| 摘要 |
PROBLEM TO BE SOLVED: To overcome the problem of the conventional analog PLL such that has a narrow lock range and the conventional digital PLL that has a deteriorat ed phase noise characteristic. SOLUTION: The PLL circuit provided with an analog phase comparator 1, a low pass filter 2 and a voltage controlled oscillation circuit 3, is provided with a digital phase comparator 4 and an analog switch 5, the switch 5 is connected to the digital phase comparator 4 when the voltage controlled oscillation circuit 3 is unlocked, and an output from the phase comparator 4 is given to the low pass filter 2, and the switch 5 is switched to the position of the analog phase comparator 1 when the voltage controlled oscillation circuit 3 is locked, and an output from the phase comparator 1 is given to the low pass filter 2. |
