Circuit and method for suppression of electromagnetic coupling and switching noise in multilayer printed circuit boards

• US 7,215,007 B2
• Filed: 03/03/2004
• Issued: 05/08/2007
• Est. Priority Date: 06/09/2003
• Status: Expired due to Fees

• Current Assignee: Wemtec Inc.
• Original Assignee: Wemtec Inc.
• Inventors: McKinzie, William E. III, Rogers, Shawn D.
• Primary Examiner(s): Tran; Thien F
• Application Number:
  US10/794,185
• Publication Number:
  US 20050029632A1
• Time in Patent Office: 1,161 Days
• Field of Search: 343/822, 343/829, 343/846, 343/909, 343/767, 343/700.MS, 333/12, 257/664, 257/259, 257/533, 257/665, 174/35.R, 307/101, 327/593
• US Class Current: 257/664
• CPC Class Codes: H01P 1/16 for mode selection, e.g. mode suppression or mode promotion; for mode conversion
• CPC Class Codes: H01P 1/2005 Electromagnetic photonic bandgaps [EPB], or photonic bandgaps [PBG]
• CPC Class Codes: H05K 1/162 incorporating printed capacitors
• CPC Class Codes: H05K 2201/093 Layout of power planes, ground planes or power supply conductors, e.g. having special clearance holes therein reduction of cross-talk, noise or interference by patterned shielding planes, ground planes or power planes H05K1/0224
• CPC Class Codes: H05K 2201/09309 Core having two or more power planes; Capacitive laminate of two power planes
• CPC Class Codes: H05K 2201/09663 Divided layout, i.e. conductors divided in two or more parts branched layout H05K2201/09254

Abstract

Apparatus for suppressing noise and electromagnetic coupling in the printed circuit board of an electronic device includes an upper conductive plate and an array of conductive coplanar patches positioned a distance t₂ from the upper conductive plate. The distance t₂ is chosen to optimize capacitance between the conductive coplanar patches and the upper conductive plate for suppression of noise or electromagnetic coupling. The apparatus further includes a lower conductive plate a distance t₁ from the array of conductive coplanar patches and conductive rods extending from respective patches to the lower conductive plate.

Claims

1. An apparatus for suppressing noise in an electrical device, the apparatus comprising:

an upper conductive plate;

an array of conductive coplanar patches a distance t₂ from the upper conductive plate, the distance t₂ chosen to optimize capacitance between the conductive coplanar patches and the upper conductive plate for suppression of noise;

a lower conductive plate a distance t₁ from the array of conductive coplanar patches; and

conductive rods extending from respective patches to the lower conductive plate.

2. The apparatus of claim 1 wherein the conductive rods comprise conducting vias in a printed circuit board structure.

3. The apparatus of claim 1 wherein the sum of distance t₁ and the distance t₂ is less than 1 mm.

4. The apparatus of claim 1 further comprising a lower dielectric layer having a relative dielectric constant ∈

_r1 and an upper dielectric layer having a relative dielectric constant ∈

_r2.

5. The apparatus of claim 4 wherein ∈

_r1 and ∈

_r2 are chosen such that ∈

_r2≧

∈

_r1.

6. The apparatus of claim 4 wherein the lower dielectric layer and the upper dielectric layer are configured such that the dielectric layer having the highest relative dielectric constant is the thinnest dielectric layer.

7. The apparatus of claim 4 wherein the lower dielectric layer has thickness substantially equal to t₁ and the upper dielectric layer has thickness substantially equal to t₂, the thicknesses being chosen so that t₂<

<

t₁.

8. The apparatus of claim 4 wherein the thickness t₂ is of the upper dielectric layer between the patches and the upper conductive plate and is no more than 50% of the height of the apparatus.

9. The apparatus of claim 1 wherein the apparatus is fabricated using low temperature co-fired ceramic technology.

10. The apparatus of claim 1 wherein the apparatus is fabricated on a semiconductor wafer.

11. The apparatus of claim 1 wherein each patch of the array of conductive coplanar patches has a shape selected from the group consisting of circular, square, triangular, rectangular and hexagonal.

12. The apparatus of claim 1 further comprising:

a second array of conductive planar patches positioned a distance from the lower conductive plate; and

second conductive rods extending from respective patches of the second array to the upper conductive plate.

13. The apparatus of claim 1 wherein the patches are uniform in size.

14. The apparatus of claim 1 wherein the patches are non-uniform in size.

15. The apparatus of claim 1 wherein a dispersion diagram for a unit cell of the apparatus is characterized by more than one transmission zero.

16. The apparatus of claim 1 wherein at least one transmission zero is adjustable to effectively merge fundamental and secondary stopbands.

17. The apparatus of claim 1 wherein the patches are non-uniform in type.

18. The apparatus of claim 17 wherein the non-uniform patches include at least some hexagonal patches and at least some triangular patches.

19. The apparatus of claim 1 wherein the conductive rods are non-uniform in diameter.

20. The apparatus of claim 1 wherein inductive traces are arranged in series between the conductive rods and the coplanar patches.

21. The apparatus of claim 1 wherein the patches have one of a first size and a second size.

22. The apparatus of claim 1 wherein the patches are spaced a uniform gap distance from surrounding patches.

23. The apparatus of claim 1 wherein at least one of the patches and the lower conductive plate are connected by multiple conductive rods.

24. The apparatus of claim 23 wherein the multiple conductive rods connecting one or more of the patches with the lower conductive plate are arranged in a circle.

25. The apparatus of claim 23 wherein the multiple conductive rods connecting one or more of the patches with the lower conductive plate are arranged in an array.

