Active electrode circuits for capacitively coupled measurements

The topic of the article is analysis of circuits for active electrodes used at capacitively coupled measurements. The work compares differences between wet and insulate electrode. There is analyzed circuit for active electrode which uses integrated voltage follower and there are also presented and simulated improvements for proper using this kind of active electrode for capacitively coupled electrode. Each of these simulations was performed in TINA SPICE - based analog simulation program by Texas Instruments. Finally, the article presents a solution for an operational amplifier integrated into the active electrode to prevent saturation of its inputs. This solution ensures to ground operational amplifier input in the case of overrunning threshold value.