| 摘要 |
PURPOSE: A method for transmitting an IF(Intermediate Frequency) in a mobile communication base station device using a CDMA system is provided to digitally receive baseband I/Q(Inphase/Quadrature) signals to convert the signals into analog signals, and to perform the first I/Q modulations and up-converting processes for the analog signals to 21.4MHz, then to perform the second up-converting process for the signals to 70MHz IFs. CONSTITUTION: D/A converters(30,30a,38) convert I/Q(Inphase/Quadrature) digital signals into analog signals having optional basebands. The first IF(Intermediate Frequency) converter performs I/Q modulations and up-converting processes for the analog signals according to a local frequency. The second IF converter mixes an up-converted IF signal with the local frequency and other local frequency, and up-converts the mixed signal to an optional IF signal. A transmitter transmits the up-converted signal to an RF processor. The first IF converter comprises as follows. Amplifiers(31,31a,39,42) amplify the analog I/Q baseband signals. Filters(32,32a,36,41) remove spurious signal components except the amplified I/Q baseband signals. A modulator(34) modulates spurious signal components-removed I/Q signals, and performs the first up-converting to an optional IF signal, by the local frequency. PLLs(Phase Locked Loops)(35,35a) supply the local frequencies.
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