Reflection-based radio-frequency multiplexers

1. A radio frequency multiplexer supporting a plurality of frequency bands, comprising:

a common node;

a plurality of single band nodes;

a plurality of parallel branches, wherein each parallel branch is dedicated to one of the plurality of frequency bands, wherein each parallel branch connects the common node and one of the plurality of single band nodes, and wherein a particular branch of the parallel branches comprises:

a filter configured to pass a desired frequency band through the particular branch;

a quadrature hybrid coupler coupled to the filter; and

a set of one or more other filters corresponding to one or more other frequency bands of the plurality of frequency bands, wherein the set of one or more other filters and the quadrature hybrid coupler are coupled and configured to reject the one or more other frequency bands by the particular branch.

2. The radio frequency multiplexer of claim 1 , comprising a passive network coupled to the common node and configured to further improve impedance matching.

3. The radio frequency multiplexer of claim 1 , wherein the radio frequency multiplexer comprises a triplexer.

4. The radio frequency multiplexer of claim 1 , wherein the filter and the one or more other filters comprise one or more band-pass filters.

5. The radio frequency multiplexer of claim 1 , wherein one or more of the filter and the one or more other filters comprise one or more low-pass filters.

6. The radio frequency multiplexer of claim 1 , wherein one or more of the filter and the one or more other filters comprise one or more high-pass filters.

7. The radio frequency multiplexer of claim 1 , wherein one or more of the filter and the one or more other filters are tunable or reconfigurable.

8. The radio frequency multiplexer of claim 1 , wherein one or more of the quadrature hybrid couplers are tunable or reconfigurable.

9. The radio frequency multiplexer of claim 1 , wherein one or more of the filter and the one or more other filters comprise one or more surface acoustic wave (SAW) filters.

10. The radio frequency multiplexer of claim 1 , wherein one or more of the filter and the one or more other filters comprise one or more bulk acoustic wave (BAW) filters.

11. The radio frequency multiplexer of claim 1 , wherein the radio frequency multiplexer is included in a front end of a wireless communication system that supports carrier aggregation.

12. The radio frequency multiplexer of claim 1 , wherein the radio frequency multiplexer is included in a front end of a wireless communication system that supports frequency division duplexing.

13. The radio frequency multiplexer of claim 1 , wherein the radio frequency multiplexer is included in a front end of a multiband communication system.

14. The radio frequency multiplexer of claim 1 , wherein the radio frequency multiplexer is included in a hand-held portable device that supports wireless communication.

15. The radio frequency multiplexer of claim 1 , wherein the radio frequency multiplexer is included in a base station that supports a wireless communication infrastructure.

16. The radio frequency multiplexer of claim 1 , wherein the radio frequency multiplexer is included in a repeater that supports a wireless communication infrastructure.

17. The radio frequency multiplexer of claim 1 , wherein the particular branch is configured to correspond to a transmit frequency band.

18. The radio frequency multiplexer of claim 1 , wherein one or more of the filter and the one or more other filters are realized in an acoustic domain.

19. The radio frequency multiplexer of claim 1 , wherein the particular branch is configured to correspond to a receive frequency band.

20. The radio frequency multiplexer of claim 1 , wherein the radio frequency multiplexer is included in a multi-antenna communication system.