FREQUENCY SYNTHESIZER, RADIO COMMUNICATION SYSTEM USING IT, AND CONTROL METHOD OF FREQUENCY SYNTHESIZER

摘要

PROBLEM TO BE SOLVED: To provide a frequency synthesizer which has a good C/N characteristic and integrates a voltage-controlled oscillator (VCO) with a wide output frequency range at a low cost.;SOLUTION: The frequency synthesizer is provided with the VCO (1) having a plurality of frequency bands, stores its prescribed voltage (V1) in a storage circuit (11) by measuring an oscillation frequency of each band in a state of being applied to the VCO (1), compares frequency division ratio setting given from a PLL control circuit (14) with a measured value of the stored frequency, selects one band from the VCO (1) based on the comparison result, further oscillates the VCO (1) at a fixed voltage on the selected band, and decides the frequency band used actually for a frequency phase lock from the oscillation frequency obtained at that time and from an error between the oscillation frequency and a reference frequency.;COPYRIGHT: (C)2005,JPO&NCIPI