RF filter for an active medical device (AMD) for handling high RF power induced in an associated implanted lead from an external RF field
First Claim
1. A hermetically sealed feedthrough filter assembly for an implantable medical device, the feedthrough filter assembly comprising:
- a) an electrically conductive ferrule defining a ferrule opening, wherein the ferrule is configured to be attachable to an opening in a housing of an active implantable medical device;
b) an insulator at least partially residing in the ferrule opening where a hermetic seal connects the insulator to the ferrule, wherein the insulator extends from an insulator body fluid side to an insulator device side with an insulator via hole extending through the insulator to the insulator body fluid and device sides;
c) a conductive pathway hermetically sealed to the insulator in the via hole, the conductive pathway extending from a conductive pathway body fluid side to a conductive pathway device side, wherein the conductive pathway is in a non-conductive relation with the ferrule;
d) a filter capacitor, comprising;
i) a ceramic dielectric body having a dielectric constant that is greater than zero, but less than 1,000; and
ii) at least two active electrode plates interleaved with at least two ground electrode plates supported in the ceramic dielectric body;
e) a first conductive structure electrically connecting the at least two active electrode plates to the conductive pathway device side; and
f) a second conductive structure electrically connecting the at least two ground electrode plates to the ferrule,g) wherein the filter capacitor has;
i) a capacitance that ranges from 10 and 20,000 picofarads, andii) an equivalent series resistance (ESR), which is the sum of a dielectric loss plus an ohmic loss of the ceramic dielectric body, that is greater than zero, but less than 2.0 ohms at an MRI RF pulsed frequency or at a range of MRI RF pulsed frequencies,h) wherein the filter capacitor is the first filter capacitor electrically connected to the conductive pathway device side and to the ferrule.
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Accused Products
Abstract
An AIMD includes a conductive housing, an electrically conductive ferrule with an insulator hermetically sealing the ferrule opening. A conductive pathway is hermetically sealed and disposed through the insulator. A filter capacitor is disposed within the housing and has a dielectric body supporting at least two active and two ground electrode plates interleaved, wherein the at least two active electrode plates are electrically connected to the conductive pathway on the device side, and the at least two ground electrode plates are electrically coupled to either the ferrule and/or the conductive housing. The dielectric body has a dielectric constant less than 1000 and a capacitance of between 10 and 20,000 picofarads. The filter capacitor is configured for EMI filtering of MRI high RF pulsed power by a low ESR, wherein the ESR of the filter capacitor at an MRI RF pulsed frequency or range of frequencies is less than 2.0 ohms.
42 Citations
39 Claims
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1. A hermetically sealed feedthrough filter assembly for an implantable medical device, the feedthrough filter assembly comprising:
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a) an electrically conductive ferrule defining a ferrule opening, wherein the ferrule is configured to be attachable to an opening in a housing of an active implantable medical device; b) an insulator at least partially residing in the ferrule opening where a hermetic seal connects the insulator to the ferrule, wherein the insulator extends from an insulator body fluid side to an insulator device side with an insulator via hole extending through the insulator to the insulator body fluid and device sides; c) a conductive pathway hermetically sealed to the insulator in the via hole, the conductive pathway extending from a conductive pathway body fluid side to a conductive pathway device side, wherein the conductive pathway is in a non-conductive relation with the ferrule; d) a filter capacitor, comprising; i) a ceramic dielectric body having a dielectric constant that is greater than zero, but less than 1,000; and ii) at least two active electrode plates interleaved with at least two ground electrode plates supported in the ceramic dielectric body; e) a first conductive structure electrically connecting the at least two active electrode plates to the conductive pathway device side; and f) a second conductive structure electrically connecting the at least two ground electrode plates to the ferrule, g) wherein the filter capacitor has; i) a capacitance that ranges from 10 and 20,000 picofarads, and ii) an equivalent series resistance (ESR), which is the sum of a dielectric loss plus an ohmic loss of the ceramic dielectric body, that is greater than zero, but less than 2.0 ohms at an MRI RF pulsed frequency or at a range of MRI RF pulsed frequencies, h) wherein the filter capacitor is the first filter capacitor electrically connected to the conductive pathway device side and to the ferrule. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An active implantable medical device (AIMD), comprising:
