A 7-Channel Bio-Signal Analog Front End Employing Single-End Chopping Amplifier Achieving 1.48 NEF

This paper presents a high noise efficiency readout circuit for multi-channel bio-signal acquisition. The prototype is implemented in a 65 nm CMOS LP process, which achieves a power consumption of 2.06 $\mu$W/channel, a noise efficiency factor (NEF) of1.48, a common-mode rejection ratio (CMRR) of 105 dB at 50 Hz, and a crosstalk of -65dB by employing these new techniques, including 1) the use of single-ended amplifiers as the unit of low noise amplifier (LNA) for lower NEF, 2) single-end chopping techniques for single-ended amplifiers for suppressing low-frequency noise and offset, 3) digital-assisted DC servo loop (DDSL) for fast settling.