| 摘要 |
PROBLEM TO BE SOLVED: To make a dual PLL synthesizer small in size and low in cost. SOLUTION: Two frequency synthesizers 1a and 1b for changing over the channel of a high frequency signal to be outputted are provided. Attenuators 2a and 2b, amplifiers 3a and 3b, attenuators 4a and 4b, amplifiers 5a and 5b and a switch circuit 7 are connected to the post-stages of the frequency synthesizers 1a and 1b. A channel switch circuit 9 changes over the turning on/off of the amplifiers 3a and 3b and the amplifiers 5a and 5b and the switch circuit 7. Large isolation is secured between the frequency synthesizers 1a and 1b and the switch circuit 7 of the post-stage by the attenuators 2a and 2b and the amplifiers 3a, 3b, 5a and 5b, and isolation between two systems is achieved. |
