A 2-Electrode ECG Amplifier with 0.5% Nominal Gain Shift and 0.13% THD in a 530mV pp Input Common-Mode Range

This paper presents a 56nV/√Hz instrumentation amplifier (IA) for the 2-electrode Electrocardiogram (ECG) signal acquisition. The IA utilizes active lead bias, direct electrode offset filtering, and negative-impedance compensation to improve the common-mode rejection ratio (CMRR), the DC electrode offset (DEO) tolerance, and the input impedance, respectively. The use of a linear input transconductance and drain voltage regulation increases the IA's resilience to signal-dependent errors, leading to a nominal voltage gain shift of less than 0.5% and a total harmonic distortion (THD) of less than 0.13% in a wide input common-mode range of 530mV pp .