RF Filter Device

• US 20090179716A1
• Filed: 01/09/2009
• Published: 07/16/2009
• Est. Priority Date: 01/09/2008
• Status: Abandoned Application

• Current Assignee: Anaren Incorporated (TTM Technologies Incorporated)
• Original Assignee: Anaren Incorporated (TTM Technologies Incorporated)
• Inventors: Gay, Simon D.
• Application Number:
  US12/351,573
• Publication Number:
  US 20090179716A1
• Time in Patent Office: Days
• US Class Current: 333/204
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/086 Magnetic resonance imaging [MRI] compatible leads
• CPC Class Codes: H01F 17/0013 with stacked layers
• CPC Class Codes: H03H 1/0007 of radio frequency interference filters
• CPC Class Codes: H03H 2001/0085 Multilayer, e.g. LTCC, HTCC, green sheets inside PCB filters H05K
• CPC Class Codes: H03H 7/1766 Parallel LC in series path H03H7/1783 takes precedence
• CPC Class Codes: H03H 7/1783 Combined LC in series path
• CPC Class Codes: Y10T 29/49016 Antenna or wave energy "plumbing" making

Abstract

The present invention is directed to an integrated filter device for an implantable element. The device includes at least one filter component having N-circuit layers, N being an integer greater than or equal to one. Each of the N-circuit layers includes a first dielectric material having a first conductive material disposed thereon, the first dielectric material being characterized by a relatively low dielectric constant. The first conductive material is characterized by a relatively high electrical conductivity and arranged in a predetermined pattern on a surface of the first dielectric material of each of the N-circuit layers. The first conductive material on each of the N-circuit layers is coupled to the first conductive material disposed on an adjacent layer of the N-circuit layers such that the N-circuit layers form an inductor disposed in parallel with a first capacitance. At least one tuning element is coupled to the at least one filter component and configured to tune the at least one filter component to resonate at a predetermined selected resonance frequency. The at least one tuning element includes a second dielectric material characterized by a relatively high dielectric constant. A dimension of the at least one tuning element and the predetermined selected resonance frequency are a function of a ratio of the high dielectric constant over the low dielectric constant.

Claims

1. An integrated filter device for an implantable element, the device comprising:

at least one filter component including N-circuit layers, N being an integer greater than or equal to one, each of the N-circuit layers including a first dielectric material having a first conductive material disposed thereon, the first dielectric material being characterized by a relatively low dielectric constant, the first conductive material being characterized by a relatively high electrical conductivity and arranged in a predetermined pattern on a surface of the first dielectric material of each of the N-circuit layers, the first conductive material on each of the N-circuit layers being coupled to the first conductive material disposed on an adjacent layer of the N-circuit layers such that the N-circuit layers form an inductor disposed in parallel with a first capacitance; and

at least one tuning element coupled to the at least one filter component and configured to tune the at least one filter component to resonate at a predetermined selected resonance frequency, the at least one tuning element including a second dielectric material characterized by a relatively high dielectric constant, a dimension of the at least one tuning element and the predetermined selected resonance frequency being a function of a ratio of the high dielectric constant over the low dielectric constant.

2. The device of claim 1, wherein the at least one filter component includes a plurality of filter components such that the filter device is configured to resonate at a plurality of predetermined selected resonance frequencies.

3. The device of claim 2, wherein each of the plurality of filter components are arranged at a predetermined angular orientation relative to an adjacent filter component to generate a predetermined degree of inductive coupling between adjacent filter components to effect predetermined bandwidth characteristics of the plurality of predetermined selected resonance frequencies.

4. The device of claim 2, wherein each of the plurality of filter components are arranged in a substantially orthogonal position relative to an adjacent filter component to substantial cancel inductive coupling between adjacent filter components.

5. The device of claim 1, wherein the first dielectric material of the N-circuit layers includes a ceramic material.

6. The device of claim 5, wherein the ceramic material is selected from a group of ceramic materials that include alumina, quartz or polymer materials.

7. The device of claim 1, wherein the relatively low dielectric constant of the first dielectric material is greater than one (1).

8. The device of claim 7, wherein the relatively low dielectric constant of the first dielectric material is within a range substantially between two and ten.

