CMOS fully-differential bandpass /spl Sigma//spl Delta/ modulator using switched-current circuits

摘要

The authors present a fourth-order bandpass /spl Sigma//spl Delta/ switched-current modulator IC in 0.8 /spl mu/m CMOS single-poly technology. It is the first reported integrated circuit realisation of a bandpass /spl Sigma//spl Delta/ modulator using switched-current circuits. Its architecture is obtained by applying a lowpass to bandpass transformation (z/sup 1//spl rarr/-z/sup 2/) to a second-order lowpass modulator. It has been realised using fully-differential circuitry with common-mode feedback. Measurements show 8 bit dynamic range up to 5 MHz clock frequency.