Embedded Electrocardiographic Amplifier without Reference Electrode

The present paper introduces a patient-friendly embedded electrographic (ECG) amplifier. In contrast to the standard ECG amplifier, the presented system uses only two electrodes to insure unobtrusiveness and compact design. The abandoned third reference electrode and required low power consumption introduce problems in ECG signal preamplification and handling. In order to meet them, a novel adaptive cancellation of 50 Hz power line interference in combination with gain/attenuation controlling is designed and implemented. In particular, the interference is reduced by the use of a self-generated 50 Hz signal with an adoptively adjusted amplitude and phase. On the other hand, the gain/attenuation of the ECG signal is controlled in a way that the range of the analog-to-digital converters is efficiently used. The introduced ECG amplifier without the reference electrode facilitates the portable minimally obtrusive monitoring with potential possibilities of on-site diagnosis