| 摘要 |
PURPOSE: An up-converter apparatus for a CDMA(Code Division Multiple Access) system is provided to receive 3 channels using one up-converter and quickly embody a mass data service. CONSTITUTION: A digital modulating unit has three filter/QPSK modulating units(10,12,14) for filtering baseband signals received from a channel card, an adder(16) for adding 3FA(Frequency Assignment) signals modulated in the filter/QPSK modulating units(10,12,14), and a DAC(Digital to Analog Converter)(18). An RF(Radio Frequency) up-converter unit(20) comprises the first mixer(21) for mixing the 3FA signal through a low pass filter with a local frequency from a PPL, the first BPF(Band Pass Filter)(22) for filtering the mixed frequency signal, the second mixer(23) for the signal filtered by the first BPF(22) with a variable frequency signal, and the second BPF(24) for filtering a harmony component and a spurious component generated in a wide band. An LNA(Low Noise Amplifier)(25) receives the signal from the up-converter unit(20). |
