View article

Motion and stimulation artifacts encountered in wearable sensors present difficult dynamic range (DR) and linearity challenges: AFEs need to be able to resolve μV-level signals in the presence of artifacts up to 100s of mV in amplitude while maintaining linearity without saturation, such that the signal of interest can be readily recovered during post-processing. Since it is not possible to build an amplifier with appreciable gain and linearity for >100mV inputs under <; 1V SoC-compatible supply, most high-DR AFEs instead incorporate an LNA into a ΔΣ-based ADC-direct architecture [1-3]. However, as many emerging wearable devices desire single-chip integration in scaled CMOS for size and digital performance considerations, conventional ΔΣMs, which rely on voltage-domain building blocks, suffer from reduced intrinsic gain and headroom. Instead, time-domain quantization through VCO-based AFEs benefits from …