Patent ID: 7545847

Claim:
A frequency synthesizer applied to a frequency hopping system comprising: a voltage controlled oscillator (VCO) for generating an oscillating frequency according to a voltage control signal; a phase lock loop system comprising a first frequency divider, the phase lock loop system being used for dividing the oscillating frequency by a first even number with the first frequency divider to generate a first dividing signal and generating the voltage control signal according to the first dividing signal; a second frequency divider connecting to the VCO, for dividing the oscillating frequency by a second even number to generate a second dividing signal and a third dividing signal; a first single-side-band mixer (SSB mixer) connecting to the second frequency divider, for mixing the second dividing signal and the third dividing signal to generate a first mixing signal; a second SSB mixer connecting to the phase lock loop system and the first SSB mixer, for mixing the first mixing signal and the first dividing signal to generate a second mixing signal according to a first band selection signal; and a multiplexer connecting to the first SSB mixer and the second SSB mixer, for selecting the first mixing signal or the second mixing signal to output according to a second band selection signal.