| 摘要 |
PURPOSE:To enable to obtain the reference signal of nonmodulation up to a low- frequency band, by a cascade connection of the 1st PLL using an analog phase comparator and the 2nd PLL using a digital phase comparator. CONSTITUTION:An input modulation signal is applied to the 1st PLL 20 having broader loop band width consisting of an analog phase comparator 22, and an output of the 1st PLL 20 is applied to the 2nd PLL 30 having narrow loop band width consisting of a digital phase comparator 32 in cascade connection, nonmodulation carrier is obtained as an output. Thus, since the analog phase comparator 22 is strong against noise and capture range is wider for digital phase comparator 32, the reference signal with nonmodulation up to a low-frequency band while having stability against noise and a certain degree of capture range, can be obtained. |
