A 1.8 µW area-efficient bio-potential amplifier with 90 dB DC offset suppression

An area-efficient and low-power low-noise amplifier with adjustable parameters for bio-potential recording applications is presented. This amplifier replaces traditional analog filters using large AC coupling capacitor with the proposed DC offset suppression block based on Differential Difference Amplifier (DDA) structure, which allows the system to obtain good high pass characterization without using any area-consuming capacitors or resistors. It features configurable gain and bandwidth, which is suitable for various bio-potential applications and massive integration in biomedical devices. More than 90 dB DC offset suppression ratio is achieved in rejecting large DC offset and baseline drift that exist at the skin-electrode interface. The proposed bio-amplifier, designed in a 0.18 μm CMOS process and occupies only 0.027 mm² silicon area on chip, provides adjustable mid-band gain of 35.5/41.5/47.6/53.6 dB, tunable bandwidth from 0.01 Hz to 10 kHz. The back-annotated simulation results demonstrated the input-referred noise of 5.4 μVrms over 0.01 Hz-10 kHz and the total power dissipation consumed as low as 1.8 μW at 1.2 V power supply.