Patent ID: 7190236

Claim:
An apparatus for oscillating a frequency, comprising: frequency. a phase-locked loop circuit which generates a first frequency signal; a variable frequency divider which divides the first frequency signal by a division ratio to generate a second frequency signal that lies within a predetermined frequency band, a first detector in the phase-locked loop circuit to compare a first reference frequency signal and the second frequency signal; a second detector to compare a second reference frequency signal and at least a third frequency signal; a first controller to control the division ratio of the variable frequency divider based on a result of the comparison of the second reference frequency signal and at least the third frequency signal performed by the second detector; and a second controller to adjust a voltage-controlled oscillator of the phase-locked loop circuit to control the first frequency signal, wherein the first controller varies the second frequency signal by a first amount and the second controller varies the second frequency signal by a second amount to cause the second frequency signal to lie within said predetermined frequency band.