title: Low-noise two-wired buffer electrodes for bioelectric amplifiers.
abstract: Active buffer electrodes are known to improve the immunity of bioelectric recordings against power line interferences. A survey of published work reveals that buffer electrodes are almost exclusively designed using operational amplifiers (opamps). In this paper, we discuss the advantage of utilizing a single transistor instead. This allows for a simple electrode, which is small and requires only two wires. In addition, a single transistor adds considerably less noise when compared to an opamp with the same power consumption. We then discuss output resistance and gain as well as their respective effect on the common mode rejection ratio (CMRR). Finally, we demonstrate the use of two-wired buffer electrodes for a bioelectric amplifier.
authors.affiliation: Department of Information Technology and Electrical Engineering, Swiss Federal Institute of Technology, Gloriasstrasse 32, Zurich 8001, Switzerland. thomas.degen@ieee.org
authors.forename: Thomas
authors.initials: T
authors.lastname: Degen
authors.forename: Simon
authors.initials: S
authors.lastname: Torrent
authors.forename: Heinz
authors.initials: H
authors.lastname: Jäckel
mesh_terms: D000669:Amplifiers, Electronic; D016477:Artifacts; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008839:Microelectrodes; D014173:Transistors, Electronic