A Novel Technique for the CMRR Improvement in a Portable ECG System

This paper presents a new technique to improve the quality of the ECG signals, increasing the Common Mode Rejection Ratio (CMRR). We developed a portable wireless Bluetooth ECG system able to acquire 12 leads, communicating with Smartphones and PCs. Many experiments have been made for measuring CMRR decay due to the difference on skin-electrodes impedances, the asymmetries of the amplifiers input stages and external components. Using some digital potentiometers, the system is able to compensate for these, increasing the CMRR of about 18 dB.