| 摘要 |
PURPOSE:To make common use of terminals and to reduce the external terminals, by using the monitor terminal of a voltage controlled type oscillation circuit as the oscillation stop input terminal for the oscillation circuit, in an FM stereo demodulation circuit of PLL system. CONSTITUTION:To the monitor terminal P12 receiving the monitor signal which adjusts the free-run frequency of a voltage contrlled oscillation circuit VOC5 so that it is around 76kHz through the pickup of the output of a frequency dividing circuit 8, a voltage signal in excess of the monitor signal level is compulsively fed externally, allowing the oscillation stop of VOC5. Since the detection level of a voltage detection circuit 15 is set to a given voltage in excess of the monitor output level, the stop operation of VOC5 is not made with the monitor output. |
