| 摘要 |
<P>PROBLEM TO BE SOLVED: To enhance the characteristics of a duplexer employing a bulk elastic wave filter as a reception filter and a transmission filter by enhancing the degree of freedom in selecting the reception and transmission filters. <P>SOLUTION: After connecting a reception filter 11 and a phase shifter 13 in series and connecting a transmission filter 12 and a phase shifter 14 in series, the duplexer 1 connects the phase shifters 13 and 14 connected in parallel with a connection point 18 common to transmission/reception, connects the reception filter 11 with a reception port 16 not common to transmission/reception, and connects the transmission filter 12 with a transmission port 17 not common to transmission/reception. In the stop band R2 of the reception filter 11, the phase shifter 13 rotates the phase of the reception filter 11 to the open side when viewed from the connection point 18. In the stop band T2 of the transmission filter 12, the phase shifter 14 rotates the phase of the transmission filter 12 to the open side when viewed from the connection point 18. <P>COPYRIGHT: (C)2008,JPO&INPIT |
