Device for measuring a measurement variable

An apparatus for measuring a measured variable, comprising:

• a first inductance,
• at least one measurement inductance to sense the measured variable and coupled to the first inductance,
• a capacitance interconnected with the first inductance to form a parallel resonant circuit, and
• an electronic control unit,
• wherein the electronic control unit is connected directly to the parallel resonant circuit and is configured to excite the parallel resonant circuit into oscillation at an excitation frequency that is derived from a clock of the electronic control unit,
• wherein the electronic control unit has at least one analog-to-digital converter having a signal input connected directly to the at least one measurement inductance for picking up a signal,
• wherein the electronic control unit has a distortion signal generator having a distortion signal output, the distortion signal generator delivering a distortion signal at a distortion signal reference point,
• wherein the distortion signal output is coupled to the analog-to-digital converter exclusively by passive components,
• wherein the electronic control unit is configured to measure the signal at intervals, a number of measured values being picked up within each interval, and
• wherein the electronic control unit is configured to perform a frequency analysis of the measured values of a respective interval and to determine at least one characteristic value, indicating the measured variable, of the signal at an evaluation frequency.