A compact recording array for neural interfaces

This paper presents a 44-channel front-end neural interface for recording both Extracellular Action Potentials (EAPs) and Local Field Potentials (LFPs) with 60 dB dynamic range. With a silicon footprint of only 0.015 mm² per recording channel this allows an unprecedented order of magnitude area reduction over state-of-the-art implementations in 0.18 μm CMOS. This highly compact configuration is achievable by introducing an in-channel Sigma Delta assisted Successive Approximation Register (ΣΔ-SAR) hybrid data converter integrated into the analogue front-end. A pipelined low complexity FIR filter is distributed across 44-channels to resolve a 10-bit PCM output. The proposed system achieves an input referred noise of 6.41 μV_rms with a 6 kHz bandwidth and sampled at 12.5 kS/s, with a power consumption of 2.6 μW per channel.