TEMPERATURE COMPENSATION IN A PHASE-LOCKED LOOP

摘要

An integrated circuit comprises a digital phase-locked loop (200) for a wireless communications unit. The digital phase-locked loop (200) comprises a voltage controlled oscillator (220) and a digital tuning subsystem (240). An input of the digital tuning subsystem (240) receives the output signal from the voltage controlled oscillator (220), and an output of the digital tuning subsystem (240) is supplied to the voltage controlled oscillator (220). A digital voltage generator (260) is adapted to store at least two predetermined forcing voltages (Vf1...Vfn). The digital voltage generator (260) is adapted to select one of the at least two predetermined forcing voltages (Vf1...Vfn), in dependence on a current temperature value (T), and to supply it as a forcing voltage (Vf) to an input of the voltage controlled oscillator (220), prior to the phase locked loop (200) achieving lock. A wireless communication unit and a method of tuning a phase-locked loop are also provided.