FILTER WITH INTEGRATED LOADING CAPACITORS

• US 20100214037A1
• Filed: 02/23/2009
• Published: 08/26/2010
• Est. Priority Date: 02/23/2009
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Musiol, Lothar Johannes, Plager, Steve
• Granted Patent: US 8,547,188 B2
• Time in Patent Office: Days
• US Class Current: 333/185
• CPC Class Codes: H01P 1/20345 Multilayer filters
• CPC Class Codes: H03H 2001/0085 Multilayer, e.g. LTCC, HTCC, green sheets inside PCB filters H05K
• CPC Class Codes: H03H 7/0123 comprising distributed impedance elements together with lumped impedance elements
• CPC Class Codes: H03H 7/09 Filters comprising mutual inductance
• CPC Class Codes: H03H 7/1708 Comprising bridging elements, i.e. elements in a series path without own reference to ground and spanning branching nodes of another series path H03H7/07 takes precedence
• CPC Class Codes: H03H 7/1725 Element to ground being common to different shunt paths, i.e. Y-structure
• CPC Class Codes: H03H 7/1791 Combined LC in shunt or branch path

Abstract

There is provided an improved filter having resonators substantially disposed between conductive planes which form one or more loading capacitors that are in turn coupled to the resonators. Further, inclusion of a designed void or slot in one or more of the conductive planes allows for control of an introduced transmission zero to manipulate the performance of the filter to achieve desired results, such as improved skirt performance.

Claims

1. A filter disposed within a multilayer substrate, the filter comprising:

a first and second resonator, the first and second resonators respectively having a short circuit end and an open circuit end, the respective short circuit ends of the first and second resonators coupled to a first ground plane;

an input coupled to the first resonator;

an output coupled to the second resonator;

a first loading capacitor coupled to the open circuit end of the first resonator, the first loading capacitor comprising a first capacitor plate and a second capacitor plate;

a second loading capacitor coupled to the open circuit end of the second resonator, the second loading capacitor comprises a first capacitor plate and a second capacitor plate; and

wherein the first and second resonators are disposed in a resonator plane substantially parallel to and vertically displaced from at least one of the respective first capacitor plate and the second capacitor plate of the respective first and second loading capacitors, wherein at least one of the first and second resonators is at least partially overlapped by at least one of;

the first capacitor plate or the second capacitor plate of the first loading capacitor, or

the first capacitor plate or the second capacitor plate of the second loading capacitor.

2. The filter as disclosed in claim 1, wherein the second capacitor plate of the first loading capacitor and the second capacitor plate of the second loading capacitor are substantially coplanar and are coupled to the first ground plane.

3. The filter as disclosed in claim 1, wherein the first ground plane includes at least one void area wherein the void area forms a substantially isolated region of the first ground plane.

4. The filter as disclosed in claim 3, wherein the at least one void area comprises a slot of a predetermined width at least partially circumscribing a portion of the first ground plane proximal to the second capacitor plates of the first and second loading capacitors.

5. The filter as disclosed in claim 3, wherein the at least one void area comprises a plurality of slots of respective predetermined widths creating a respective plurality of at least partially isolated regions comprising the second capacitor plates of the first and second loading capacitors.

6. The filter as disclosed in claim 3, wherein the at least one void area comprises a slot of a predetermined width at least partially circumscribing a nearly complete rectangular area of the first ground plane.

7. The filter as disclosed in claim 6, wherein the nearly complete rectangular area is equal to or larger than the projected area of the first capacitor plate of the first loading capacitor and the first capacitor plate of the second loading capacitor.

8. The filter as disclosed in claim 3 further comprising an inductor coupled between at least one of the second capacitor plates of the first and second loading capacitors and the first ground plane.

9. The filter as disclosed in claim 8, wherein the value of the inductor is controlled by a predetermined dimension of a conductive coupling region disposed between at least two edges of the at least one void area of the first ground plane.

10. The filter as disclosed in claim 1 further comprising a third loading capacitor coupled to the first resonator, and a fourth loading capacitor coupled to the second resonator, the third and fourth loading capacitors respectively comprising a first capacitor plate and a second capacitor plate wherein at least one of the first capacitor plates of the third and fourth loading capacitors overlap at least one of the first and second resonators.

11. The filter as disclosed in claim 10, wherein the second capacitor plate of the third loading capacitor and the second capacitor plate of the fourth loading capacitor are substantially coplanar and are coupled to a second ground plane.

12. The filter as disclosed in claim 11, wherein the second ground plane includes at least one void area wherein the void area forms a substantially isolated region of the second ground plane.

13. The filter as disclosed in claim 12, wherein the at least one void area comprises a slot of a predetermined width at least partially circumscribing a portion of the second ground plane proximal to the second capacitor plates of the third and fourth loading capacitors.

14. The filter as disclosed in claim 12, wherein the at least one void area comprises a plurality of slots of predetermined widths creating a respective plurality of at least partially isolated regions comprising the second capacitor plates of the third and fourth loading capacitors.

15. The filter as disclosed in claim 12, wherein the at least one void area comprises a slot of a predetermined width at least partially circumscribing a nearly complete rectangular area of the second ground plane.

16. The filter as disclosed in claim 12 further comprising an inductor coupled between at least one of the second capacitor plates of the third and fourth loading capacitors and the second ground plane.

17. The filter as disclosed in claim 16, wherein the value of the inductor is controlled by a predetermined dimension of a conductive coupling region disposed between at least two edges of the at least one void area of the second ground plane.

