title: A 160 μW 8-Channel Active Electrode System for EEG Monitoring.
abstract: This paper presents an active electrode system for gel-free biopotential EEG signal acquisition. The system consists of front-end chopper amplifiers and a back-end common-mode feedback (CMFB) circuit. The front-end AC-coupled chopper amplifier employs input impedance boosting and digitally-assisted offset trimming. The former increases the input impedance of the active electrode to 2 GΩ at 1 Hz and the latter limits the chopping induced output ripple and residual offset to 2 mV and 20 mV, respectively. Thanks to chopper stabilization, the active electrode achieves 0.8 μVrms (0.5-100 Hz) input referred noise. The use of a back-end CMFB circuit further improves the CMRR of the active electrode readout to 82 dB at 50 Hz. Both front-end and back-end circuits are implemented in a 0.18 μm CMOS process and the total current consumption of an 8-channel readout system is 88 μA from 1.8 V supply. EEG measurements using the proposed active electrode system demonstrate its benefits compared to passive electrode systems, namely reduced sensitivity to cable motion artifacts and mains interference.
authors.lastname: Jiawei Xu
authors.forename: R F
authors.initials: RF
authors.lastname: Yazicioglu
authors.forename: B
authors.initials: B
authors.lastname: Grundlehner
authors.forename: P
authors.initials: P
authors.lastname: Harpe
authors.forename: K A A
authors.initials: KA
authors.lastname: Makinwa
authors.forename: C
authors.initials: C
authors.lastname: Van Hoof