Patent ID: 7511581

Claim:
A frequency synthesizer, comprising: A frequency/phase detector for comparing a frequency and phase of a reference high frequency signal with a frequency and phase of a feedback high-frequency signal; a charge pump for producing an output current corresponding to the result of the comparison performed by the frequency/phase detector; a loop filter for producing an output voltage corresponding to an accumulated value of the output current of the charge pump; a voltage-controlled oscillator for generating an oscillation signal having a frequency corresponding to the output voltage of the loop filter; and a variable frequency divider for dividing an output signal of the voltage controlled oscillator by a designated integer value and outputting the result as a feedback signal, wherein the variable frequency divider comprises: a prescaler for selecting one of a plurality of dual divisor value sets according to an external frequency selection signal; a main counter for counting the number of output pulses of the prescaler; and a swallow counter for designating an interval divided by a specific divisor value of the dual divisor value sets; and wherein at leas(e)t two of an amount of unit pumping charges of the charge pump, a(n) RLC value of the loop filter, a(n) RLC value of the voltage-controlled oscillator, and a divisor value of the variable frequency divider are controlled according to a band.