An 8-channel fully differential analog front-end for neural recording

An 8-channel, analog front-end chip for neural recording is presented in this paper. The chip consists of eight neural recording amplifiers with tunable bandwidth and gain, eight 4th-order Bessel switch capacitor filters, an 8-to-1 analog time-division multiplexer, a fully differential successive approximation (SAR) analog-to-digital converter (ADC), and a serial peripheral interface for communication. The neural recording amplifier presents a programmable gain from 53 dB to 68 dB, a tunable low cut-off frequency from 0.1 Hz to several hundred Hz, and 3.77 μV_rms referred noise. The SAR ADC digitizes signals at maximum sampling rate of 20 kS/s per channel and achieves an ENOB of 7.4. The chip is designed and fabricated in 0.18-μm CMOS process. We successfully performed simultaneous multi-channel recording in vitro experiment using the neural recording chip.