Oscillator with switchable varactor diodes

An oscillator having a first frequency-determining elements for providing a first oscillation frequency, characterized in that said oscillator further comprises:

• second frequency-determining elements connectable to the first frequency-determining elements for adjusting the oscillator to a second oscillation frequency, said second frequency-determining elements comprise a capacitance diode;
• a device for tuning the second frequency-determining element, said device comprising a first driver stage for generating a bias voltage for the capacitance diode of the second frequency-determining elements;
• a switching diode for connecting the second frequency-determining elements to the first frequency-determining elements;
• and
• a supply circuit coupled to said switching diode for optionally switching said switching diode between a conducting state and a blocked state, said supply circuit comprises a controllable current source and a second driver stage for controlling the controllable current source, wherein the first and second driver stages each comprise a differential amplifier having a first and a second input, the differential amplifiers being controlled by a common control signal at the respective first inputs, and the respective second inputs receive respective threshold values of different levels which are dimensioned in such a way that the threshold value applied to the second driver stage limits a control range of the first driver stage fixed by the threshold value applied to the first driver stage.