| 摘要 |
PURPOSE:To prevent the occurrence of frequency variance at the time of frequency switching to shorten the output switching time by resetting a variable frequency dividing circuit so that the phase difference between the output signal of the variable frequency dividing circuit and a reference signal is about 0 at the time of frequency switching. CONSTITUTION:At the time of frequency switching, a setting circuit 7 sends a loop control signal to open a loop switch 10 and sets frequency division data corresponding to a desired frequency to a variable frequency dividing circuit 2. Simultaneously, the circuit 7 sends a reset signal to the variable frequency dividing circuit 2 with the reference signal as the trigger and sends a loop control signal to close the loop thereafter and equalizes the output signal phase of the variable frequency dividing circuit 2 and the reference signal phase to each other. Consequently, the frequency variance for frequency switching is eliminated. Thus, the output switching time is shortened. |
