| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the change of the charging/discharging current that occurs when the frequency is pulled in and to shorten the frequency pull-in time by providing a drive stopping circuit to stop the driving of a constant current source circuit that is required for pulling in a phase in a frequency pull-in mode. SOLUTION: A drive stopping circuit 7 is provided between a phase comparator 1 and a constant current source circuit 2. The circuit 7 functions to cut the output signals of the comparator 1 (drive signals of the circuit 2) P1 and P2, not to output them to the circuit 2 and accordingly to stop the driving of the circuit 2 as long as a drive signal F1 or F2 of a constant current source circuit 4 is outputted from a frequency comparator 3. When both signals F1 and F2 are not outputted from the comparator 3, the signals P1 and P2 of the comparator 3 are transmitted and outputted to the circuit 2. |
