A Digitally Corrected 5-mW 2-MS/s SC $\Delta\Sigma$ ADC in 0.25- $\mu$m CMOS With 94-dB SFDR

A digital correction scheme that allows a switched-capacitor (SC)
$\Delta\Sigma$
ADC to operate with significantly reduced power consumption is proposed. As power dissipation is reduced in the integrators, nonlinear settling errors cause increasing harmonic distortion. The correction technique uses a polynomial approximation to correct the nonlinearity and reduce distortion in the post-filtered digital output. With correction, experimental results yield a peak SNDR of 75 dB, a THD of
${-}90$
dB and a SFDR of 94 dB. The total analog power dissipation of the corrected modulator is 5 mW at 2.4
$~$
V, saving 38% over a similarly performing uncorrected modulator output. The active area is 0.39 mm
$^2$
in 0.25-
$\mu$
m CMOS.