PHASE LOCKED LOOP ENABLING GENERATION OF REFERENCE SIGNAL HAVING HIGH SPECTRAL PURITY

摘要

PROBLEM TO BE SOLVED: To improve parasitic phase noise of a phase-locked loop. SOLUTION: This loop is provided with a VCO (OSC) generating an output signal (Vlo), a frequency divider(DIV) to which an output of the VCO is inputted, a phase/frequency detector (CP) comparing an output signal (Vdiv) of the frequency divider with the frequency of a comparison signal (Vcomp) and supplying a tuning signal the VCO, and a correcting means (PMOD) for detecting parasitic phase modulation included in the output signal Vlo of the VCO and adding phase modulation which is similar to the parasitic phase modulation to the comparison signal.