Title :
Interference-rejection characteristics of biopotential amplifiers: a comparative analysis
Author :
Areny, Ramón Pallas
Author_Institution :
Dept. of Electron. Eng., Polytech. Univ. of Catalonia, Barcelona, Spain
Abstract :
The circuit parameters contributing to power line interference in ground-referenced, two- and three-electrode biopotential amplifiers, both isolated and nonisolated, are reviewed. The effects of external interference on different amplifiers are compared by using the ´effective coupling impedance´ concept. Next, an analysis of the effect of imbalanced input impedances is carried out. It is concluded that the interference in an isolated amplifier is not always lower than in a nonisolated one, and that it must be reduced by an adequate sharing between the CMRR (common mode rejection ratio) and the IMRR (isolation mode rejection ratio); that an increase in common mode input impedance always reduces interferences in three-electrode amplifiers but not in two-electrode amplifiers; and that in two-electrode amplifiers, not only is the matching of input op amps important, but also the tolerance of components in first-stage circuits.
Keywords :
amplifiers; bioelectric potentials; biomedical electronics; interference suppression; biopotential amplifiers; circuit parameters; common mode rejection ratio; effective coupling impedance; input op amps; interference-rejection characteristics; isolation mode rejection ratio; Costs; Coupling circuits; Electrodes; Electronic equipment; Frequency; Impedance matching; Interference; Operational amplifiers; Power amplifiers; Safety; Amplifiers; Biomedical Engineering; Electric Conductivity; Electrodes; Equipment Design; Models, Theoretical;
Journal_Title :
Biomedical Engineering, IEEE Transactions on
