A low-power current-reuse analog front-end for multi-channel neural signal recording

Studying brain activity in-vivo requires to simultaneously record bioelectrical from several microelectrodes in order to capture neurons interactions. In this work, we present a new current-reuse analog front-end (AFE), which is scalable to very large number of recording channels, thanks to its small implementation area and its low-power consumption. This proposed AFE includes a low-noise amplifier (LNA) and a programmable gain amplifier (PGA) which employ fully differential folded cascode current-reuse structures leading to decreased power consumption and silicon area. Moreover, the proposed AFE presents improved output swing compared to previous current-reuse topologies by employing different common mode feedback circuits for LNA and PGA. A 4-channel system implemented in a CMOS 0.18-μm technology is presented as a proof-of-concept. Post-layout simulation results are reported to verify its performance. The total power consumption of one channel including a low-noise amplifier and a variable gain stage is 8.2 μW (4.1 μw for LNA and 4.1 μw for PGA), for an input referred noise of 3.28 μV. The entire AFE presents four selectable gains of 45.2 dB, 50.1 dB, 55.3 dB and 59.65 dB, and occupies a die area of 0.035 mm² per channel.