| 摘要 |
A saw duplexer is provided to prevent damage due to an impulse signal such as an ESD(ElectroStatic Discharge) by forming a coupling transmission line with two transmission lines. A saw duplexer includes transmission and reception filters(41,42) positioned among an antenna terminal, a transmission terminal, and a reception terminal to filter signals of different frequency bands without mutual interference, and a phase shifter for matching impedance between the transmission and reception filters(41,42). The phase shifter includes a first capacitor pattern(21) connected electrically to the transmission filter(41) and the antenna terminal, a second capacitor pattern(22) connected electrically to the reception filter(42), a ground pattern(23) formed apart from the first and second capacitor patterns(21,22), and first and second transmission lines(25,26) for respectively connecting the first and the second capacitor patterns(21,22) to the ground pattern(23). A coupling transmission line is formed by coupling the first and second transmission lines(25,26) to each other in the same interval. |
