An 8-channel readout front-end (RFE) for long-term sleep quality monitoring is presented in this paper and features high common-mode rejection ratio (CMRR) and low input referred noise. Each channel is composed of an AC coupled instrumentation amplifier (IA) with chopping spike filter (CSF), a programmable gain amplifier (PGA), and a buffer, while the bias generator and non-overlapping clock are shared by all channels. The proposed circuit, built in standard 0.35 µ m CMOS technology, consumes 101 µ A from 2.7 V, while occupying 5 mm2 of chip area. According to the simulation, the AC coupled IA''s CMRR is 118 dB and input referred noise is merely 0.55 µ Vrms. Meanwhile, the RFE is digitally programmable for different applications.
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