A 2.7-$\mu$ W Neuromodulation AFE With 200 mVpp Differential-Mode Stimulus Artifact Canceler Including On-Chip LMS Adaptation

Abstract

We present a 65-nm CMOS neuromodulation SoC with a stimulus artifact canceler allowing simultaneous recording and stimulation. A first-order ${\Delta \Sigma }$ -modulated switched capacitor DAC injects artifact canceling charges at the LNA input, handling up to 200 mV $_{\text{pp}}$ differential-mode artifacts with only a 10% noise penalty. An on-chip LMS engine adapts tap coefficients of an integrated FIR filter that reconstructs the artifact signals. Residual artifacts are further canceled with another FIR/LMS filter in the digital backend. This canceler achieves a state-of-the-art effective dynamic range of 77 dB while retaining low power consumption. The AFE including the canceler consumes $2.7~ {\mu }\text{W}$ of power and occupies 0.18 mm2 of area per channel.