Voltage controlled oscillator with automatic center frequency calibration

A voltage controlled oscillator including an oscillator circuit with a control input, an output terminal and a variable capacitor, said oscillator circuit being adapted to provide, at said output terminal, an output signal having a frequency that is a function of the value of said variable capacitor, said value being controlled by a control voltage applied to said control input,

• characterized in that said voltage control oscillator further includes calibration means and switchable capacitor means which comprises switches and capacitors,
• said calibration means comprising comparator means coupled to a detection circuit,
• in that said comparator means has a first input to which said control voltage is applied, at least a second input to which a predetermined reference voltage is applied, and an output connected to a level input of said detection circuit,
• in that said detection circuit has a control output coupled to switch control inputs of the switches of said switchable capacitor means, said switches being adapted to connect/disconnect, in parallel to said variable capacitor, a capacitor of said switchable capacitor means,
• in that said detection circuit is adapted to activate a control signal when a signal received at said level input indicates that said control voltage has reached said predetermined reference voltage,
• and in that said detection circuit is further adapted to provide said activated control signal at said control output in order to control the switches of said switchable capacitor means, and said detection circuit includes a reset output configured to reset said control voltage.