A frequency signal generator includes a controllable oscillator unit, a frequency control unit and an error detection unit. The controllable oscillator unit generates and provides a frequency signal. The frequency control unit generates a frequency control signal and the controllable oscillator unit varies a frequency of the frequency signal based on the frequency control signal. Further, the error detection unit receives the frequency control signal, detects an error within the frequency control signal and provides an error signal. The error signal comprises information on a detected error.