Component functioning with bulk acoustic waves having coupled resonators

• US 20050012570A1
• Filed: 04/30/2004
• Published: 01/20/2005
• Est. Priority Date: 04/30/2003
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Epcos AG (TDK Corporation)
• Inventors: Ruile, Werner, Korden, Christian
• Granted Patent: US 7,057,478 B2
• Time in Patent Office: Days
• US Class Current: 333/189
• CPC Class Codes: H03H 9/0095 using bulk acoustic wave devices
• CPC Class Codes: H03H 9/564 implemented with thin-film techniques
• CPC Class Codes: H03H 9/583 comprising a plurality of piezoelectric layers acoustically coupled
• CPC Class Codes: H03H 9/589 Acoustic mirrors
• CPC Class Codes: H03H 9/605 consisting of a ladder configuration

Abstract

A component that functions with bulk acoustic waves, particularly a bandpass filter, has an increased number of degrees of design freedom in order to improve the transmission characteristics of the component. The component has BAW resonators coupled acoustically in the vertical and/or lateral direction through common electrodes, coupling layer systems and through the excitation of lateral acoustic modes. Through the acoustic coupling of the resonators, it is possible to create additional pole points in the transfer function so that in this manner, the rejection band characteristics of a bandpass filter can be improved. Through acoustic paths which are added in addition to the electrical connection, the insertion loss can be reduced. Through an acoustic coupling instead of an electrical connection, decoupling between input and output loops of a circuit can be achieved.

Claims

1. A component that functions with bulk acoustic waves, said component comprising a multi-layer structure containing a resonator layer region which includes a first electrode layer arranged above and a second electrode layer arranged below and a piezoelectric layer arranged therebetween, all of the electrode layers being structured in the lateral plane so that they have at least two electrically isolated sub-electrodes for each electrode layer, in each case, two sub-electrodes being arranged over one another forming together with the piezoelectric layer lying therebetween a sub-resonator, at least two of the sub-resonators laterally arranged adjacent to one another in the resonator layer region being coupled acoustically through lateral acoustic mode.

2. A component according to claim 1, wherein the multi-layer structure has more than one resonator layer region, the resonator layer regions being arranged one over the other.

3. A component according to claim 2, which includes a coupling layer system being arranged between sub-electrodes facing one another of the sub-resonators.

4. A component according to claim 2, wherein the sub-resonators arranged directly over one another have a common middle sub-electrode.

5. A component according to claim 1, wherein the multi-layer structure is arranged on a carrier substrate.

6. A component according to claim 5, which includes an acoustic mirror being arranged between the carrier substrate and the multi-layer structure.

7. A component according to claim 1, wherein the sub-resonators which are acoustically coupled with one another are basic elements of a filter.

8. A component according to claim 7, in which additional basic elements are provided which are connected in series.

9. A component according to claim 1, in which the sub-electrodes are formed differently.

10. A component which functions with bulk acoustic waves and has a multi-layer structure, said component containing a resonator layer region which includes a piezoelectric layer having a first electrode layer arranged above the piezoelectric layer and a second electrode layer arranged below the piezoelectric layer, the electrode layers being structured in the lateral plane so that they provide at least four sub-electrodes in each electrode layer, two sub-electrodes arranged over one another forming together with the piezoelectric layer lying therebetween a sub-resonator, the sub-resonators formed in this manner forming with one another a bridge connection, at least two of the sub-resonators laterally arranged adjacent to one another being coupled acoustically through lateral acoustic mode.

11. A component according to claim 10, which has at least eight sub-resonators, the sub-resonators forming more than one bridge connection and the bridge connections being connected in series.

12. A component that functions as bulk acoustic waves with a multi-layer structure, said multi-layer structure containing at least two piezoelectric layers, an upper electrode layer, a middle electrode layer and a lower electrode layer, each of the electrode layers being structured in the lateral plane so that they provide at least two sub-electrodes, said sub-electrodes of the electrode layers forming together with the piezoelectric layer lying therebetween a sub-resonator with at least four sub-resonators resulting overall, the sub-resonators formed in this manner forming with one another a bridge connection.

13. A component that functions with bulk acoustic waves having a first signal path and a second signal path which are arranged, in each case, between two electrical gates, a first resonator being arranged selectively in the first signal path and/or parallel to the first signal path, a second resonator being arranged in the second signal path or parallel to the second signal path, the first and second resonators being acoustically coupled.

