High Dynamic Range Audio Multi-bit 2nd Order DT DSM Hybrid SAR ADC with One Sharing DAC.

An low area cost and high resolution delta-sigma modulator for audio applications is proposed in this paper. It is a second-order switched-capacitor modulator that employs a 6-bit successive approximation register (SAR) quantizer for obtaining a high dynamic range. In addition, a R2R ladder digital-to-analog converter (DAC) is used as a sharing DAC for the SAR quantizer and the modulator to relieve the area costs. A prototype was designed and simulated by UMC 180-nm 1P6M CMOS process. It can achieve dynamic range of 105dB, SNDR of 93.7dB, and SNR of 103.8dB with bandwidth of 25kHz and power dissipation of 1.25mW. It is able to reach the state-of-the-art energy efficiency, as demonstrated by a Schreier FoM of 178 dB.