Duplexer

Abstract

A duplexer is provided. The duplexer includes a first band pass filter (BPF) coupled to a first signal port and a second signal port; and a second BPF coupled to the first signal port and a third signal port, each of the first BPF and the second BPF including a first resonance circuit which comprises a plurality of first resonators coupled in series; a second resonance circuit which comprises a plurality of second resonators coupled in series; and a third resonance circuit which comprises a plurality of third resonators coupled in parallel and formed in divided lines coupling the first and second resonance circuits.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The above and/or other aspects of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawing figures, wherein;

FIG. 1 is a simplified block diagram of a duplexer according to an exemplary embodiment of the present invention;

FIG. 2 is a cross-sectional view of an FBAR according to an exemplary embodiment of the present invention;

FIG. 3 is a simplified block diagram of first and second BPFs of FIG. 1;

FIG. 4 is a block diagram of an exemplary first BPF of FIG. 1;

FIG. 5 is a graph showing a simulation result of filtering characteristic of the first BPF of FIG. 4;

FIG. 6 is a block diagram of another exemplary embodiment of the first BPF of FIG. 1;

FIG. 7 is a block diagram of an exemplary embodiment of the second BPF of FIG. 1;

FIG. 8 is a graph showing a simulation result of filtering characteristic of the second BPF of FIG. 7;

FIG. 9 is a diagram showing impedance characteristic of the second BPF to the first BPF of FIG. 1;

FIG. 10 is a block diagram of a duplexer constructed as a single chip set according to an exemplary embodiment of the present invention;

FIG. 11 is a block diagram of a related art duplexer constructed using a plurality of FBARs;

FIG. 12 is a diagram showing a function of the phase shifter of FIG. 11; and

FIG. 13 is another diagram showing a function of the phase shifter of FIG. 11.

Claims

1. A duplexer comprising: a first band pass filter (BPF) coupled to a first signal port and a second signal port; anda second BPF coupled to the first signal port and a third signal port,each of the first BPF and the second BPF comprising: a first resonance circuit which comprises a plurality of first resonators coupled in series;a second resonance circuit which comprises a plurality of second resonators coupled in series; anda third resonance circuit which comprises a plurality of third resonators coupled in parallel and formed in divided lines coupling the first and second resonance circuits.

2. The duplexer as in claim 1, wherein the first, second, and third resonators are film bulk acoustic resonators (FBARs).

3. The duplexer as in claim 1, wherein the first and second BPFs filter signals of first and second frequency bands, respectively, the second BPF is in a line-open state in the first frequency band, and the first BPF is in a line-open state in the second frequency band.

4. The duplexer as in claim 1, wherein the first resonance circuit of the first BPF is coupled between the first signal port and the second signal port, and the first resonance circuit of the second BPF is coupled between the first signal port and the third signal port.

5. The duplexer as in claim 1, wherein both ends of the second resonance circuit of each of the first and second BPFs are coupled to ground.

6. The duplexer as in claim 5, wherein, in the second resonance circuit of the first BPF, a node of a plurality of nodes between the second resonators is connected to ground.

7. The duplexer as in claim 6, wherein, in the second resonance circuit of the first BPF, only one node of the plurality of nodes between the second resonators is connected to the ground.

8. The duplexer as in claim 5, wherein the first BPF further comprises inductors coupled to the second resonance circuit and ground.

9. The duplexer as in claim 5, wherein the first BPF further comprises an inductor coupled in parallel to a front-end first resonator and an inductor coupled in parallel to a back-end first resonator of the plurality of first resonators of the first resonance circuit.

10. The duplexer as in claim 5, wherein the first and second resonators of the first BPF are arranged to face each other, and the divided lines couple together the facing first and second resonators.

11. The duplexer as in claim 10, wherein the first and second resonators of the second BPF are arranged to face each other, a first divided line couples a front-end node of the first resonator with a back-end node of the second resonator, and a second divided line couples a back-end node of the first resonator with a front-end node of the second resonator.

12. The duplexer as in claim 11, wherein the second BPF further comprises a plurality of fourth resonators coupled between the first signal port and the first resonance circuit and between the second signal port and the first resonance circuit, respectively.

13. The duplexer as in claim 12, wherein the second BPF further comprises an inductor which is coupled in parallel to the fourth resonator coupled between the first signal port and the first resonance circuit.

14. The duplexer as in claim 11, wherein the second BPF further comprises an inductor coupled between the back end node of the second resonance circuit and ground.

15. A duplexer comprising: a first band pass filter (BPF) which is coupled to a first signal port and a second signal port; anda second BPF which is coupled to the first signal port and a third signal port,wherein a frequency band of a signal passed by the first BPF is suppressed by the second BPF without using a phase shifter.

16. The duplexer as in claim 15, wherein a frequency band of a second signal passed by the second BPF is suppressed by the first BPF without using a phase shifter.

17. The duplexer as in claim 15, wherein the second BPF suppresses the signal by about 40 dB.

18. The duplexer as in claim 16, wherein the second BPF suppresses the signal by about 40 dB, and the first BPF suppresses the second signal by about 40 dB.

19. The duplexer as in claim 15, wherein each of the first BPF and the second BPF comprises: a first resonance circuit which comprises a plurality of first resonators coupled in series;a second resonance circuit which comprises a plurality of second resonators coupled in series; anda third resonance circuit which comprises a plurality of third resonators coupled in parallel and formed in divided lines coupling the first and second resonance circuits.

20. The duplexer as in claim 19, wherein the first, second, and third resonators are film bulk acoustic resonators (FBARs).