| 摘要 |
PURPOSE:To decrease the number of IC peripheral parts by superposing the phase detection output of an APC loop and the frequency detection output of an AFC loop on each other by one detection filter. CONSTITUTION:The detection output of a phase detector 8 in an APC loop is supplied to one input terminal of a detection filter 22. The frequency detection output of a frequency discriminating circuit 13 in an AFC loop, on the other hand, is supplied to the other input terminal of the detection filter 22. Both the detection outputs are superposed on each other by one detection filter and a VCO15 is controlled by the resulting signal. Consequently, the operations of three conventionally required parts, i.e., a loop filter, an adder and an LPF are performed by only one detection filter 22, so that the number of external IC parts is decreased. |
