Implantable medical device incorporating integrated circuit notch filters

• US 6,539,253 B2
• Filed: 12/05/2000
• Issued: 03/25/2003
• Est. Priority Date: 08/26/2000
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Haubrich, Gregory J., Goedeke, Steven D., Thompson, David L.
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US09/729,845
• Publication Number:
  US 20020026224A1
• Time in Patent Office: 840 Days
• Field of Search: 607/2, 607/9, 607/60, 607/5
• US Class Current: 607/2
• CPC Class Codes: A61N 1/025 Digital circuitry features of electrotherapy devices, e.g. memory, clocks, processors
• CPC Class Codes: A61N 1/08 Arrangements or circuits for monitoring, protecting, controlling or indicating for external stimulators A61N1/3603; for implantable neurostimulators A61N1/36128; for heart stimulators A61N1/37; for defibrillators A61N1/3925
• CPC Class Codes: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: A61N 1/37211 Means for communicating with stimulators
• CPC Class Codes: A61N 1/37229 Shape or location of the implanted or external antenna

Abstract

Implantable medical devices (IMDs) having sense amplifiers for sensing physiologic signals and parameters, RF telemetry capabilities for uplink transmitting patient data and downlink receiving programming and interrogation commands to and from an external programmer or other medical device are disclosed. At least one IC chip and discrete components have a volume and dimensions that are optimally minimized to reduce its volumetric form factor. Miniaturization techniques include forming notch filters of MEMS structures or forming discrete circuit notch filters by one or more of: (1) IC fabricating inductors into one or more IC chips mounted to the RF module substrate; (2) mounting each IC chip into a well of the RF module substrate and using short bonding wires to electrically connect bond pads of the RF module substrate and the IC chip; and (3) surface mounting discrete capacitors over IC chips to reduce space taken up on the RF module substrate. The IC fabricated inductors are preferably fabricated as planar spiral wound conductive traces formed of high conductive metals to reduce trace height and width while maintaining low resistance, thereby reducing parasitic capacitances between adjacent trace side walls and with a ground plane of the IC chip. The spiral winding preferably is square or rectangular, but having truncated turns to eliminate 90° angles that cause point-to-point parasitic capacitances. The planar spiral wound conductive traces are further preferably suspended over the ground plane of the IC chip substrate by micromachining underlying substrate material away to thereby reduce parasitic capacitances.

Claims

1. An implantable medical device operable to perform a therapeutic and/or monitoring function in a living body while exposed to sources of electromagnetic interference (EMI) comprising:

a housing having a housing side wall and inner and outer wall surfaces of a predetermined contour enclosing a hermetically sealed chamber;

a battery enclosed within said hermetically sealed chamber; and

electronic circuitry enclosed within said hermetically sealed chamber powered by the battery comprising a plurality of discrete components and at least one integrated circuit IC chip having an IC chip substrate and mounted to a circuit board dimensioned to fit within said hermetically sealed chamber along with said battery, said electronic circuitry comprising at least one notch filter having an input and output that blocks predetermined EMI signal frequencies while passing other signal frequencies from the input to the output, the notch filter formed of at least one IC fabricated inductor formed integrally with said IC chip.

2. The implantable medical device of claim 1, wherein the IC fabricated inductor comprises a planar spiral formed of a continuous, conductive, spiral trace extending between bonding pads that is deposited as a layer of the IC chip substrate, the spiral trace having turning points that are angled at less than 90°

to reduce parasitic capacitance between adjacent turning points of the spiral trace.

3. The implantable medical device of claim 2, wherein the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate.

4. The implantable medical device of claim 3, wherein the IC chip substrate further comprises a ground plane spaced from said planar spiral, and said continuous conductive trace extending between the bonding pads is deposited over an exposed surface of a suspended platform of the IC chip substrate formed by micromachining substrate material between the exposed surface of the suspended platform and the ground plane away, to thereby reduce parasitic capacitances between adjacent turns of the trace through the IC chip substrate to the ground plane.

