Circuit arrangement having a sensor electrode, a first circuit unit, which is electrically coupled to the sensor electrode, and a second circuit unit, which has a first capacitor. The first circuit unit holds an electrical potential of the sensor electrode in a predetermined first reference range around a predetermined electrical desired potential by coupling the first capacitor and the sensor electrode such that there is a matching of their electrical potentials. If the second circuit unit detects the electrical potential of the first capacitor being outside a second reference range, the second circuit unit brings the first capacitor to a first electrical reference potential.