An Ultra-Low Noise, Power-Efficient AFE based on Current-Reuse and splitting techniques for Multibiosignal acquisition

Abstract

This paper presents an ultra-low-power and low-noise Bio-analog front-end (BioAFE) with a tunable frequency response for bio signals acquisition such as EEG, ECG, and EMG. The proposed BioAFE consists of only two stages. In the first stage, the proposed operational transconductance amplifier (OTA) successfully employs current reuse and gain boosting techniques to enhance power efficiency and gain. In the second stage of the proposed BioAFE, the band-pass filter (BPF) and variable gain amplifier (VGA) are integrated to optimize energy consumption and reduce chip area. A current-splitting technique is proposed in this stage, which adjusts the high cut-off frequency by modifying the OTA’s transconductance without additional power consumption. Consequently, the proposed BioAFE can provide a gain of 65 dB, 54 dB and 44 dB with bandwidth of (0.4–100 Hz), (0.5–500 Hz) and (12–1500 Hz) for EEG, ECG and EMG signals, respectively. The proposed BioAFE, which employs chopper stabilization and positive feedback loop (PFL) techniques in its first stage, has successfully improved the input-referred noise and input impedance to 309 nVrms and 9 GΩ, respectively. The proposed BioAFE operates with a 0.8 V power supply and consumes a total power of 144 nW. The proposed structure has been designed and evaluated using Cadence software on TSMC 65 nm CMOS technology, occupying a chip area of 0.0645 mm².