9. The device of claim 1, wherein each of the N-circuit layers including the first dielectric material is characterized by a thickness in a range between one (1.0) and two (2.0) mils.

10. The device of claim 1, wherein each layer of the N-circuit layers is characterized by a thermal conductivity in a range between 3.0 W/m-K and 200 W/m-K.

11. The device of claim 1, wherein the first conductive material is selected from a group of materials that includes silver (Ag), gold (Au), tungsten (W), a composite material or copper (Cu).

12. The device of claim 11, wherein the relatively high electrical conductivity of the first conductive material is a conductivity within a range including 4.0×

10⁷ S/M through 7.0×

10⁷ S/M.

13. The device of claim 1, wherein the predetermined pattern of the first conductive material is characterized by a meandered line segment.

14. The device of claim 1, wherein the first conductive material is characterized by a predetermined cross-sectional shape and predetermined cross-sectional area.

15. The device of claim 14, wherein the first conductive material is characterized by a D.C. resistance is less than or equal to 5 Ohms.

16. The device of claim 14, wherein the first conductive material is characterized by a minimum of substantially three (3) skin depths.

17. The device of claim 14, wherein the predetermined cross-sectional shape is substantially elliptical.

18. The device of claim 1, wherein an inductance of the inductor is within an approximate range between 500-800 nH and the at least one filter component is characterized by a quality factor (Q) greater than 20.

19. The device of claim 1, wherein a cross-sectional area of the at least one filter component is less than 2,000 mil².

20. The device of claim 1, wherein a cross-sectional area of the at least one filter component is less than 7,000 mil².

21. The device of claim 1, wherein N is within a range between 1 and 80.

22. The device of claim 1, wherein the relatively high dielectric constant of the second dielectric material is characterized by a dielectric constant within a range between 100 and 1,000 based on the predetermined selected resonance frequency.

23. The device of claim 1, wherein the at least one tuning element includes at least one second capacitor disposed in parallel with the first capacitance.

24. The device of claim 23, wherein the at least one second capacitance is configured as a parallel plate capacitor disposed on an exterior portion of the at least one filter component, the at least one second capacitor having a first conductive plate and a second conductive plate with the second dielectric material disposed therebetween.

25. The device of claim 23, wherein the at least one second capacitor includes at least one capacitor tuning feature configured to tune the at least one filter component to resonate at the predetermined selected resonance frequency.

26. The device of claim 25, wherein the at least one capacitor tuning feature includes one or more removable capacitor portions.

27. The device of claim 26, wherein the at least one capacitor tuning feature includes the disposition of a third dielectric material over the at least one second capacitor.

28. The device of claim 25, further comprising at least one connective conductor configured to couple the at least one second capacitor and the first conductive material such that the first conductive material is not accessible via the external portion, the at least one connective conductor being comprised of a relatively inert biocompatible material.

29. The device of claim 28, wherein the at least one connective conductor is selected from a group of substantially inert conductors including at least platinum (Pt), a composite material or palladium (Pd).

30. The device of claim 25, wherein the at least one connective conductor is connected to the first conductive material at a transition point.

31. The device of claim 30, wherein the transition point is disposed in a via filled with a material selected from a group of materials including PtAg, a composite material or PdAg.

32. The device of claim 1, wherein the relatively high dielectric constant of the second dielectric material is in a range substantially between 500-1,000.

33. The device of claim 1, wherein the ratio of the high dielectric constant over the low dielectric constant is in a range substantially between 250 and 500.

34. The device of claim 1, wherein the at least one tuning element is formed by interleaving M-layers of the second dielectric material between the N-layers of the first dielectric material, the ratio of the relatively high dielectric constant to the relatively low dielectric constant being selected to tune the at least one filter component to resonate at substantially the predetermined selected resonance frequency.

