A 0.25 mW sigma-delta modulator for voice-band applications

A very low power and high resolution analog to digital converter has been developed for voice-band applications. It employs a third-order cascaded sigma-delta modulator and operates with supply range from 2 V to 5 V. When this modulator is used at an oversampling ratio (OSR) of 64 and clock frequency of 500 kHz, it achieves 81.5 dB dynamic range and 77 dB peak signal-to-noise plus distortion ratio (SNDR). The power required for this performance is only 0.25 mW at 2 V power-supply voltage.