| 摘要 |
PURPOSE: An apparatus for performing a frequency down converting of a CDMA(Code Division Multiple Access) mobile communication system is provided to construct a 1.25MHz frequency down converter and a 3.75MHz frequency down converter as one frequency down converting board, by using a switch and a pad. CONSTITUTION: The first/second filters(16,24,33,34) are composed in parallel to each other, and filter received RF signals with different optional bandwidths. The first switches(35,36) switch the RF signals to the first filters(16,24) or the second filters(33,34), according to a band selection control signal. The second switches(35a,36a) transmit the filtered RF signals to a baseband. An attenuation compensator(37) is mounted on a front end of one of the filters(16,24,33,34) having small gains, and compensates the filters having the small gains, to make the first and the second filters(16,24,33,34) have same gains. A frequency down converter performs a frequency down converting for RF signals having optional bandwidths from the second switches(35a,36a) into IF signals.
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