WIRELESS COMMUNICATION UNIT, INTEGRATED CIRCUIT COMPRISING A VOLTAGE CONTROLLED OSCILLATOR AND METHOD OF OPERATION THEREFOR

A wireless communication unit comprises a frequency generation circuit employing a phase locked loop (PLL) circuit comprising a voltage controlled oscillator having a modulation port for directly modulating a signal output from the voltage controlled oscillator. The voltage controlled oscillator is operably coupled to at least one switch and a capacitor bank comprising one or more varactors. A controller is arranged to switch in one or more varactors associated with the modulation port of the phase locked loop circuit to provide an inverse cubic relationship to the direct modulated signal. In addition, or alternatively, the phase locked loop (PLL) circuit may comprise a voltage controlled oscillator having a tuning port for controlling a frequency of a signal output from the voltage controlled oscillator. The controller here is arranged to switch in one or more varactors associated with the tuning port of the phase locked loop circuit in an inverse square relationship.