| 摘要 |
PROBLEM TO BE SOLVED: To reduce the level of either double harmonic outputted from two voltage-controlled oscillators when being outputted from a buffer amplifier. SOLUTION: The two-band oscillator comprises a first voltage-controlled oscillator 1 that oscillates at a first frequency band, a second voltage-controlled oscillator 2 that oscillates at a second frequency band that is higher than the first frequency band, and a buffer amplifier 3 that selectively amplifies an oscillation signal outputted from the first voltage-controlled oscillator or an oscillation signal outputted from the second voltage-controlled oscillator 2, and at the same time has characteristics where the gain is attenuated at nearly double the frequency band of the second frequency band. A coupling circuit 1i for inputting the oscillation signal of the first voltage-controlled oscillator 1 to the buffer amplifier 3, and a trapping means 1j are inserted between the output end of the first voltage-controlled oscillator 1 and the input end of the buffer amplifier 3, thus attenuating nearly double the frequency band of the first frequency band by the trapping means 1j.
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