| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device which can cope with frequency change in a wide band and for can output frequencies with a little jitter. SOLUTION: The output of a low pass filter is inputted to a variable resistor 112 for frequency fine adjustment, a variable resistor 113 for frequency band adjustment, a capacitor 114 for frequency band adjustment, and a capacitor 115 for voltage holding. In the asynchronization, a switch 117 is turned on. Output frequencies are changed in a wide frequency band by the variation of the valiable resistances 112 and 13 and the capacitance 114. Afterwards, a switch 117 is turned off in a synchronizing state. Then, an output voltage in the synchronization is preserved in capacitor 115, and the output frequencies are changed in a narrow frequency band by the change on only the variable resistance 112 with the frequencies in the synchronization as a center. Therefore, it is possible to realize the PLL for coping with frequency change in a wide band in the asynchronization and for obtaining output frequencies with a little jitter in the synchronization. |
