Direct Interference Canceling for Two-Electrode Biopotential Amplifier

Author

Hwang, In-Duk ; Webster, John G.

Author_Institution

Dept. of Electron. Eng., Daejeon Univ., Daejeon

Volume

55

Issue

11

fYear

2008

Firstpage

2620

Lastpage

2627

Abstract

A two-electrode biopotential amplifier, though simpler than a three-electrode amplifier, has problems rejecting 60 Hz power-line interference due to the imbalance of electrode-skin impedance. A direct interference canceling (DIC) scheme to reject 60 Hz interference for a two-electrode biopotential amplifier is proposed. The DIC scheme cancels differential-mode interference directly by adding to the interference to be canceled a feedback signal that has the same magnitude and frequency as the interference, but that has phase shifted 180deg. When the DIC is started by closing a switch, transient interference appears, which decreases within several seconds. In steady state, the DIC amplifier rejects a very narrow bandwidth (BW) centered at the interference frequency. The proposed circuit was implemented and the DIC operation yielded 54 dB interference canceling with 0.6 Hz rejection BW.

Keywords

amplifiers; bioelectric potentials; biomedical electronics; feedback; phase locked loops; PLL; direct interference canceling; electrode-skin impedance; feedback signal; narrow bandwidth; power-line interference; two-electrode biopotential amplifier; Biomedical engineering; Circuits; Differential amplifiers; Electrocardiography; Electrodes; Feedback; Frequency; Impedance; Interference cancellation; Operational amplifiers; Power amplifiers; Voltage; Biopotential amplifier; ECG amplifier; interference reduction; two-electrode amplifier; Algorithms; Amplifiers, Electronic; Electrodes; Electrodiagnosis; Electronics, Medical; Feedback; Humans;

fLanguage

English

Journal_Title

Biomedical Engineering, IEEE Transactions on

Publisher

ieee

ISSN

0018-9294

Type

jour

DOI

10.1109/TBME.2008.923108

Filename

4487052