Abstract
A simple, cost effective circuit for a two-electrode non-differential biopotential amplifier is proposed. It uses a ‘virtual ground’ transimpedance amplifier and a parallel RC network for input common mode current equalisation, while the signal input impedance preserves its high value. With this innovative interface circuit, a simple non-inverting amplifier fully emulates high CMRR differential. The amplifier equivalent CMRR (typical range from 70–100 dB) is equal to the open loop gain of the operational amplifier used in the transimpedance interface stage. The circuit has very simple structure and utilises a small number of popular components. The amplifier is intended for use in various two-electrode applications, such as Holter-type monitors, defibrillators, ECG monitors, biotelemetry devices etc.
Similar content being viewed by others
References
Christov, I. I., andDotsinsky, I. A. (1988): ‘New approach to the digital elimination of 50 Hz interference from the electrocardiogram’,Med. Biol. Eng. Comput,26, pp. 431–434.
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
Dobrev, D. P. (2002): ‘Two-electrode biopotential amplifier’,Med. Biol. Eng. Comput.,40, pp. 546–549.
Dobrev, D. P. (2004): ‘Two-electrode low supply voltage electrocardiogram signal amplifier’,Med. Biol. Eng. Comput. 42, pp. 272–276.
Dobrev, D. P., andDaskalov, I. K. (2002): ‘Two-electrode biopotential amplifier with current-driven inputs’,Med. Biol. Eng. Comput.,40, pp. 12–127
Levkov, Ch., Mihov, G., Ivanov, R., Daskalov, I., Christov, I., andDotsinsky, I. (2005): ‘Removal of power-line interference from the ECG: a review of the subtraction procedure’,Biomed. Eng. Online,4:50, http://www.biomedical-engineering-online.-com/content/pdf/1475-925x-4-50.pdf
Neuman, M. R. (1998): ‘Biopotential amplifiers’ in Webster J. G. (Ed.): ‘Medical instrumentation: applications and design, 3rd edn' (John Wiley & Sons, New York, 1998), pp. 262–264
Thakor, N., andWebster, J. (1980): ‘Ground-free ECG recording with two electrodes’,IEEE Trans. Biomed. Eng.,27, pp. 699–704
Winter B. B., andWebster, J. G. (1983): ‘Reduction of interference due to common mode voltage in biopotential amplifiers’,IEEE Trans. Biomed. Eng.,30, pp. 58–62
AD620 Data Sheet, ©Analog Devices Inc., 2005, http://www.analog.com
HVC series Data Sheet, © OhmCraft Inc., 2005, http://www.ohmcraft.com
Avnet price list, 2005, http://www.em.avnet.com
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Dobrev, D., Neycheva, T. & Mudrov, N. Simple two-electrode biosignal amplifier. Med. Biol. Eng. Comput. 43, 725–730 (2005). https://doi.org/10.1007/BF02430949
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02430949