On the Reduction of Interference Due to Common Mode Voltage in Two-Electrode Biopotential Amplifiers

The circuit parameters contributing to common mode voltage interferences in two-electrode amplifiers, both isolated and nonisolated, are reviewed. For the isolated case, a more complete model than that reported in the literature is described, and a new methodology to analyze the problem is introduced. Next, the usual values of the parameters concerned are considered; and by applying the results obtained with the model and method described, some conclusions about the design of this kind of amplifier are drawn.