An oscillator system comprising: a voltage controlled oscillator circuit (111, 211, 311, 511, 611) including an input to receive an input voltage and an output to provide an oscillation signal, the input voltage controls a frequency of the oscillation signal; a frequency to voltage circuit (107, 303), the frequency to voltage circuit (107, 303) including an input to receive the oscillation signal, the frequency to voltage circuit (107, 303) including an output for producing a voltage dependent on a frequency of the oscillation signal; a comparison circuit (109, 307, 607) including an amplifier (127, 335, 635), the amplifier (127, 335, 635) includes an inverting input, a non inverting input, and an output, during a sampling phase of the comparison circuit (109, 307, 607), the non inverting input receives a reference voltage and the inverting input is coupled at least via a first switch (131, 339, 639) to the output of the amplifier (127, 335, 635) and is coupled to a first capacitor (129, 337, 637), wherein a voltage of the output of the amplifier (127, 335, 635) is sampled by the first capacitor (129, 337, 637), wherein during a comparison phase of the comparison circuit (109, 307, 607), the first switch is open and the non inverting amplifier (127, 335, 635) receives the voltage generated by the output of the frequency to voltage circuit (107, 303) and the inverting input is coupled to the first capacitor (129, 337, 637), wherein the voltage of the output of the amplifier (127, 335, 635) is provided to the input of the voltage controlled oscillator circuit (111, 211, 311, 511, 611) during the comparison phase. a voltage controlled oscillator circuit (111, 211, 311, 511, 611) including an input to receive an input voltage and an output to provide an oscillation signal, the input voltage controls a frequency of the oscillation signal; a frequency to voltage circuit (107, 303), the frequency to voltage circuit (107, 303) including an input to receive the oscillation signal, the frequency to voltage circuit (107, 303) including an output for producing a voltage dependent on a frequency of the oscillation signal; a comparison circuit (109, 307, 607) including an amplifier (127, 335, 635), the amplifier (127, 335, 635) includes an inverting input, a non inverting input, and an output, during a sampling phase of the comparison circuit (109, 307, 607), the non inverting input receives a reference voltage and the inverting input is coupled at least via a first switch (131, 339, 639) to the output of the amplifier (127, 335, 635) and is coupled to a first capacitor (129, 337, 637), wherein a voltage of the output of the amplifier (127, 335, 635) is sampled by the first capacitor (129, 337, 637), wherein during a comparison phase of the comparison circuit (109, 307, 607), the first switch is open and the non inverting amplifier (127, 335, 635) receives the voltage generated by the output of the frequency to voltage circuit (107, 303) and the inverting input is coupled to the first capacitor (129, 337, 637), wherein the voltage of the output of the amplifier (127, 335, 635) is provided to the input of the voltage controlled oscillator circuit (111, 211, 311, 511, 611) during the comparison phase.