LOW LOSS BAND PASS FILTER FOR RF DISTANCE TELEMETRY PIN ANTENNAS OF ACTIVE IMPLANTABLE MEDICAL DEVICES

• US 20080195180A1
• Filed: 08/16/2007
• Published: 08/14/2008
• Est. Priority Date: 06/08/2006
• Status: Active Grant

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Inventors: Dabney, Warren S., Stevenson, Robert A.
• Granted Patent: US 9,042,999 B2
• Time in Patent Office: Days
• US Class Current: 607/60
• 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: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents
• CPC Class Codes: H03H 1/0007 of radio frequency interference filters
• CPC Class Codes: H03H 7/175 Series LC in series path H03H7/1783 takes precedence
• CPC Class Codes: H03H 7/1775 Parallel LC in shunt or branch path H03H7/1791 takes precedence

Abstract

A hermetic terminal for an active implantable medical device (AIMD), includes an RF distance telemetry pin antenna, a capacitor conductively coupled between the antenna and a ground for the AIMD, and an inductor electrically disposed in parallel with the capacitor and conductively coupled between the antenna and a ground for the AIMD. The capacitor and the inductor form a band pass filter for attenuating electromagnetic signals through the antenna except at a selected frequency band. Values of capacitance and inductance are selected such that the band pass filter is resonant at the selected frequency band. In an alternative form, the band pass filter is coupled in series with the telemetry pin antenna for attenuating MRI signals of a selected frequency band.

Claims

1. An active medical device (AMD), comprising:

an RF distance telemetry pin; and

a band stop filter associated with the telemetry pin for attenuating current flow through the telemetry pin at a selected frequency, wherein the band stop filter comprises a capacitor in parallel with an inductor, said band stop filter being placed in series with the telemetry pin, wherein values of capacitance and inductance are selected such that the band stop filter is resonant at the selected frequency.

2. The active medical device of claim 1, wherein a Q factor for said inductor is relatively maximized and a Q factor for said capacitor is relatively minimized to reduce the overall Q of the band stop filter.

3. The active medical device of claim 2, wherein the Q factor for said inductor is relatively maximized by minimizing resistive loss in the inductor.

4. The active medical device of claim 2, wherein the Q factor for said capacitor is relatively minimized by raising equivalent series resistance of the capacitor.

5. The active medical device of claim 1, wherein said selected frequency comprises a selected frequency band.

6. The active medical device of claim 1, wherein said selected frequency includes pulsed MRI signals.

7. The active medical device of claim 1, wherein the AMD comprises a cochlear implant, a piezoelectric sound bridge transducer, a neurostimulator, a brain stimulator, a cardiac pacemaker, a ventricular assist device, an artificial heart, a drug pump, a bone growth stimulator, a bone fusion stimulator, a urinary incontinence device, a pain relief spinal cord stimulator, an anti-tremor stimulator, a gastric stimulator, an implantable cardioverter defibrillator, a congestive heart failure device, a neuromodulator, a cardiovascular stent, or an orthopedic implant.

8. The active medical device of claim 1, further comprising a device housing, and a hermetic terminal assembly for supporting said telemetry pin in a position projecting at least a short distance at an exterior of said device housing, said band stop filter being disposed generally at an inboard side of said hermetic terminal assembly.

9. The active medical device of claim 8, further including at least one lead wire extending from said device housing for contact with patient tissue.

10. The active medical device of claim 9, wherein said at least one lead wire projecting through said hermetic terminal assembly.

11. The active medical device of claim 9, further including a feedthrough capacitor associated with said at least one lead wire.

12. The active medical device of claim 1, wherein said band stop comprises a first tank circuit, and further including a second tank circuit having a capacitor in parallel with an inductor and coupled between said telemetry pin and a ground plane, said second tank circuit having values of capacitance and inductance selected for resonance at a different selected frequency.

13. A band stop filter for a telemetry pin on an active medical device (AMD), comprising:

a capacitor in parallel with an inductor, said parallel capacitor and inductor combination being placed in series with the telemetry pin, wherein values of capacitance and inductance are selected such that the band stop filter is resonant at a selected frequency.

14. The band stop filter of claim 13, wherein a Q factor for said inductor is relatively maximized and a Q factor for said capacitor is relatively minimized to reduce the overall Q of the band stop filter.

15. The band stop filter of claim 14, wherein the Q factor for said inductor is relatively maximized by minimizing resistive loss in the inductor.

16. The band stop filter of claim 14, wherein the Q factor for said capacitor is relatively minimized by raising equivalent series resistance of the capacitor.

17. The band stop filter of claim 13, wherein said selected frequency comprises a selected frequency band.

18. The band stop filter of claim 13, wherein said selected frequency includes pulsed MRI signals.

19. A process for attenuating current flow through a telemetry pin of an active medical device (AMD) at a selected frequency range, comprising the steps of:

selecting a capacitor having a Q factor that is relatively minimized so as to resonate substantially throughout said selected frequency range;

selecting an inductor having a Q factor which is relatively maximized so that the inductor will resonate substantially throughout said selected frequency range;

utilizing the selected capacitor and the selected inductor to form a band stop filter; and

placing the band stop filter in series with the telemetry pin, wherein the overall Q factor of the band stop filter is reduced to attenuate current flow through the telemetry pin substantially throughout said selected frequency range.

20. The process of claim 19 wherein the said selected frequency range includes a plurality of MRI pulsed frequencies.

21. The process of claim 19 including the step of raising the equivalent series resistance of said capacitor to relatively maximize the capacitor Q factor.

22. The process of claim 19 including the step of minimizing resistive loss in said inductor to relatively minimize the inductor Q factor.