Patent ID: 8653860

Claim:
A frequency synthesizer comprising: a voltage-controlled oscillator; a frequency divider which divides a frequency signal output from the voltage controlled oscillator; an integrated waveform generating unit receiving a digital signal having a digital value that depends on a set frequency and integrating the digital value to generate a saw-tooth wave having a saw-tooth shaped integrated waveform in which a negative value and a positive value are combined; an edge detecting unit detecting a rising edge or a falling edge of a frequency signal output from the frequency divider to output a rectangular wave signal that depends on a frequency of the frequency signal; a latched circuit latching a value of the saw-tooth wave generated by the integrated waveform generating unit, in response to the rectangular wave signal; a loop filter integrating the value of the saw-tooth wave latched by the latched circuit; and a digital/analog converting unit digital/analog-converting an output of the loop filter to output a resultant to the voltage-controlled oscillator.