Abstract: A frequency synthesizer usable in a wireless communication device is disclosed that may ensure a low phase noise and an improved performance. The frequency synthesizer has a phase locked loop comprising a controllable oscillator generating an output signal with an output frequency that can be adjusted within a predefined frequency range dependent on the value of a first control signal. A phase/frequency detector generates an error signal in response to a phase and/or frequency difference between an input signal generated by frequency dividing said output signal, and a reference signal. A loop filter generates the first control signal based on said error signal and outputs same to the controllable oscillator. A control unit generates a second control signal from the loop filter signal and provides the second control signal to the controllable oscillator, which is arranged for modifying the predefined frequency range based on the second control signal.