VLSI implementation of a template subtraction algorithm for real-time stimulus artifact rejection

In this paper, we present very-large-scale integrated (VLSI) implementation of a template subtraction algorithm for stimulus artifact rejection (SAR) in real time with applicability to closed-loop neuroprostheses. The SAR algorithm is based upon an infinite impulse response (IIR) temporal filtering technique, which can be efficiently implemented in VLSI with reduced power consumption and silicon area. We demonstrate that initialization of the memory within the system architecture using the first recorded stimulus artifact significantly decreases system response time as compared to the case without memory initialization. Two sets of pre-recorded neural data from an Aplysia californica are used to simulate the functionality of the proposed VLSI architecture in AMS 0.35 µm complementary metal-oxide-semiconductor (CMOS) technology. Depending upon the reproducibility in the shape of stimulus artifacts in vivo, the system eliminates virtually all artifacts in real time and recovers the extracellular neural activity with µW-level power consumption from 1.5 V.