Yield-oriented biopotential amplifier design for PCB-based active dry electrodes

In physiological measurement systems, the most critical stages are the transduction and the amplification, mainly when tolerances of components are taken into account. In this case, if there is a small difference between DC input voltages of the biopotential amplifier, its DC output voltage may be saturated, even when DC suppression circuits are used. In this paper, we propose an active biopotential electrode and, based on a yield-oriented analysis, a maximum gain condition that guarantees a constant DC output voltage of the proposed biopotential amplifier without using laser trimming. A DC Monte-Carlo simulation is performed to demonstrate our results and an experimental procedure is also carried out to analyze the proposed system by measuring heartbeat frequency.