| 摘要 |
PROBLEM TO BE SOLVED: To provide a phase synchronous circuit capable of controlling the upper limit of an oscillation frequency of a voltage control oscillator.SOLUTION: VCO 150 includes a monitor voltage generation circuit 152 that generates a monitor voltage VMONI1 changing with threshold fluctuations and a ring oscillator 154 that changes an oscillation frequency according to a control voltage VCTRL2 supplied from the monitor voltage generation circuit. A VCO control circuit 104 compares the monitor voltage VMONI1 and a reference voltage VREF1 to adjust the control voltage VCTRL1. |
