A Fully Tunable Low-power Low-noise and High Swing EMG Amplifier with 8.26 PEF

In this paper, a low-noise low-power bio-potential amplifier for electromyogram (EMG) signals have designed and simulated in a commercially available 0.18 μm CMOS technology. In the first stage, a tunable band low-noise amplifier (TBLNA) is designed. In the second stage, a programmable gain amplifier (PGA) is utilized. Inside the TBLNA, by utilizing current splitting technique and current scaling technique in a current mirror operational transconductance amplifier (CM-OTA), a very good trade-off between power and noise is achieved. In addition, the second stage is designed to meet the maximum output swing. After post-layout simulation, the proposed amplifier has a variable gain between 40.2 dB to 57 dB while its high-pass and low-pass cutoff frequencies are 5-16 Hz and 1-1.75 kHz, respectively. Total input referred noise in the total bandwidth is 2.28 μVrms and the total current consumption is 1.35 μA at a 1.4 V supply voltage. Therefore, the noise efficiency factor (NEF) is 2.43. By utilizing a rail-to-rail structure and a noise efficient design, the power efficiency factor (PEF) of the proposed structure is 8.26 which is relatively lower than state-of-the-art EMG amplifiers while its output swing is 1.2 V. The minimum value of the common mode rejection ratio (CMRR) and power supply rejection ratio (PSRR) are 70 dB and 73 dB, respectively. Finally, the total area consumption without pads is 0.07 mm2.