Ultra low voltage switched opamp /spl Sigma//spl Delta/ modulator for portable applications

A /spl Sigma//spl Delta/ modulator for portable applications is presented operating within a large window of supply voltages. A third order fully differential non-cascaded modulator structure is designed in switched-opamp (SO) technique with common mode level shift. The circuit is realized in 0.18 /spl mu/m n-well CMOS technology and occupies an area of 0.17 mm/sup 2/. Measurements are performed for supply voltages between 0.61 V and 1.5 V. Signal-to-noise ratios (SNR) of 72 dB and 64.5 dB and signal-to-noise-and-distortion ratios (SNDR) of 70 dB and 64 dB are obtained at 16 kHz signal bandwidth at supply voltages of 0.9 V and 0.75 V, respectively.