THREE-FREQUENCY BRANCHING CIRCUIT, BRANCHING CIRCUIT, AND RADIO COMMUNICATION DEVICE

摘要

Conventional three-frequency branching circuits cannot be used for a system where a TDMA communication system such as the GSM or DCS and a W-CDMA communication system such as the UMTS are both adopted. A three-frequency branching circuit of the invention comprises first and second internal terminals (21, 22), an antenna terminal (20) for connection to an antenna, a branching means having a low-pass filter connected between the first internal terminal (21) and the antenna terminal (20) and a high-pass filter connected between the second internal terminal (22) and the antenna terminal (20), a switch circuit (1) for selecting either the GSM TX or the GSM RX, a switch circuit (2) for selecting one of the DCS TX, the DCS RX, and a third internal terminal (23), and an antenna duplexer connected to the third internal terminal (23).