A Neuromodulation System With Real-Time Neural Signals Recovery Overlapped Temporally and Spectrally With Stimulation...

Continuous neural signal acquisition during electrical stimulation is essential for neuromodulation; nevertheless, it is often hindered by high-amplitude stimulation artifacts (SAs). This study presents a neuromodulation system with an application-specific integrated circuit (ASIC) that implements 2.9$\times$ faster adaptation than a fixed parameter method for the real-time recovery of neural signals fully overlapped with stimulation artifacts in both time and frequency domains, without any prior calibration. The on-chip SA removal module leverages an adaptive infinite impulse response (IIR)-based template-subtraction method with zero-multiplier operation and low computational complexity, enabling rapid template convergence and high accuracy under time-varying SAs while optimizing area and power efficiency. The stimulator incorporates a stimulation frequency dithering mechanism to minimize neural signal loss at the stimulation frequency and its harmonics during recovery. In vitro and in vivo experimental validation, including local field potential (LFP) and action potential (AP) recordings, demonstrated real-time SA removal, achieving 40 dB reduction of SA component and preserving neural signal integrity. The ASIC, fabricated using the TSMC 65 nm CMOS LP process, occupies a total die area of 1 mm². The SA removal module including on-chip memory occupies 0.15 mm² and consumes 1.3 µW. The presented system enables recovery of neural signals obscured by time-varying SAs in real time, without requiring prior calibration or external processing units.