5. The implantable medical device of claim 1, wherein the IC fabricated inductor comprises a planar spiral formed of a continuous, conductive, spiral trace extending between bonding pads that is deposited as a layer of the IC chip substrate, the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate to the ground plane.

6. The implantable medical device of claim 5, wherein the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate.

7. The implantable medical device of claim 1, wherein the IC fabricated inductor is formed of a planar spiral formed of a continuous conductive trace extending between bonding pads that is deposited as a layer of the RF IC chip substrate, the IC chip substrate further comprises a ground plane spaced from said planar spiral, and said continuous conductive trace extending between the bonding pads is deposited over an exposed surface of a suspended platform of the IC chip substrate formed by micromachining substrate material between the exposed surface of the suspended platform and the ground plane away, to thereby reduce parasitic capacitances between adjacent turns of the trace through the IC chip substrate to the ground plane.

8. The implantable medical device of claim 7, wherein the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate.

9. The implantable medical device of claim 1, wherein the IC chip substrate further comprises a ground plane, and the IC fabricated inductor is formed of a planar spiral formed of a continuous conductive trace extending between bonding pads that is suspended above and spaced from said ground plane formed by micromachining substrate material between the exposed surface of the suspended planar spiral and the ground plane away, to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate to the ground plane.

10. The implantable medical device of claim 9, wherein the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate.

11. The implantable medical device of claim 1, wherein:

said electronic circuitry comprises an RF module incorporating a telemetry transceiver comprising an RF module substrate, an IC chip mounted to said RF module substrate and said least one IC fabricated inductor is formed integrally with said IC chip mounted to said RF module thereby reducing the volumetric form factor of the RF module.

12. The implantable medical device of claim 11, wherein:

said RF module substrate has a predetermined RF module substrate thickness, a well formed in said RF module substrate extending from an RF module substrate surface through at least a portion of said RF module substrate thickness, and at least one module bonding pad formed on the RF module substrate surface;

said IC chip has predetermined IC chip substrate thickness, is mounted within said well of said RF module substrate thereby reducing the form factor of the RF module, and has at least one IC bonding pad formed on an exposed IC chip surface; and

a conductor extending between said module bonding pad and said IC bonding pad.

13. The implantable medical device of any of the claims 1-12, wherein said notch filter further comprises at least one discrete capacitor mounted to the exposed surface of said IC chip.

14. An implantable medical device operable to perform a therapeutic and/or monitoring function in a living body while exposed to sources of electromagnetic interference (EMI) comprising:

a housing having a housing side wall and inner and outer wall surfaces of a predetermined contour enclosing a hermetically sealed chamber;

a battery enclosed within said hermetically sealed chamber;

at least one sense electrode located outside said housing adapted to be located in relation to body tissue to detect electrical signals of the body tissue;

sense amplifier circuitry enclosed within said hermetically sealed chamber powered by the battery and coupled to said sense electrode, the sense amplifier circuitry comprising a plurality of discrete components and at least one integrated circuit IC chip having an IC chip substrate and mounted to a circuit board dimensioned to fit within said hermetically sealed chamber along with said battery, said sense amplifier circuitry comprising at least one notch filter that blocks EMI signal frequencies received from the sense electrode and passes signal frequencies of interest, the notch filter formed of at least one IC fabricated inductor formed integrally with said IC chip.

15. The implantable medical device of claim 14, wherein the IC fabricated inductor comprises a planar spiral formed of a continuous, conductive, spiral trace extending between bonding pads that is deposited as a layer of the IC chip substrate, the spiral trace having turning points that are angled at less than 90°

to reduce parasitic capacitance between adjacent turning points of the spiral trace.

