A new AC-coupled amplifier for portable ECG without reference electrode

This paper proposes a single power supply operated front-end AC coupling biopotential amplifier without reference electrode for portable electrocardiogram (ECG) with dual mode input for common-mode signal and common mode DC, which can effectively improve the Common Mode Rejection Ratio (CMRR) and the common mode impedance operating on a single power supply and therefore simplifying the circuit design. The proposed circuit design has a gain of 60 dB and a single supply of +5 V achieves a CMRR over 130 dB at 60 Hz without any trimming. Actually, in comparison between ECG without Driven Right Leg (DRL) circuit and ECG with DRL circuit, the former has a built in lead-1 ECG for better signal to noise ratio. This result is also valid for portable ECG measurement.