| 摘要 |
PROBLEM TO BE SOLVED: To reduce systems of an RF-local VCO and a means for stabilizing its frequency to be one system in a dual band transmission system. SOLUTION: A second mixer 3 is inserted between a phase comparator 1 and a mixer 2 for executing frequency-conversion (down conversion) by an RF-local frequency fLO1 which in linked with a desired transmission frequency. Moreover, it is converted into a final comparison frequency fREF1 by the second mixer 3 so as to constitute a PLL loop. A second local signal generator 8 is disposed as a local signal source to the second mixer 3. Thus, the RF-local signal generator for selecting a transmission frequency is made to be one system and the local signal frequency of the second mixer 3 is combined so that a transmission frequency band is selected. |