16. The implantable medical device of claim 15, wherein the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate.

17. The implantable medical device of claim 16, wherein the IC chip substrate further comprises a ground plane spaced from said planar spiral, and said continuous conductive trace extending between the bonding pads is deposited over an exposed surface of a suspended platform of the IC chip substrate formed by micromachining substrate material between the exposed surface of the suspended platform and the ground plane away, to thereby reduce parasitic capacitances between adjacent turns of the trace through the IC chip substrate to the ground plane.

18. The implantable medical device of claim 14, wherein the IC fabricated inductor comprises a planar spiral formed of a continuous, conductive, spiral trace extending between bonding pads that is deposited as a layer of the IC chip substrate, the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate to the ground plane.

19. The implantable medical device of claim 18, wherein the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate.

20. The implantable medical device of claim 14, wherein the IC fabricated inductor is formed of a planar spiral formed of a continuous conductive trace extending between bonding pads that is deposited as a layer of the RF IC chip substrate, the IC chip substrate further comprises a ground plane spaced from said planar spiral, and said continuous conductive trace extending between the bonding pads is deposited over an exposed surface of a suspended plafform of the IC chip substrate formed by micromachining substrate material between the exposed surface of the suspended platform and the ground plane away, to thereby reduce parasitic capacitances between adjacent turns of the trace through the IC chip substrate to the ground plane.

21. The implantable medical device of claim 20, wherein the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate.

22. The implantable medical device of claim 14, wherein the IC chip substrate further comprises a ground plane, and the IC fabricated inductor is formed of a planar spiral formed of a continuous conductive trace extending between bonding pads that is suspended above and spaced from said ground plane formed by micromachining substrate material between the exposed surface of the suspended planar spiral and the ground plane away, to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate to the ground plane.

23. The implantable medical device of claim 22, wherein the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate.

24. An implantable medical device operable to perform a therapeutic and/or monitoring function in a living body while exposed to sources of electromagnetic interference (EMI) comprising:

a housing having a housing side wall and inner and outer wall surfaces of a predetermined contour enclosing a hermetically sealed chamber;

a battery enclosed within said hermetically sealed chamber;

at least physiologic sensor located outside said housing adapted to be located in relation to body tissue to detect a physiologic body parameter;

physiologic signal processing circuitry enclosed within said hermetically sealed chamber powered by the battery and coupled to said physiologic sensor, the physiologic signal processing circuitry comprising a plurality of discrete components and at least one integrated circuit IC chip having an IC chip substrate and mounted to a circuit board dimensioned to fit within said hermetically sealed chamber along with said battery, said electronic circuitry comprising at least one notch filter that blocks predetermined EMI signal frequencies and passes other signal frequencies received from the physiologic sensor, the notch filter formed of at least one IC fabricated inductor formed integrally with said IC chip.

25. The implantable medical device of claim 24, wherein the IC fabricated inductor comprises a planar spiral formed of a continuous, conductive, spiral trace extending between bonding pads that is deposited as a layer of the IC chip substrate, the spiral trace having turning points that are angled at less than 90°

to reduce parasitic capacitance between adjacent turning points of the spiral trace.

26. The implantable medical device of claim 25, wherein the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate.

27. The implantable medical device of claim 26, wherein the IC chip substrate further comprises a ground plane spaced from said planar spiral, and said continuous conductive trace extending between the bonding pads is deposited over an exposed surface of a suspended platform of the IC chip substrate formed by micromachining substrate material between the exposed surface of the suspended platform and the ground plane away, to thereby reduce parasitic capacitances between adjacent turns of the trace through the IC chip substrate to the ground plane.

28. The implantable medical device of claim 24, wherein the IC fabricated inductor comprises a planar spiral formed of a continuous, conductive, spiral trace extending between bonding pads that is deposited as a layer of the IC chip substrate, the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate to the ground plane.

