| 摘要 |
The invention relates to an antenna changeover switch for transceivers in a mobile station, designed for operation in at least two discrete HF transmission bands. For this purpose diode switches (D1 to D4) with HF impedance transformers are often used, which switch between channels of the GSM 900 network and channels of the DCS 1800 network. Owing to inadequate decoupling between the transceivers an appreciable portion of the transmitting signal from the active transceiver (TX1 or TX2) will arrive at the antenna terminal of the inactive transceiver. Therein in particular a portion coupled into the antenna terminal (A2) of the DCS 1800 transceiver by the GSM 900 transceiver can be so large that the currentless semiconductor components connected there generate harmonic waves. The problem is solved according to the invention in that controls (S1, S2) simultaneously conductively control the switch diodes (D1 and D2) in the GSM 900 transceiver and a switch diode (D4) located parallel to the signal input of the receiving unit (RX2) in the other transceiver with a bias current.
|
