关键词: 神经信号, 模拟电路, 模拟前端, 植入式器件, 高电源抑制比, 高共模抑制比

Abstract: As the in vivo electroneurographic signals are weak with high noise and strong environment interference ， an implantable low-noise analog front-end with high power supply rejection ratio （ PSRR ） and com-mon mode rejection ratio （ CMRR ） for neural signal acquisition is proposed. Fully differential structure is used to design the preamplifier ， switch capacitor filter and variable gain amplifier of the analog front-end. Chopper stabilization technology is used to reduce the low-frequency noise and a ripple reduction loop with current DAC is used to reduce the output ripple. In this way ， the proposed analog front-end can achieve high PSRR and CMRR without increasing the original low noise. Moreover ， a front-end chip is designed via 0.18μm CMOS technology and is used for simulation. The results of layout show that （ 1 ） input-referred noise of the analog front-end is 2.6μV at the interval of 0.1Hz~10kHz ；（ 2 ） the gain of the analog front-end can switch among 46.35 ， 52.18 ， 60.02 and 66.95dB ； and （ 3 ） the CMRR and PSRR of the analog front-end are respectively 146 and 108 dB. Thus ， it draws the conclusion that the proposed analog front-end is suitable for neural signal acquisition.

Key words: neural signal, analog circuit, analog front-end, implantable devices, high PSRR, high CMRR