Karl Thompson

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

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.

Low Cost, Single-ended, 2M Ohm Input Impedance 98dB Stereo Audio A/D Converter With a Novel Front-end Sampling Network

A single-ended multibit delta-sigma stereo audio ADC is presented. A 3rd-order single-loop 10-level feed forward delta-sigma modulator is implemented. A feed forward stage and a rough/fine input sampling scheme combined with a novel front-end sampling network allows wide dynamic range at lower power, smaller die size and larger than 2M ohm input impedance. A second order mismatch shaper removes any nonlinearity or tones caused by element mismatch in the feedback DAC. It achieves 98dB dynamic range and 105dB THD with 0.5k ohm of source impedance while dissipating 60mW@5V. The chip occupies 2-mm2 area in 0.25mum-process and fits into a tiny 10-pin TSSOP package