| 摘要 |
A multiband mobile unit communication apparatus is disclosed which comprises: antennas for receiving plural radio wave SIGs respectively transmitted from plural mobile unit communication systems, said plurality of radio wave SIGs having different carrier frequencies respectively; independent CKTs for generating IF SIBs from said radio wave SIGs from said antennas respectively; and a common CKT including a switch according to a mode SIG, a quadrature demodulation CKT for directly converting the IF SIG from the switch into I and Q baseband SIGs, and a decoding CKT for outputting a decoding result from said I and Q baseband SIGs. In accordance with the mode SIG, a power is selectively supplied to the independent CKTs, a switchable FRQ-divider may be provided to FRQ-dividing a LO SIG for the quadrature demodulation CKT, a switchable tuning CKT may by provided to the variable gain amplifying CKT to provide a switchable tuning FRQ, a switchable low-pass filters may be provided to switchably low-pass-filtering the I and Q baseband SIGs. The variable gain amplifier may be an analog type or a digital type. An antenna diversity receiving may be provided.
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