| 摘要 |
In a multi-band radio terminal apparatus, when communication frequency bands are switched, a reception intermediate frequency is selected to be equal to each other in respective communication frequency bands. As a result, the circuit arrangements of this multi-band radio terminal apparatus succeeding to the intermediate frequency signal circuit stage are commonly used in the respective communication frequency bands. While a local oscillator signal is produced by a voltage-controlled oscillator, a phase-locked loop, and a doubler, in a case where communication is established within a plurality of communication frequency bands, the transmission/reception frequency intervals are different from each other. A mixer for a reception system and a mixer for a transmission system are commonly used so as to convert the frequency of the local oscillator signal into a frequency existing between the communication frequency and the intermediate frequency.
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