FRACTIONAL-N SYSTEM PHASE SYNCHRONIZATION LOOP FREQUENCY SYNTHESIZER

摘要

PROBLEM TO BE SOLVED: To achieve a suppression of spurious occurring at an F-N system PLL frequency synthesizer output owing to nonlinearity of a detection voltage characteristic to a phase difference of a phase comparator.;SOLUTION: A fractional-N system phase synchronization loop frequency synthesizer has a voltage controlled oscillator generating high frequency signals, a variable frequency divider generating a synchronization signal from the high frequency signal, a reference oscillation source generating a reference signal, a reference signal generation means generating two reference signals having a phase difference from the reference signal, a first phase comparator inputting the respective reference signals and the synchronization signal and outputting the first and the second phase comparison signals, a second phase comparator outputting the third and the fourth phase comparison signal, and a loop filter synthesizing a difference result of the first and the second phase comparison signals and a difference result of the third and the fourth phase comparison signals and outputting a synthesized signal smoothed, wherein the high frequency signal is generated by controlling the voltage controlled oscillator according to the synthesized signal.;COPYRIGHT: (C)2009,JPO&INPIT