An apparatus for demodulating an input signal that includes a frequency detector for tracking a frequency of the input signal, an oscillator and a mixer is disclosed. The input signal and an output signal of the oscillator can constitute the incoming signals for the mixer and the output signal of the mixer can constitute the demodulated input signal, wherein an arithmetic unit is arranged downstream of the frequency detector and upstream of the oscillator, wherein the tracked frequency of the input signal and a predefined second frequency constitute the incoming signals of the arithmetic unit and the arithmetic unit is designed such that it computes a control signal for the oscillator from the tracked frequency of the input signal and the predefined second frequency with the output signal of the oscillator depending on the control signal.