AC coupled three op-amp biopotential amplifier with active DC suppression.

E M Spinelli; M A Mayosky

doi:10.1109/10.887943

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AC coupled three op-amp biopotential amplifier with active DC suppression.

E M Spinelli·M A Mayosky

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Abstract

A three op-amps instrumentation amplifier (I.A) with active dc suppression is presented. dc suppression is achieved by means of a controlled floating source at the input stage, to compensate electrode and op-amps offset voltages. This isolated floating source is built around an optical-isolated device using a general-purpose optocoupler, working as a photovoltaic generator. The proposed circuit has many interesting characteristics regarding simplicity and cost, while preserving common mode rejection ratio (CMRR) and high input impedance characteristics of the classic three op-amps I.A. As an example, a biopotential amplifier with a gain of 80 dB, a lower cutoff frequency of 0.1 Hz, and a dc input range of +/- 8 mV was built and tested. Using general-purpose op-amps, a CMRR of 105 was achieved without trimmings.

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E M Spinelli, M A Mayosky. 2000. AC coupled three op-amp biopotential amplifier with active DC suppression.. https://doi.org/10.1109/10.887943

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