| 摘要 |
A PLL circuit includes: a phase comparator (2) for comparing the phase of an input signal with the phase of a reference input signal to output a signal according to the phase difference therebetween; a low pass filter (4, 6) for outputting a low frequency control voltage on the basis of the output of the phase comparator; a voltage control oscillator (14) for controlling an oscillating frequency on the basis of the control voltage; and a characteristic control part (8, 10, 12) for controlling the characteristic of oscillating frequency to control voltage of the voltage control oscillator on the basis of n+1 ranges of first through n+1-th ranges obtained by dividing a variable range of the control voltage by first through n-th (n >/= 2) thresholds which are different from each other. Thus, it is possible to widen the operating frequency range, and it is possible to inhibit the frequency variation due to noises. <IMAGE> |
