Radio transceiver having a phase-locked loop circuit

An apparatus comprising:

• a first voltage controlled oscillator configured to operate in at least a first frequency range;
• at least a second voltage controlled oscillator configured to operate in at least a second frequency range;
• a switching arrangement having selectable positions configured to provide an input to and an output of the first voltage controlled oscillator or the at least second voltage controlled oscillator;
• a reference oscillator;
• a frequency divider operatively coupled with the output of the switching arrangement;
• a phase detector operatively coupled with an output of the frequency divider and the reference oscillator, configured to provide a phase of an output of said reference oscillator relative to the signal of the frequency divider;
• a charge pump operatively coupled with the input of the switching arrangement and the phase detector;
• and
• a circuit operatively coupled with the operative coupling between said phase detector and said charge pump, the circuit configured to provide at least one direct current output signal related to linearity of an operation state of said first or at least said second voltage controlled oscillator currently connected to said switching arrangement, said at least one direct current output signal for switching said switching arrangement from the voltage controlled oscillator currently connected to the switching arrangement to another of said voltage controlled oscillators if said at least one direct current output signal indicates that the operation of the currently connected voltage controlled oscillator is not linear.

An apparatus, comprising:

• a first voltage controlled oscillator disposed and arranged so that it is connected into a phase-locked loop circuit by a switching arrangement, configured to provide an output signal in response to an applied input voltage when switched into the phase-lock loop circuit;
• a phase detector, responsive to a signal associated with said output signal and with a reference signal, configured to provide a signal indicative of the input voltage to be applied to the voltage controlled oscillator connected into the circuit;
• and
• a circuit, responsive to the signal indicative of the input voltage to be applied to the voltage controlled oscillator connected into the circuit, configured to provide at least one direct current output signal related to linearity of an operation state of said voltage controlled oscillator and useable for indicating whether to switch to a voltage controlled oscillator other than the voltage controlled oscillator connected into the circuit if said at least one direct current output signal indicates that the operation state of said voltage controlled oscillator is not linear based on said at least one direct current output signal.

A method comprising:

• providing a detector signal associated with a phase comparison of a reference oscillator output signal and a signal associated with an output signal of a voltage controlled oscillator output connected into a circuit;
• providing at least one direct current output signal related to linearity of an operation state of the voltage controlled oscillator based on said detector signal;
• and
• switching to another voltage controlled oscillator so that said other voltage controlled oscillator is connected into said circuit if said at least one direct current output signal indicates that the operation state of said voltage controlled oscillator is not linear.

An apparatus comprising:

• means for providing a detector signal associated with a phase comparison of a reference oscillator output signal and a signal associated with an output signal of a voltage controlled oscillator output connected into a circuit;
• means for providing at least one direct current output signal related to linearity of an operation state of the voltage controlled oscillator based on said detector signal;
• and
• means for switching to another voltage controlled oscillator so that said other voltage controlled oscillator is connected into said circuit if said at least one direct current output signal indicates that the operation state of said voltage controlled oscillator is not linear.

A method comprising:

• setting a switching arrangement to connect to a first voltage controlled oscillator;
• locking a phase locked loop associated with said first voltage controlled oscillator to start operation with a frequency close to an end of a frequency range of a transceiver associated with said phase locked loop;
• increasing a lock frequency until a voltage from a low pass filter responsive to a signal indicative of an operating state of said first voltage controlled oscillator reaches a certain level;
• setting the switching arrangement to connect to a second voltage controlled oscillator;
• locking the phase locked loop to a start frequency close to another end of the frequency range of the transceiver;
• reducing the lock frequency until a voltage from the low pass filter, responsive to a signal indicative of an operating state of said second voltage controlled oscillator reaches a certain level;
• and
• setting a boundary frequency between both ends of the frequency range of the transceiver at which operation is changed from the first voltage controlled oscillator to the second voltage controlled oscillator.