| 摘要 |
In a tuning circuit apparatus comprising first and second tuning circuits having their tuning frequencies varied in a ganged fashion; a composite varactor device provides first and second Varicap diodes formed on a common semiconductor substrate, with anodes of the first and second Varicap diodes being led out to respective independent terminals and cathodes of the Varicap diodes being led out to a common terminal, first and second tuning coils are connected at first ends thereof to the independent terminals associated with the first and second Varicap diodes, respectively, first and second by-pass capacitors are respectively connected between second ends of the first and second tuning coils and the common terminal of the composite varactor device, and a control voltage supplying source parallelly supplies a control voltage to the first and second Varicap diodes.
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