Testing and calibration of a circuit arrangement

Circuit arrangement, comprising:

• a sensor electrode,
• a first circuit unit that is electrically coupled to the sensor electrode, and
• a second circuit unit that comprises a first capacitor;
• wherein the first circuit unit is configured so as to keep the electrical potential of the sensor electrode in a specifiable first reference range around a specifiable target electrical potential by the first capacitor and the sensor electrode being coupled such that matching of the electrical potential is possible;
• wherein the second circuit unit is configured such that, if the electrical potential of the first capacitor is outside a second reference range, the second circuit unit detects this event and brings the first capacitor to a first electrical reference potential, and
• wherein a connectible reference current source is provided at the sensor electrode, the reference current source providing a known reference current when the reference current source is connected to the sensor electrode, such that the reference current is injected into at least one of the sensor electrode and said circuit unit, and
• wherein the circuit arrangement has at least one of the following features:
• the circuit arrangement being configured and the reference current source being adjustable such that reference current source injects into the sensor electrode no reference current as well as a first reference current having a first current strength and at least one second reference current having a second current strength that is different from the first current strength;
• the circuit arrangement being configured to determine electrical energy transmitted from the sensor electrode to the first circuit unit, both when the reference current source is deactivated and when said source is connected, as measurement results, such that at least one of a short circuit of the sensor electrode and a connection problem between the sensor electrode and the first circuit unit can be determined from the measurement results;
• and
• the reference current source being selectively connectable to a first portion and to another, second portion of the sensor electrode, such that the reference current is injected into the first portion or into the second portion, wherein the first portion forms part of an interdigital structure and the second portion is provided in the region of a connection line or wiring between the interdigital structure and the first circuit unit.

A method for at least one of testing and calibrating a circuit arrangement, comprising a sensor electrode, a first circuit unit that is electrically coupled to the sensor electrode, and a second circuit unit that comprises a first capacitor, the first circuit unit being configured so as to keep the electrical potential of the sensor electrode in a specifiable first reference range around a specifiable target electrical potential by means of the first capacitor and the sensor electrode being coupled such that matching of the electrical potential is made possible, the second circuit unit being configured such that, if the electrical potential of the first capacitor is outside a second reference range, the unit detects this event and brings the first capacitor to a first electrical reference potential, and a connectible reference current source being provided at the sensor electrode, the reference current source providing a known reference current when the reference current source is connected to the sensor electrode,

• wherein the method comprises generating and analyzing a measurement result in a manner dependent on a reference current injected into at least one of the sensor electrode and a sensor electrode of another circuit arrangement in order to determine at least one of a short circuit of the sensor electrode and a connection problem between the sensor electrode and the first circuit unit, at least one of a short circuit of the sensor electrode and a connection problem between the sensor electrode and the first circuit unit being determined from the measurement results.