| 摘要 |
PROBLEM TO BE SOLVED: To provide a PLL circuit which can correctly inspect lock-up time by a simpler constitution.SOLUTION: A PLL circuit 10 comprises at least: a voltage control oscillator 14 for generating an oscillation signal F of a frequency depending on a control voltage CV; and a loop filter 13 connected to a previous stage of the voltage control oscillator 14, for outputting the control voltage CV, in which the loop filter 13 has a resistor R1 and a capacitor C1 which are connected in series between an output line L1 of the control voltage CV and a ground. The PLL circuit 10 further comprises a lock-up determination circuit 16 for outputting a signal indicating whether a potential difference between both ends of the resistor R1 is within a preliminarily defined range.SELECTED DRAWING: Figure 1 |
