| 摘要 |
PROBLEM TO BE SOLVED: To provide additional circuity for suppressing an insertion loss of a signal path, preventing electrostatic discharge and securing robustness. SOLUTION: A duplexer for connection with an antenna comprises an antenna port, a transmitting filter comprising bulk acoustic wave (BAW) resonators having a first antenna side impedance coupled with the antenna port, a receiving filter comprising BAW resonators having a second antenna side impedance coupled with the antenna port, and a shunt inductance coupled between the antenna port and ground. The shunt inductance and the first and second antenna side impedances of the transmitting filter and the receiving filter are selected in such a way that the shunt inductance turns the first and second input impedances in a negative direction in a Smith diagram. COPYRIGHT: (C)2007,JPO&INPIT
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