| 摘要 |
PURPOSE:To make an objective tuning circuit independent of the other circuits with simple constitution by connecting a switching device in parallel to respective input/output terminals of plural tuning circuits having varactor diodes and applying voltages to diodes with separately provided changeover switches. CONSTITUTION:The first tuning circuit 12 and the second tuning circuit 13 are connected in parallel between an input terminal 1 and an output terminal 10 of a tuning switching device. Varactor diodes 5a and 5b connected in series to coupling capacitors 4a and 4b are provided in tuning circuits 12 and 13 individually. Changeover switches 9a and 9b are connected to diodes 5a and 5b, and a tuning voltage applying terminal 11 is connected to switches 9a and 9b. The tuning voltage is switched and applied to diodes 5a and 5b in tuning circuits 12 and 13 to make the objective tuning circuit independent of the other tuning circuit, and thus, the constitution of the device is simplified. |
