A Low-Power Current-Reuse Analog Front-End for High-Density Neural Recording Implants

Abstract

Studying brain activity in vivo requires collecting bioelectrical signals from several microelectrodes simultaneously in order to capture neuron interactions. In this work, we present a new current-reuse analog front-end (AFE), which is scalable to very large numbers of recording channels, thanks to its small implementation silicon area and its low-power consumption. This current-reuse AFE, which is including a low-noise amplifier (LNA) and a programmable gain amplifier (PGA), employs a new fully differential current-mirror topology using fewer transistors, and improving several design parameters, such as power consumption and noise, over previous current-reuse amplifier circuit implementations. We show that the proposed current-reuse amplifier can provide a theoretical noise efficiency factor (NEF) as low as 1.01, which is the lowest reported theoretical NEF provided by an LNA topology. A foue-channel current-reuse AFE implemented in a CMOS 0.18-μm technology is presented as a proof-of-concept. T-network capacitive circuits are used to decrease the size of input capacitors and to increase the gain accuracy in the AFE. The measured performance of the whole AFE is presented. The total power consumption per channel, including the LNA and the PGA stage, is 9 μW (4.5 μW for LNA and 4.5 μW for PGA), for an input referred noise of 3.2 μV, achieving a measured NEF of 1.94. The entire AFE presents three selectable gains of 35.04, 43.1, and 49.5 dB, and occupies a die area of 0.072 mm per channel. The implemented circuit has a measured inter-channel rejection ratio of 54 dB. In vivo recording results obtained with the proposed AFE are reported. It successfully allows collecting low-amplitude extracellular action potential signals from a tungsten wire microelectrode implanted in the hippocampus of a laboratory mouse.

Noise‐power‐area optimised design procedure for OTAs with complementary input transistors for neural amplifiers

“…Table 1 Comparison of the state-of-the-art neural amplifiers TBCAS, 2012 [16] Electro. Letters, 2012 [8] BioCAS, 2013 [14] TBCAS, 2013 [5] JSSC, 2013 [17] JSSC, 2017 [13] TBCAS, 2018 [18] TBCAS, 2018 [19] This work…”

A Robust 4-channel Micro-power Low-noise Neural Recording Amplifier for Hippocampal Cognitive Prosthesis

“…Different researchers have focused on different features in their design. For example, some studies have focused on the low power of the amplifier [11,12], some have pursued low noise [13,14,15], while others have paid more attention to the NEF [16,17,18,19], high input impedance [20,21], little distortion [22,23,24] and small area [25,26]. A tradeoff exists between power, noise and area and balancing these performances in design is important.…”

Wireless and battery-free technologies for neuroengineering

“…Power supplied with such schemes must meet system-dependent power-consumption requirements. For example, electrophysiological recordings based on optimized application-specific integrated circuits (ASICs) can consume as low as a few microwatts per channel 34,[127][128][129][130] , whereas photometric recordings typically require average powers in the range of milliwatts 131 . Even with a given operation modality, power consumption may differ depending on implant location 100,119,122,132 (Table 2).…”