A 3rd order low power SI /spl Sigma//spl Delta/-A/D converter for voice-band applications

This paper presents a 3rd order switched current-/spl Sigma//spl Delta/-modulator. The /spl Sigma//spl Delta/-modulator operates at a sampling rate of f/sub s/=600 kHz and the signal band is f/sub b/=5.5 kHz, i.e., an oversampling factor of R=54.5 is used. Multiple input signals are used to reduce the internal signal swings which results in reduced power consumption. The shaping of the noise from the 2nd and 3rd integrator is used to allow the noise power from these integrators to be increased to further save power. The total power consumption is approximately 2.5 mW with a supply voltage of V/sub DD/=3.3 V. The maximum SNR is approximately 74.5 dB.