What is the minimum input impedance required for a differential amplifier?

The minimum input impedance required for a differential amplifier is crucial to ensure that the amplifier does not significantly load the source from which it is receiving its signal. A very high input impedance is important because it minimizes the effect on the signal being measured, which is paramount in neuromonitoring applications where maintaining the integrity of the electrical signals from biological tissues is essential.

In the context of differential amplifiers, the higher the input impedance, the less the current draw from the input sources, allowing those sources to maintain their voltage characteristics without distortion. A minimum input impedance of 100 megohms is typically required to achieve this goal, especially in sensitive applications such as neurophysiologic monitoring, where the signals can be very small and at risk for being drowned out by noise.

While other values for input impedance may be considered, they may not provide the same level of protection against loading effects or noise. Thus, a minimum input impedance of 100 megohms effectively ensures optimal performance of the differential amplifier, safeguarding the fidelity of the physiological signals being monitored.