14. A component according to claim 13, wherein the first and second signal paths implement a transmission path and a corresponding reception path, the transmission and reception paths being formed to transmit a transmission signal and receive a reception signal of the same mobile radio system.

15. A component according to claim 13, wherein the first and second resonators are arranged in one of the following arrangements comprising the arrangement with the first resonator being arranged parallel to the first signal path and the second resonator being arranged in the second path and an arrangement with the first resonator being arranged in the first signal path and the second resonator being arranged parallel to the second signal path.

16. A component according to claim 13, wherein the first and second resonators are arranged in one of the following arrangements including an arrangement with the first resonator being parallel to the first signal path and the second resonator being parallel to the second path and an arrangement with the first resonator being arranged in the first signal path and the second resonator being arranged in the second signal path.

17. A component according to claim 13, wherein the first and second resonators are arranged in a resonator stack one over the other with a coupling layer being arranged therebetween.

18. A component according to claim 13, wherein the first and second resonators are arranged adjacent to one another and are coupled through a lateral acoustic mode.

19. A component that functions with bulk acoustic waves, said component having a multi-layer structure containing an upper piezoelectric layer, a lower piezoelectric layer and at least one middle piezoelectric layer arranged therebetween, a continuous upper electrode layer arranged above the upper piezoelectric layer, a continuous lower electrode layer arranged below the lower piezoelectric layer, a first middle electrode layer arranged above the lower piezoelectric layer, additional middle electrode layers being arranged between the piezoelectric layers, at least two of the middle electrode layers being structured in the lateral plane to form structured electrode layers which have at least two isolated sub-electrodes, a coupling layer system being arranged between the first middle electrode layer and the next middle electrode layer disposed thereabove, the sub-electrodes coacting with each other and with the other middle layers and the piezoelectric layers lying therebetween to form sub-resonators, said sub-resonators being arranged adjacent to one another and containing one of the middle piezoelectric layers being provided to couple in and couple out an electrical signal, the sub-resonators containing the topmost electrode layer forming, in each case, a coupling sub-resonator, the coupling sub-resonator being connected, in each case, acoustically to the sub-resonators lying thereunder.

20. A component according to claim 19, wherein the first middle electrode layer arranged over the lower piezoelectric layer is a continuous middle electrode layer.

21. A component according to claim 19, wherein the first middle electrode layer arranged directly over the lower piezoelectric layer is structured in the lateral plane to form at least two electrically isolated sub-electrodes.

22. A component that functions with bulk acoustic waves with a resonator stack, said component containing at least three piezoelectric layers and electrode layers arranged therebetween, said component having a signal path being arranged between the first and second electrode gates in which series resonators are interconnected with one another, the resonator stack having series resonators arranged outside in the stack and at least one series resonator arranged inside the stack with middle electrodes, the series resonators arranged outside and inside being connected in the signal path arranged over one another and acoustically coupled with one another, at least two of the middle electrodes being interconnected in each case with a parallel resonator connected in parallel to the signal path, at least one such connection being made by means of a bond wire, the parallel resonators and the lowermost of the series resonators arranged outside containing the same piezoelectric layer.

23. A component that functions with bulk acoustic waves with a signal path arranged between first and second electrode gates, said component having a plurality of resonators being formed by two electrodes and a piezoelectric layer arranged therebetween, said resonator being sub-divided into series resonators and parallel resonators, with the series resonators being arranged in the signal path and the parallel resonators being arranged parallel to the signal path, at least two of the resonators being acoustically coupled to form coupled resonators, said coupled resonators being selected from a group consisting of series resonators and parallel resonators.

24. A component according to claim 23, wherein the parallel resonators are connected in series.

25. A component that functions with bulk acoustic waves with a resonator stack, said component having a signal path which is arranged between a first electrical gate and a second electrical gate in which a series resonator is arranged, the resonator stack having the series resonator and a parallel resonator which are arranged over one another and are acoustically coupled with one another and which form a coupling pair, the parallel resonator being connected in parallel to the signal path.

26. A component according to claim 25, in which the electrode layer arranged below in the resonator stack is connected to a reference potential.

27. A component according to claim 25, in which the series resonator and the parallel resonator are coupled by a coupling layer system which is arranged therebetween and is acoustically at least partially transmissive.

28. A component according to claim 25, in which the series resonator and the parallel resonator of the coupling pair of electrically connected to one another.

29. A component according to claim 25, which includes an electrically interconnected coupling pair being provided which are arranged in the lateral direction adjacent to one another.