| 摘要 |
PURPOSE: A transceiver of communication terminal for dual band/tri mode is provided to change IF frequencies, 85.38MHz band of CDMA and AMPLS types and 210.38MHz band of PCS type, used a reception side, into 183.6MHz band equally and change an IF frequency of 130.38MHz band used in a transmission side into 228.6MHz band of CDMA,AMPS types and 103.6MHz band of PSC type, thereby removing one filter among three IF SAW filters and simplifying the circuit design. CONSTITUTION: A dual PLL module(21) generates CDMA and AMPS local frequency of 1052.6-1077.6MHz band and PCS local frequency of 1746.4-1806.4 MHz band, respectively. A first mixer(22) mixes RF frequency with CDMA and AMPS local frequencies and then outputs an IF frequency of 183.6MHz band. A second mixer(23) mixes RF frequency and PCS local frequency and then outputs an IF frequency of 183.6MHz band. A first switch(24) switches IF frequencies of PCS type and CDMA type. A first IF SAW filter(25) passes the IF frequency transmitted from the first mixer(22). A second IF SAW filter(26) passes the IF frequencies of PCS type and CDMA type. An IFR(Intermediate Frequency Receiver)(27) receives and processes the IF frequency transmitted through the first and second IF SAW filters(25,26).
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