29. The implantable medical device of claim 28, wherein the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate.

30. The implantable medical device of claim 24, wherein the IC fabricated inductor is formed of a planar spiral formed of a continuous conductive trace extending between bonding pads that is deposited as a layer of the RF IC chip substrate, the IC chip substrate further comprises a ground plane spaced from said planar spiral, and said continuous conductive trace extending between the bonding pads is deposited over an exposed surface of a suspended platform of the IC chip substrate formed by micromachining substrate material between the exposed surface of the suspended platform and the ground plane away, to thereby reduce parasitic capacitances between adjacent turns of the trace through the IC chip substrate to the ground plane.

31. The implantable medical device of claim 30, wherein the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate.

32. The implantable medical device of claim 24, wherein the IC chip substrate further comprises a ground plane, and the IC fabricated inductor is formed of a planar spiral formed of a continuous conductive trace extending between bonding pads that is suspended above and spaced from said ground plane formed by micromachining substrate material between the exposed surface of the suspended planar spiral and the ground plane away, to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate to the ground plane.

33. The implantable medical device of claim 32, wherein the spiral trace and bonding pads consist of a high conductivity conductor selected from the group consisting of gold, copper and aluminum-copper metallization to reduce trace height and width to thereby reduce parasitic capacitances between adjacent turns of the trace and through the IC chip substrate.

34. An implantable medical device operable to perform a therapeutic and/or monitoring function in a living body while exposed to sources of electromagnetic interference (EMI) comprising:

a housing having a housing side wall and inner and outer wall surfaces of a predetermined contour enclosing a hermetically sealed chamber;

a battery enclosed within said hermetically sealed chamber;

electronic circuitry enclosed within said hermetically sealed chamber powered by the battery comprising a plurality of discrete components and at least one integrated circuit IC chip having an IC chip substrate and mounted to a circuit board dimensioned to fit within said hermetically sealed chamber along with said battery, said electronic circuitry comprising at least one notch filter having an input and output that blocks passage of predetermined EMI signal frequencies and passes other signal frequencies from the input to the output, the notch filter formed of at least one IC fabricated microelectromechanical filter element formed integrally with said IC chip.

35. The implantable medical device of claim 34, wherein the electronic circuitry further includes an amplifier coupled to the microelectromechanical filter and a demodulator coupled to the amplifier;

and wherein the microelectromechanical filter, the amplifier and the demodulator are fabricated on a common IC die.

36. The implantable medical device of claim 34, wherein:

said implantable medical device further comprises at least one sense electrode located outside said housing adapted to be located in relation to body tissue to conduct electrical signals of the body tissue having a predetermined frequency bandwidth to said electronic circuitry;

the electronic circuitry comprises a sense amplifier circuit for amplifying and processing the electrical signals of the body tissue; and

the microelectromechanical filter is coupled electrically between the sense electrode and a stage of the sense amplifier circuit and is tuned to pass the electrical signals of body tissue and to not pass EMI signal frequencies.

37. The implantable medical device of claim 34, wherein:

said implantable medical device further comprises a telemetry antenna and a telemetry transceiver coupled to the telemetry antenna enabling telemetry transmissions with other medical devices at a predetermined telemetry carrier frequency and data encoding bandwidth; and

the microelectromechanical filter is coupled electrically between the telemetry antenna and telemetry transceiver and tuned to pass the telemetry carrier frequency and data encoding frequencies and to not pass predetermined EMI signal frequencies.

38. The implantable medical device of claim 34, wherein:

said implantable medical device further comprises at least one physiologic sensor located outside said housing adapted to be located in relation to body tissue to measure a physiologic parameter of the body and provide a physiologic signal having a predetermined frequency bandwidth to said electronic circuitry;

the electronic circuitry comprises a physiologic signal processor circuit for amplifying and processing the physiologic signals of the body tissue having a predetermined frequency bandwidth; and

the microelectromechanical filter is coupled electrically between the physiologic sensor and a stage of the physiologic signal processor circuit sense amplifier circuit and tuned to pass the physiologic signals of body tissue and to block predetermined EMI signal frequencies.