A 120dB 300mW stereo audio A/D converter with 110dB THD+N

Abstract

A fifth order, single-loop, multibit delta-sigma stereo audio ADC achieves 120 dB dynamic range and 110 dB THD+N while dissipating less than 300 mW of power. A feed forward path substantially reduces the signal component in the loop, enabling high dynamic range at low power levels. A second order mismatch shaper removes any nonlinearity or tones caused by element mismatch in the feedback DAC. A rough/fine input sampling scheme alleviates the loading on the input driver, improving distortion. An offset compensated switched-capacitor scheme is used in the rough buffer to avoid offset integration in AC coupled applications. Demodulation of quantization noise and delta-sigma tones is avoided by a segmented chopping technique.