26. The apparatus of claim 23 wherein the multiple conductive rods connecting one or more of the patches with the lower conductive plate are randomly distributed.

27. The apparatus of claim 23 wherein adjacent patches are connected with the lower conductive plate by the same number and distribution of the multiple conductive rods.

28. The apparatus of claim 23 wherein adjacent patches are connected with the lower conductive plate by at least one of a different number or a different distribution of the conductive rods.

29. The apparatus of claim 28 wherein the patches are arranged such that at least one of the number of conductive rods and distribution of the conductive rods in patches adjacent to each other in orthogonal directions are different and patches adjacent to each other in directions between the orthogonal directions are the same.

30. A parallel plate waveguide comprising:

an upper conductive plate;

a lower conductive plate separated by a distance substantially less than 1 mm from the upper plate;

an array of conductive patches positioned on a plane which is spaced a first distance from the lower conductive plate by a first dielectric layer and spaced a second distance from the upper conductive plate by a second dielectric layer to create one or more stopbands of frequencies over which transverse electromagnetic (TEM) modes are suppressed when energy is applied to the parallel plate waveguide.

31. The parallel plate waveguide of claim 30 wherein the one or more stopbands include a fundamental stopband as the lowest frequency stopband.

32. The parallel plate waveguide of claim 30 wherein the fundamental stopband is defined by an upper frequency and a lower frequency and wherein a ratio of the upper frequency to the lower frequency exceeds 4:

1.

33. A parallel plate waveguide (PPW) configured to suppress noise at one or more stopbands of frequencies, the PPW comprising:

first and second substantially parallel conductive plates;

an plural of rods contained in a first dielectric layer and positioned substantially normal to the plates, the rods having a length which spans at least 80% of the height between the plates, one end of each rod terminating at a first plate and another end of the each rod terminating on a conductive patch positioned substantially parallel to the plates, the length of the rods chosen to define the one or more stopbands at frequencies of interest.

34. The PPW of claim 33 further comprising a second dielectric layer between the patch and a second plate.

35. The PPW of claim 34 wherein the relative dielectric constant of the second dielectric layer is much greater than the relative dielectric constant of the first dielectric layer.

36. The PPW of claim 34 wherein the thickness of the first dielectric layer is much greater than the thickness of the second dielectric layer.

37. The PPW of claim 33 wherein in the patch is one patch of an array of patches, each patch having a shape which is one of circular and polygonal.

38. The PPW of claim 33 wherein at least one of the patches is connected to the first plate by multiple conductive rods.

39. The PPW of claim 38 wherein the multiple conductive rods connecting one or more of the patches with the first plate are arranged in a circle or an array.

40. The PPW of claim 38 wherein the multiple conductive rods connecting one or more of the patches with the first plate are randomly distributed.

41. The PPW of claim 38 wherein adjacent patches are connected with the first plate by the same number and distribution of the multiple conductive rods.

42. The PPW of claim 38 wherein adjacent patches are connected with the first plate by at least one of a different number or a different distribution of the conductive rods.

43. The PPW of claim 42 wherein the patches are arranged such that at least one of the number of conductive rods and distribution of the conductive rods connected to patches adjacent to each other in orthogonal directions are different and patches adjacent to each other in directions between the orthogonal directions are the same.

44. Apparatus for suppressing noise in an electrical device, the apparatus comprising:

an upper conductive plate;

an array of conductive coplanar patches;

a lower conductive plate separated from the array of conductive coplanar patches by a dielectric layer; and

conductive rods connecting patches to the lower conductive plate, at least one of the patches connected to the lower conductive plate by multiple conductive rods.

45. The apparatus of claim 44 wherein the conductive rods comprise plated through vias in a printed circuit board structure.

46. The apparatus of claim 44 wherein each patch of the array of conductive coplanar patches has a shape selected from the group consisting of circular, square, triangular, rectangular and hexagonal.

47. The apparatus of claim 44 further comprising a second array of conductive planar patches separated from the lower conductive plate and from the first array of conductive planar patches.

48. The apparatus of claim 47 further comprising:

an upper conductive plate separated from the lower conductive plate and from the first array of conductive planar patches; and

second conductive rods extending from patches of the second array to the upper conductive plate.

49. The apparatus of claim 44 wherein the patches are uniform in size.

50. The apparatus of claim 44 wherein the patches are non-uniform in size.

51. The apparatus of claim 44 wherein the patches are non-uniform in type.

52. The apparatus of claim 44 wherein the conductive rods are non-uniform in diameter.

53. The apparatus of claim 44 wherein inductive traces are arranged in series between the conductive rods and the coplanar patches.

54. The apparatus of claim 44 wherein the patches are spaced a uniform gap distance from surrounding patches.

55. The apparatus of claim 44 wherein each of the patches and the lower conductive plate are connected by multiple conductive rods.

56. The apparatus of claim 44 wherein the multiple conductive rods connecting one or more of the patches with the lower conductive plate are arranged in one of a circle or an array.

57. The apparatus of claim 44 wherein the multiple conductive rods connecting one or more of the patches with the lower conductive plate are randomly distributed.

58. The apparatus of claim 44 wherein adjacent patches are connected with the lower conductive plate by the same number and distribution of the multiple conductive rods.

59. The apparatus of claim 44 wherein adjacent patches are connected with the lower conductive plate by at least one of a different number or a different distribution of the conductive rods.

60. The apparatus of claim 59 wherein the patches are arranged such that at least one of the number of conductive rods or distribution of the conductive rods in patches adjacent to each other in orthogonal directions are different and patches adjacent to each other in directions between the orthogonal directions are the same.