A 900-mV low-power Delta Sigma A/D converter with 77-dB dynamic range

The design of a low-voltage and low-power Delta Sigma analog-to-digital (A/ D) converter is presented. A third-order single-loop Delta Sigma modulator topology is implemented with the differential modified switched op-amp tech nique. The modulator topology has been transformed as to accommodate half-d elay integrators. Dedicated low-voltage circuit building blocks, such as a class AB operational transconductance amplifier, a common-mode feedback amp lifier, and a comparator are treated, as well as low-voltage design techniq ues. The influence of very low supply voltage on power consumption is discu ssed. Measurement results of the 900-mV Delta Sigma A/D converter show a 77 -dB dynamic range in a 16-kHz bandwidth and a 62-dB peak signal-to-noise ra tio for a 40-mu W power consumption.