35. The device of claim 1, wherein the at least one tuning element comprises:

M-layers of the second dielectric material interleaved between the N-layers of the first dielectric material, the ratio of the relatively high dielectric constant to the relatively low dielectric constant being selected to tune the at least one filter component to resonate at a frequency that is within a range of frequencies that includes the predetermined selected resonance frequency;

at least one second capacitance disposed in parallel with the first capacitance and configured as a parallel plate capacitor disposed on an exterior portion of the at least one filter component, the at least one second capacitor having a first conductive plate and a second conductive plate with the second dielectric material or a third dielectric material disposed therebetween, the third dielectric material being characterized by a relatively high dielectric constant, the at least one second capacitance being configured to tune the at least one filter component to resonate at the predetermined selected resonance frequency.

36. A method for making a miniaturized integrated filter device for an implantable element, the method comprising:

a) providing N-layers of dielectric material, the dielectric material being characterized by a relatively low dielectric constant, N being an integer value greater than or equal to one;

b) disposing a first conductive material on each of the N-layers of dielectric material to form N-circuit layers, the first conductive material being characterized by a relatively high electrical conductivity and arranged in a predetermined pattern on a surface of the first dielectric material;

c) integrating the N-circuit layers to form an inductor disposed in parallel with a first capacitance; and

d) providing at least one tuning element either before the step of integrating or after the step of integrating to form a filter component, the at least one at least one tuning element including a second dielectric material characterized by a relatively high dielectric constant and configured to tune the filter component to resonate at a predetermined selected resonance frequency, a dimension of the at least one tuning element and the predetermined selected resonance frequency being a function of a ratio of the high dielectric constant over the low dielectric constant.

37. The method of claim 36, further comprising:

repeating steps a) through d) to form at least one second filter component characterized by at least one second predetermined resonance frequency; and

coupling the filter component to the at least one second filter component, the at least one second filter component being disposed in a substantially orthogonal arrangement to substantially minimize inductive coupling between the filter component and the at least one second filter component.

38. The method of claim 36, further comprising:

repeating steps a) through d) to form at least one second filter component characterized by at least one second predetermined resonance frequency to form a plurality of adjacent filter components; and

coupling at least one of the filter component and the least one second filter component to an adjacent filter component at a predetermined angular orientation to select a predetermined degree of coupling between the adjacent filter components to selectively control bandwidth characteristics within a frequency band including the plurality of predetermined selected resonance frequencies.

39. The method of claim 36, wherein the step of providing N-layers of dielectric material includes providing N-layers of ceramic green-tape material selected from a group of materials including alumina, quartz or polymer materials.

40. The method of claim 39, wherein the step of integrating the N-circuit layers further comprises:

laminating the N-layers of ceramic green-tape material; and

heating the N-layers of ceramic green-tape material in accordance with a predetermined firing profile, the predetermined firing profile specifying various temperature levels as a function of time.

41. The method of claim 40, wherein the predetermined selected resonance frequency is a function of the firing profile.

42. The method of claim 40, wherein each of the N-circuit layers is characterized by a thickness in a range between one (1.0) and two (2.0) mils.

43. The method of claim 40, wherein each layer of the N-circuit layers is characterized by a thermal conductivity in a range between 3.0 W/m-K and 200 W/m-K.

44. The method of claim 36, wherein the step of providing at least one tuning element further comprises interleaving M-layers of the second dielectric material between the N-layers of the first dielectric material, the ratio of the relatively high dielectric constant to the relatively low dielectric constant being selected to tune the at least one filter component to resonate at substantially the predetermined selected resonance frequency.

45. The method of claim 36, wherein the step of providing at least one tuning element further comprises:

disposing at least one second capacitance in parallel with the first capacitance;

coupling the at least one second capacitor to the first conductive material via a connective conductor such that the at least one second capacitor is disposed in parallel with the first capacitance, the at least one connective conductor being comprised of a relatively inert biocompatible conductive material such that the first conductive material is substantially inaccessible via the external portion.

46. The method of claim 45, further comprising the step of tuning the at least one second capacitor such that the band stop filter is characterized by the predetermined resonance frequency.

47. The method of claim 36, wherein the first conductive material is selected from a group of materials that includes silver (Ag), gold (Au), a composite material, copper (Cu), or a material having a conductivity within a range including 4.0×

10⁷ S/M through 7.0×

10⁷ S/M.

48. The method of claim 36, wherein the first conductive material is characterized by a D.C. resistance is less than or equal to 5 Ohms and is characterized by a minimum of three (3) skin depths.