Low loss band pass filter for RF distance telemetry pin antennas of active implantable medical devices

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

a) a housing for the AMD;

b) an electronic circuit board or substrate disposed on an inboard side opposite an outboard body fluid side of the housing;

c) a hermetic feedthrough terminal, comprising:

i) a ferrule comprising a ferrule sidewall having an outer surface spaced from an inner surface, wherein the outer ferrule surface is hermetically sealed to an opening in the housing and wherein the inner ferrule surface defines a ferrule opening, the ferrule opening extending to spaced apart first and second ferrule end surfaces;

ii) an insulator disposed in the ferrule opening hermetically sealed to the inner ferrule surface, the insulator having at least a first via and a second via, both vias extending to the spaced apart first and second insulator end surfaces disposed proximate the respective first and second ferrule end surfaces;

iii) a first conductive lead wire extending through the first via and hermetically sealed to the insulator;

d) at least one first capacitor mounted to the feedthrough terminal and comprising at least one first active electrode plate spaced apart from at least one first ground electrode plate encased in a dielectric, wherein the first lead wire is electrically connected to the first active electrode plate of the first capacitor with the first ground electrode plate being electrically connected to the ferrule and the AND housing;

e) a second electrically conductive pin extending through the second via and hermetically sealed to the insulator in a non-conductive relation with the ferrule and the AND housing, wherein the second conductive pin has a proximal pin portion spaced from a distal pin portion, the proximal pin portion being electrically connected to the electronic circuit board or substrate disposed within the housing with the distal pin portion extending from the insulator opposite the first capacitor; and

f) a band stop filter, comprising:

i) at least one second active electrode plate electrically connected to the second conductive pin, but spaced from the first lead wire, the second active electrode plate being in a spaced, capacitive relationship within the dielectric with the first ground electrode plate of the first capacitor to thereby form a second capacitor;

ii) an inductor segment extending from a proximal inductor segment end to a distal inductor segment end, wherein the proximal end of the inductor segment and the second active electrode plate are directly electrically connected to the second conductive pin at a first node between the proximal and distal pin portions and wherein the distal end of the inductor segment and the first ground electrode plate are directly electrically connected to the ferrule and then the AMD housing at a second node to thereby provide the band stop filter comprising the inductor segment directly electrically connected from the first node to the second node in parallel with the second capacitor.

2. The active medical device of claim 1 , wherein a Q factor for the inductor is relatively maximized and a Q factor for the 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 the inductor is relatively maximized by minimizing resistive loss in the inductor.

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

5. The active medical device of claim 1 , wherein the AMD is selected from the group consisting of 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.

6. The active medical device of claim 1 wherein the band stop filter is disposed at an inboard side of the hermetic feedthrough terminal.

7. The active medical device of claim 1 wherein the first lead wire is connectable to an electrode that is adapted for contact. with patient tissue.

8. The active medical device of claim 1 further including a second band stop filter comprising a third capacitor in parallel with a second inductor and coupled between the second conductive pin and a ground plane, the second band stop filter having a 3-dB bandwidth in the megahertz range that has a resonant center frequency that is different than that of the first band stop filter.

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

a) a housing for the AMD;

b) an electronic circuit board or substrate disposed on an inboard side opposite an outboard body fluid side of the housing;

c) a hermetic feedthrough terminal, comprising:

i) a ferrule comprising a ferrule sidewall having an outer surface spaced from an inner surface, wherein the outer ferrule surface is hermetically sealed to an opening in the housing and wherein the inner ferrule surface defines a ferrule opening, the ferrule opening extending to spaced apart first and second ferrule end surfaces;

ii) an insulator disposed in the ferrule opening and hermetically sealed to the inner ferrule surface, the insulator having at least a first via and a second via, both vias extending to the spaced apart first and second insulator end surfaces disposed proximate the respective first and second ferrule end surfaces;

iii) a first conductive lead wire extending through the first via and hermetically sealed to the insulator;

d) at least one first capacitor mounted to the feedthrough terminal and comprising at least one first active electrode plate spaced apart from at least one first ground electrode plate encased in a dielectric, wherein the first lead wire is electrically connected to the first active electrode plate of the first capacitor with the first ground electrode plate being electrically connected to the ferrule and the AMD housing;

e) a second electrically conductive pin extending through the second via and hermetically sealed to the insulator in a non-conductive relation with the ferrule and the AMU housing, wherein the second conductive pin has a proximal pin portion spaced from a distal pin portion, the proximal pin portion being electrically connected to the electronic circuit board. or substrate disposed within the housing with the distal pin portion extending from the insulator opposite the first capacitor; and

f) a first band stop filter, comprising:

i) at least one second active electrode plate electrically connected to the second conductive pin, but spaced from the first lead wire, the second. conductive electrode plate being in a spaced, but capacitive relationship within the dielectric with the first ground electrode plate of the first capacitor to thereby form a second capacitor;

ii) an inductor segment extending from a proximal inductor segment end to a distal inductor segment end, wherein the proximal end of the inductor segment and the second active electrode plate are directly electrically connected to the second conductive pin at a first node between the proximal and distal pin portions and wherein the distal end of the inductor segment and the first ground electrode plate are directly electrically connected to the ferrule and then the AMD housing at a second node to thereby provide the band stop filter comprising the inductor segment directly electrically connecting from the first node to the second node in parallel with the second capacitor,

g) wherein the band stop filter has a 3-dB bandwidth in the megahertz range; and

h) a second band stop filter comprising a third capacitor in parallel with a second inductor and coupled between the second conductive pin and a ground plane, the second band stop filter having a 3-dB bandwidth in the megahertz range that has a resonant center frequency that is different than that of the first band stop filter.

10. The active medical device of claim 1 wherein the band stop filter has a 3-dB bandwidth in the megahertz range.

11. The active medical device of claim 10 wherein the 3-dB bandwidth of the band stop filter includes pulsed MRI signals.