A 0.6-V 82-dB delta-sigma audio ADC using switched-RC integrators

A 0.6-V 2-2 cascaded audio delta-sigma ADC is described. It uses a resistor-based sampling technique which achieves high linearity and low-voltage operation without subjecting the devices to large terminal voltages. A low-distortion feed-forward topology combined with nonlinear local feedback results in enhanced linearity by reducing the sensitivity to opamp distortion, and allows increased input amplitude, resulting in higher SNDR. The modulator achieves 82-dB dynamic range and 81-dB peak SNDR in the A-weighted audio signal bandwidth with an OSR of 64. The total power consumption of the modulator is 1 mW from a 0.6-V supply. The prototype occupies 2.9 mm² using a 0.35-μm CMOS technology.