits the potential of a mixed-signal architecture, thus allowing to take advantage of the flexibility of the digital domain and the performance of analog solutions. The proposed converter exploits an optimized differential data weighted averaging (DDWA) and an adaptive circuit that mitigate the mismatch and the switching spikes contribution, respectively. Moreover, the switches behave as a cascode for the current generators, thus reducing cost and area and making easier the design. The presented converter achieves up to 0.0003% total harmonic distortion (THD), 120-dBA dynamic range (DR) with 1.2-V power supply and a clock frequency of 4.6-MHz, and $5.19 \mu \mathrm{V}$ of noise. The circuit has been designed in 90-nm CMOS process technology with a total estimated area of 0.072-mm ² .