| 摘要 |
PURPOSE: A transceiver of communication terminal for dual band/tri mode is provided to change IF frequencies of PCS type and CDMA, AMPS types, used in a reception side, into IF frequencies having same frequency band and change IF frequencies of PCS type and CDMA, AMPS types used in a transmission side into IF frequencies other frequency bands each other, thereby simplifying the circuit design. CONSTITUTION: A diplexer(11) combines a PCS(Personal Communication Service) duplexer and CDMA(Code Division Multiple Access), AMPS(Advanced Mobile Phone) duplexer for operating according to PCS type or CDMA, AMPS types, respectively. A PCS duplexer(12) charges a transmission/reception of a signal by PCS type. A CDMA/ AMPS duplexer(13) charges a transmission/reception of a signal by CDMA/AMPS type. The first and the second LNA(Low Noise Amplifier)(21,22) amplify each RF frequency received from the PCS duplexer(12) and CDMA/AMPS duplexer(13). The first and the second RF SAW(Surface Acoustic Wave) filter(23,24) remove the noise of each RF frequency amplified from the first and second LNAs(21,22). The first mixer(31) mixes RF frequency with PCS local frequency and then outputs an IF frequency of 183.6MHz band. The second mixer(32) mixes RF frequency with CDMA/AMPS local frequency and then outputs an IF frequency of 183.6MHz band. The third mixer(33) mixes RF frequency with CDMA/AMPS local frequency and then outputs an IF frequency of 183.6MHz band. The first switch(34) switches IF frequencies of PCS type and CDMA type. The first IF BPF(35) passes the IF frequency inputted through the switch(34) by a bandwidth-limited operation. The second IF BPF(36) passes the IF frequency of AMPS type by bandwidth-limited operation. An IFR(Intermediate Frequency Receiver)(37) receives and processes the IF frequency transmitting the first and second IF BPFs(35,36).
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