A Highly-Digital PWM-Based Impedance Monitoring IC with 143.2dB DR and 17.7fFrms Resolution

This paper presents a highly-digital PWM-based impedance monitoring IC. It achieves a dynamic range of 143.2dB and a resolution of 17.7fF
rms
for capacitance measurements in a conversion time of 16ms, while consuming only $310.9\mu \mathrm{W}$. This corresponds to the state-of-the-art FoM of 199.2dB, a 7.5dB improvement over the prior art. This performance is achieved by a mismatch-free adjustable current stimulator, an improved PWM generator, and $2^{\mathrm{n}\mathrm{d}}$-order DCO-based ADCs.