28.7 A 0.00378mm2 Scalable Neural Recording Front-End for Fully Immersible Neural Probes Based on a Two-Step Incremental Delta-Sigma Converter with Extended Counting and Hardware Reuse

The extensive integration of electronics into tissue-penetrating probes improves the signal quality and reduces parasitic effects for high-density recording of it in vivo neural activity. In contrast to passive neural probes or devices implementing only part of the signal chain in the probe shank, fully immersible subcortical probes allow the recording of neural signals in deep-brain regions. This is achieved by directly digitizing brain activity in situ, thus avoiding a large base and allowing the probe to have a base and shank of equal width. However, this comes with a lower spatial resolution and an increased power density in the probe shank. To advance the concept of fully immersible probes, neural recording front-end architectures are required that reduce not only the area, but also the power per channel, thus avoiding tissue overheating due to increased power density. This paper presents a modular neural-recording front-end, which achieves these goals while also enhancing the noise and linearity performance compared to the state of the art.