| 摘要 |
PURPOSE: To eliminate the necessity of external parts and to display performance higher than a reference phase lock loop(PLL) by providing a PLL with both analog and digital functions in a composite digital and analog circuit provided with an analog PLL. CONSTITUTION: A 2nd phase detection part 20 detects a phase difference between a 19kHz feedback signal obtained from an analog PLL 28 and a 19kHz pilot signal included in an FM synthetic signal. The analog PLL 28 acts as a smoothing filter for a 19kHz signal D and is used for the generation of a 38kHz sine wave to be used for a signal route of an FM decoder. The signal D is turned to accurate frequency by the digital part of the analog/digital PLL and its phase noise is reduced by the analog part of the PLL. Thereby high performance capable of minimizing a phase error and attaining the accuracy of the digital PLL having no phase noise can be obtained. |
