Low-noise high input impedance 8-channels chopper-stabilized EEG acquisition system

This paper presents the design and implementation of an 8-channel low-noise chopper-stabilized analog front-end (AFE) for electroencephalogram (EEG) acquisition system. Each channel of the AFE is composed of an AC-coupled chopper instrumentation amplifier (ACCIA), a programmable gain amplifier (PGA), and a buffer. A positive feedback loop is adopted to boost its input impedance while the low-pass property suppresses the chopping ripple. The proposed AFE is implemented in 0.35 gm CMOS technology with the ADC, MUX, digital part and other control blocks. Post-layout simulation results show that the AFE achieves 46/52/58/64 dB programmable gain, 108 dB CMRR, and 0.32 μVrms input-referred noise for a bandwidth of 0.5–150 Hz. Each channel consumes 7.5 μA from a 3 V supply.