A 101 dB DR 1.1 mW audio delta-sigma modulator with direct-charge-transfer adder and noise shaping enhancement

A low-power audio delta-sigma modulator (DSM) is presented. Two new techniques are proposed to reduce the overall power dissipation of the modulator: a power-efficient direct-charge-transfer adder is employed, and noise-shaping enhancement is implemented by feeding the differentiated quantization noise to the input of the second integrator. The measured power dissipation is 1.1 mW, the dynamic range is 101.3 dB, the spur-free dynamic range is 112 dB and the signal-to-noise-plus-distortion ratio is 99.3 dB. The power efficiency of this design is among the best in DSMs with high (over 15) ENOBs.