Figure 2

Curves of percent interface reactance versus time using integrated circuits with different offset currents as pre-amplifiers: μA741 (black squares); LF356 (open circles); AD523 (open triangles), from top to bottom. Three curves for each amplifier. There is a large difference in one set of data (for μA741) compared to the other two data sets for the same device. Such difference becomes smaller for LF356 and AD523 as the input bias offset currents further decrease in these devices. This is very likely due to the large industrial variability of these op-amps.