Patent ID: 6411820
Filing Date: 2002-06-25
Classification: H03L

Abstract:
A dual-mode wireless telephone having a phase lock loop (PLL) with two selectable bands of operating frequencies, the dual-mode wireless telephone comprising:a mixer which receives a local oscillator signal and an output signal, the mixer generating a delta signal of a first frequency; a phase comparator which compares the delta signal of the first frequency with an intermediate signal of a second frequency, the phase comparator generating an UP signal and a DOWN signal based on the results of the comparison; a switch having a first output and a second output which receives the UP signal and the DOWN signal, wherein the switch outputs the UP signal on the first output and the DOWN signal on the second output when the switch is in a first position in which the PLL causes the dual-mode wireless telephone to operate in a first mode, and the switch outputs the UP signal on the second output and the DOWN signal on the first output when the switch is in a second position in which the PLL causes the dual-mode wireless telephone to operate in a second mode; a signal generator which converts the UP signal and the DOWN signal into a control signal; and a voltage controlled oscillator which receives the control signal and adjusts the output signal based on the control signal.