Abstract
A circuit was developed for a differential two-electrode biopotential amplifier. Current sources at the amplifier inputs were controlled by the common-mode voltage. This principle is well known in telephony for interfacing the telephone line with analogue-type phones. A low impedance of about 1 kΩ was obtained between each input and the common point of the circuit. The differential input impedance of 60 MΩ was obtained with the use of precision resistors. Considerable reduction in the common-mode voltages of more than 200 times resulted. The circuit can be useful for biosignal acquisition from subjects in areas of very high electromagnetic fields, where high common-mode voltages could saturate the input amplifier stages.
Similar content being viewed by others
References
Daskalov, I. K., Dotsinsky, I. A., andChristov, I. I. (1998): ‘Developments in ECG acquisition, preprocessing, parameter measurement, and recording’,IEEE Eng. Med. Biol.,17, pp. 50–58
Hardy, J. K. (1986): ‘Electronic communication technology’ (Prentice Hall, New York), p. 342
Huhta, J. C., andWebster, J. G. (1973): ‘60-Hz interference in electrocardiography’,IEEE Trans. Biomed. Eng.,20, pp. 91–101
Kanz, K. G., Russ, W., Deiler, S., Biberthaler, P., Jack, M., andMutschler, W. (2000): ‘Electromagnetic compatibility of automated external defibrillators’,Resuscitation,45, p. S16
Legerity inc, http://urwww.legerity.com (1999): Am7920 Data Sheet, © Legerity Inc.
Metting Van Rijn, A. C., Peper, A., andGrimbergen, C. A. (1990): ‘High quality recording of bioelectric events. Part 1: Interference reduction, theory and practice’,Med. Biol. Eng. Comput.,28, pp. 389–397
Metting Van Rijn, A. C., Peper, A., andGrimbergen, C. A. (1991): ‘The isolation mode rejection ratio in bioelectric amplifiers’,IEEE Trans. Biomed. Eng.,38, pp. 1154–1157
Pallas-areny, R. (1986): ‘On the reduction of interference due to common mode voltage in two-electrode biopotential amplifiers’,IEEE Trans. Biomed. Eng.,33, pp. 1043–1046
Pallas-areny, R. (1988): ‘Interference rejection characteristics of biopotential amplifiers: A comparative analysis,’IEEE Trans. Biomed. Eng.,35, 953–959
Thakor, N. T., andWebster, J. G. (1980): ‘Ground-free ECG recording with two electrodes’,IEEE Trans. Biomed. Eng.,27, 699–704
Winter, B., andWebster, J. G. (1983): ‘Reduction of interference due to common mode voltage in biopotential amplifiers’,IEEE Trans. Biomed. Eng.,30, 58–62
Wood, D. E., Ewins, D. J., andBalachandran, W. (1995): ‘Comparative analysis of power-line interference between two- or three-electrode biopotential amplifiers’,Med. Biol. Eng. Comput.,33, 63–68
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Dobrev, D., Daskalov, I. Two-electrode biopotential amplifier with current-driven inputs. Med. Biol. Eng. Comput. 40, 122–127 (2002). https://doi.org/10.1007/BF02347705
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02347705