PHASE LOCKED LOOP AND METHOD OF OPERATING PHASE LOCKED LOOP

摘要

A phase locked loop and a method for operating the same are provided to reduce an area thereof by sharing a charge pump in a receiving phase locked loop and a transmitting phase locked loop. A first voltage controlled oscillator(222) is connected to a first loop filter(221). A second voltage controlled oscillator(232) is connected to a second loop filter(231). A first switching circuit(211) outputs a feedback signal outputted from the first voltage controlled oscillator or a feedback signal outputted from the second voltage controlled oscillator in response to a switching control signal. A phase detector(212) receives a reference signal and an output signal of the first switching circuit and generates a control signal corresponding to a phase difference between the received signals. A charge pump(213) is connected to the phase detector. A second switching circuit(214) is formed to connect an output terminal of the charge pump with an input terminal of the first loop filter or an input terminal of the second loop filter in response to the switching control signal.