A multiplexer for a device capable of receiving signals in first and second frequency bands, the multiplexer comprising a first branch for connecting an antenna to a first sub-system configured to process received signals in the first frequency band, a second branch for connecting the antenna to a second sub-system configured to process received signals in the second frequency band, wherein the first branch comprises a filter for attenuating received signals in the second frequency band and the second branch couples the antenna directly to the second sub-system.
1. A diplexer for a device capable of receiving signals in first and second frequency bands, the diplexer comprising:
a first branch for connecting an antenna to a first receiver sub-system configured to process signals received by the antenna in the first frequency band; and
a second branch for connecting the antenna to a second receiver sub-system configured to process signals received by the antenna in the second frequency band; wherein
the first branch comprises a filter for attenuating received signals in the second frequency band and the second branch does not include a filter, but instead couples the antenna directly to the second sub-system such that a signal received by the antenna is passed directly to the second sub-system by the second branch without any substantial attenuation other than that which occurs as a result of the signal passing through the second branch.
2. A diplexer according to claim 1 wherein the filter of the first branch comprises a diplex filter.
3. A diplexer according to claim 1 wherein the signals received by the antenna in the first frequency band are transmitted in accordance with a first telecommunications standard and the signals received by the antenna in the second frequency band are transmitted in accordance with a second telecommunications standard.
4. A diplexer according to claim 3 wherein the first telecommunications standard is GSM.
5. A diplexer according to claim 3 wherein the first telecommunications standard is Bluetooth®.
6. A diplexer according to claim 3 wherein the second telecommunications standard is GPS.
7. A receiver for a device capable of receiving signals in a plurality of frequency bands, the receiver comprising an antenna coupled to a diplexer according to claim 1 .
8. A front-end module for a receiver for a device capable of receiving signals in a plurality of frequency bands, the front-end module comprising a diplexer according to claim 1 .