Patent ID: 8373469
Filing Date: 2013-02-12
Classification: H03L

Abstract:
1. A phase-locked loop based frequency synthesizer comprising: a voltage controlled oscillator for controlling an output frequency by a control voltage; a multi-signal generator that uses an input reference signal to generate a plurality of output reference signals having the same frequency as and a different phase from that of the input reference signal by the input reference signal; a fractional frequency divider for dividing the output frequency and outputting the same; a pulse generator that uses a signal having a frequency divided by the fractional frequency divider to generate a plurality of comparison signals each having a comparison frequency lower than the divided frequency; a plurality of phase frequency detectors for outputting a pulse signal according to differences in phase and frequency between the plurality of output reference signals and the comparison signals; a plurality of charge pumps for generating a control current corresponding to the pulse signal of the phase frequency detectors; and a loop filter for generating the control voltage from the control current generated by the plurality of charge pumps and outputting the same to the voltage controlled oscillator, wherein the plurality of output reference signals respectively corresponds to a plurality of signals obtained by dividing one period of the input reference signal by a plurality of phases.