Design of a low electrode offset and high CMRR instrumentation amplifier for ECG acquisition systems

A current feedback instrumentation amplifier (CFIA) for electrocardiogram (ECG) acquisition systems is proposed in this paper. In order to reduce the electrode offset (EOS) and baseline drift, an electrode offset cancellation module is used. Right leg drive (RLD) module is added to improve the common mode rejection ratio (CMRR), suppress common mode interference. An operational transconductance amplifier-capacitor (OTA-C) low-pass filter is integrated at the output of the CFIA to filter out high-frequency noise caused by the ambient environment. The circuit is designed and simulated using a 0.18 μm CMOS process. The circuit operates at 2V and consumes a total current of 47μA. Simulation results show that the CMRR of the circuit can reach 129dB, and the canceled electrode offset voltage is ±200mV.