18. The filter as disclosed in claim 1, wherein the first and second resonators comprise a substantially serpentine meander shape.

19. The filter as disclosed in claim 1, wherein the substrate comprises at least one of a low temperature co-fired ceramic substrate, a high temperature co-fired ceramic substrate, a silicon substrate, a gallium arsenide substrate, a thin film substrate, and an organic circuit substrate.

20. A filter disposed within a multilayer substrate, the filter comprising:

first and second resonators, the first and second resonators respectively having a short circuit end and an open circuit end, the respective short circuit ends of the first and second resonators coupled to a first ground plane;

an input coupled to the first resonator;

an output coupled to the second resonator;

at least one loading capacitor coupled to the open circuit end of at least one of the first and second resonators, wherein;

the at least one loading capacitor includes a two or more parallel conductive elements including one or more conducting plates and one or more ground plates;

the one or more ground plates includes at least one void area in proximity to the conducting plate; and

the first and second resonators are substantially disposed in a resonator plane parallel to and vertically displaced from at least one of the conducting plate and the ground plate, wherein at least one of the conducting plate and the ground plate overlap at least one of the first and second resonators.

21. The filter as disclosed in claim 20, wherein the one or more ground plates are substantially coplanar and are coupled to the first ground plane.

22. The filter as disclosed in claim 20, wherein the void area forms a substantially isolated region of the first ground plane and further includes the one or more ground plates of the at least one loading capacitor.

23. The filter as disclosed in claim 20, wherein the at least one void area comprises a slot of a predetermined width at least partially circumscribing a portion of the first ground plane proximal to the one or more ground plates of the at least one loading capacitor.

24. The filter as disclosed in claim 20, wherein the at least one void area comprises a plurality of slots of a predetermined widths creating a respective plurality of at least partially isolated regions comprising the one or more ground plates of the at least one loading capacitors.

25. The filter as disclosed in claim 20, wherein the at least one void area comprises a slot of a predetermined width at least partially circumscribing a nearly complete rectangular area of the first ground plane.

26. The filter as disclosed in claim 25, wherein the nearly complete rectangular area is equal to or larger than the projected area of the one or more conducting plates of the at least one loading capacitor.

27. The filter as disclosed in claim 20 further comprising an inductor coupled between the one or more ground plates of the at least one loading capacitor and the first ground plane.

28. The filter as disclosed in claim 27, wherein the value of the inductor is controlled by a predetermined dimension of a conductive coupling region disposed between at least two edges of the at least one void area of the first ground plane.

29. The filter as disclosed in claim 20, wherein the first and second resonators comprise a substantially serpentine meander shape.

30. The filter as disclosed in claim 20, wherein the substrate comprises at least one of a low temperature co-fired ceramic substrate, a high temperature co-fired ceramic substrate, a silicon substrate, a gallium arsenide substrate, a thin film substrate, and an organic circuit substrate.

31. A differential filter disposed within a multilayer substrate, the filter comprising:

first and second resonators, the first and second resonators coplanar and respectively having a short circuit end and an open circuit end, the respective short circuit ends of the first and second resonators coupled to a first ground plane;

a first input coupled to the first resonator;

a first output coupled to the second resonator;

third and fourth resonators, the third and fourth resonators coplanar and respectively having a short circuit end and an open circuit end, the respective short circuit ends of the third and fourth resonators coupled to the first ground plane wherein the first and second resonators are respectively disposed in vertically offset substantially parallel proximity to the third and fourth resonators;

a second input coupled to the third resonator;

a second output coupled to the fourth resonator; and

four loading capacitors respectively coupled to the open circuit ends of the four resonators, wherein;

the loading capacitors respectively comprise two or more parallel conductive elements including one or more conducting plates and a one or more ground plates, wherein at least one of the conducting plates and the ground plates overlap at least one of the first, second, third, and fourth resonators.

32. The filter as disclosed in claim 31, wherein the one or more ground plates are substantially coplanar and are coupled to the first ground plane.

33. The filter as disclosed in claim 31, wherein the void area forms a substantially isolated region of the first ground plane and further includes the one or more ground plates of the four loading capacitors.

34. The filter as disclosed in claim 31, wherein the at least one void area comprises a slot of a predetermined width at least partially circumscribing a portion of the first ground plane proximal to the ground plates of the four loading capacitors.

35. The filter as disclosed in claim 31, wherein the at least one void area comprises a plurality of slots of a predetermined widths creating a respective plurality of at least partially isolated regions comprising the one or more ground plates of the at least one loading capacitors.

36. The filter as disclosed in claim 31, wherein the at least one void area comprises a slot of a predetermined width at least partially circumscribing a nearly complete rectangular area of the first ground plane.

37. The filter as disclosed in claim 36, wherein the nearly complete rectangular area is equal to or larger than the projected area of the one or more conducting plates of the four loading capacitors.

38. The filter as disclosed in claim 31 further comprising an inductor coupled between the one or more ground plates of the four loading capacitors and the first ground plane.

39. The filter as disclosed in claim 38, wherein the value of the inductor is controlled by a predetermined dimension of a conductive coupling region disposed between at least two edges of the at least one void area of the first ground plane.

40. The filter as disclosed in claim 31, wherein the first, second, third, and fourth resonators comprise a substantially serpentine meander shape.

41. The filter as disclosed in claim 31, wherein the substrate comprises at least one of a low temperature co-fired ceramic substrate, a high temperature co-fired ceramic substrate, a silicon substrate, a gallium arsenide substrate, a thin film substrate, and an organic circuit substrate.