| 摘要 |
PURPOSE: A terminal for use in DCS(Digital Cellular System) and PCS(Personal Communication Service) is provided to enable a terminal to be used in both DCS and PCS by using a duplexer having transceiving function and a VCO(Voltage Control Oscillator) generating different local signals using a switching circuit. CONSTITUTION: In the case of DCS, a signal in baseband and a signal from TCXO (Temperature Controlled crystal Oscillator) are mixed in a mixer to generate an intermediate frequency signal. Then, a separating part in a DCS operating part provides the first local signal outputted from the first VOC in a switching VOC to each of mixers. At this time, the first and the second transistors(Q1,Q2) are turned on and the third and the forth transistors(Q3,Q4) are turned off. Thus, the first local signal for DSC is generated and is provided to the mixer to produce a transmit frequency signal. In the case of PCS, the firs and the second transistors(Q1,Q2) are turned off and the third and the forth transistors(Q3,Q4) are turned on. Thus, the second VOC(VOC2) is operated and the second local signal for PCS is generated. The second local signal is provided to a mixer to produce a transmit frequency signal for use in PCS.
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