Title :
AC coupled three op-amp biopotential amplifier with active DC suppression
Author :
Spinelli, Enrique M. ; Mayosky, Miguel Angel
Author_Institution :
Dept. of Electron., Univ. Nacional de La Plata, Argentina
Abstract :
A three op-amps instrumentation amplifier (IA) 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 IA. 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.
Keywords :
bioelectric potentials; biomedical electronics; operational amplifiers; 0.1 Hz; 8 mV; 80 dB; AC coupled 3 op-amp biopotential amplifier; active DC suppression; common mode rejection ratio; controlled floating source; electrode voltage compensation; general-purpose optocoupler; high input impedance characteristics; input stage; op-amps offset voltage compensation; photovoltaic generator; Biomedical optical imaging; Electrodes; Instruments; Operational amplifiers; Optical amplifiers; Optical devices; Photovoltaic systems; Solar power generation; Stimulated emission; Voltage control; Action Potentials; Amplifiers; Artifacts; Bioelectric Energy Sources; Electric Impedance; Electric Wiring; Optics; Signal Processing, Computer-Assisted;
Journal_Title :
Biomedical Engineering, IEEE Transactions on
