| 摘要 |
PURPOSE: A down-converter using wideband and narrow band channel filters is provided to receive a narrow band signal and a wideband signal and convert the narrow band signal and the wideband signal into a baseband signal. CONSTITUTION: A band pass filter(100) receives an RF(Radio Frequency) signal transmitted from a terminal through an FEU(Front End Unit) and passes only signal in a desired band. A mixer(200) receives the RF signal filtered through the band pass filter(100), and mixes the received RF signal with a local oscillation frequency for converting the RF signal into an IF(Intermediate Frequency) signal. The first channel filter(300) receives the IF signal from the mixer(200) and passes only desired narrow band among the IF signal. The second channel filter(400) receives the IF signal from the mixer(200) and passes only desired wideband among the IF signal. An IF amplifier(500) receives the IF signal from the first channel filter(300) or the second channel filter(400), amplifies the received IF signal, and outputs the amplified IF signal to a rear end block. A control unit(600) outputs a wideband or narrow band selection signal when a wideband/narrow band selection control signal is received through an operator terminal by an operator. The first switch(700) connects to the mixer(200), the first and second channel filters(300,400), receives the wideband or narrow band selection control signal from the control unit(600), and is switched to a channel filter corresponding to the received wideband or narrow band selection control signal. The second switch(800) is simultaneously operated with the first switch(700), connects between the first and second channel filters(300,400) and the IF amplifier(500), receives the wideband or narrow band selection control signal from the control unit(600), and is switched to a channel filter corresponding to the received wideband or narrow band selection control signal.
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