PHASE LOCKED LOOP BY USING DUAL LOOP FILTER FOR DIGITALIZED RF COMMUNICATION SYSTEM

摘要

The present invention relates to a double loop filter phase locked loop circuit for a digital wireless communication system. The dual loop filter phase locked loop circuit of the present digital wireless communication system having a voltage controlled oscillator and a loop filter is connected between a phase detector, one output terminal of the phase detector, and an input terminal of the loop filter to form a broadband loop. A phase-synchronized loop frequency synthesizer having an internal charge pump, and coupled between the first and second phase detectors of the phase detector and an input terminal of the loop filter, to form a narrow band loop to form the first and second phases. And an external charge pump which reduces the amount of current output to the detection terminal to reduce the amount of current provided to the loop filter.