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a) a conductive housing defining a body fluid side and a device side, wherein the body fluid side is located outside the conductive housing and the device side is located inside the conductive housing; b) an electrically conductive ferrule sealed in a housing opening in the conductive housing, the ferrule having a ferrule opening extending from a ferrule body fluid side to a ferrule device side; c) an insulator at least partially residing in the ferrule opening where a hermetic seal connects the insulator to the ferrule, wherein the insulator comprises at least one insulator via hole extending from a via body fluid side to a via device side; d) a conductive pathway hermetically sealed to the insulator in the via hole, the conductive pathway extending from a conductive pathway body fluid side to a conductive pathway device side, wherein the conductive pathway is in a non-conductive relation with the ferrule and the conductive housing; e) a filter capacitor located inside the conductive housing and comprising; i) a ceramic dielectric body having a dielectric constant that is greater than zero, but less than 1,000; and ii) at least two active electrode plates interleaved with at least two ground electrode plates supported in the ceramic dielectric body; f) a first conductive structure electrically connecting the at least two active electrode plates to the conductive pathway device side; and g) a second conductive structure electrically connecting the at least two ground electrode plates to either the ferrule or the conductive housing or, to both the ferrule and the conductive housing; h) a circuit board located on the device side, inside the conductive housing, wherein the filter capacitor is mounted to the circuit board so that the filter capacitor is the first filter capacitor electrically connected to the conductive pathway device side and to the ferrule or the housing or, to both the ferrule and the housing; i) wherein the filter capacitor has; i) a capacitance that ranges from 10 to 20,000 picofarads, ii) an equivalent series resistance (ESR), which is the sum of a dielectric loss plus an ohmic loss of the ceramic dielectric body, that is greater than zero, but less than 0.1 ohms at an MRI RF pulsed frequency of 64 MHz or 128 MHz or, at a range of MRI RF pulsed frequencies centered at about 64 MHz or 128 MHz, and iii) a dielectric loss tangent, measured in ohms at either one of the MRI RF pulsed frequencies of 64 MHz or 128 MHz or, at the range of MRI RF pulsed frequencies centered at 64 MHz or 128 MHz, that is greater than zero, but less than five percent of the ESR of the filter capacitor. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. An active implantable medical device (AIMD), comprising:
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a) a conductive housing defining a body fluid side and a device side, wherein the body fluid side is located outside the conductive housing and the device side is located inside the conductive housing; b) an electrically conductive ferrule sealed in a housing opening in the conductive housing, the ferrule having a ferrule opening extending from a ferrule body fluid side to a ferrule device side; c) an insulator disposed in and hermetically sealed to the ferrule in the ferrule opening, wherein the insulator comprises at least one insulator via hole extending from a via body fluid side, adjacent to the ferrule body fluid side, to a via device side, adjacent to the ferrule device side; d) a conductive pathway hermetically sealed to the insulator in the via hole, the conductive pathway extending from a conductive pathway body fluid side, adjacent to the ferrule body fluid side, to a conductive pathway device side, adjacent to the ferrule device side, wherein the conductive pathway is in a non-conductive relation with the ferrule and the conductive housing; and e) a filter capacitor located inside the conductive housing, wherein the filter capacitor comprises; i) a ceramic dielectric body having a dielectric constant that is greater than zero, but less than 1,000; ii) at least two active electrode plates interleaved with at least two ground electrode plates supported in the ceramic dielectric body, and wherein the filter capacitor has; iii) a capacitance that ranges from 10 to 20,000 picofarads; and iv) an equivalent series resistance (ESR), which is the sum of a dielectric loss plus an ohmic loss of the ceramic dielectric body, that is greater than zero, but less than 2.0 ohms at an MRI RF pulsed frequency or at a range of MRI RF pulsed frequencies; f) a first conductive structure electrically connecting the at least two active electrode plates to the conductive pathway device side, g) a second conductive structure electrically connecting the at least two ground electrode plates to the ferrule or to the conductive housing or, to both the ferrule and the conductive housing; and h) at least one diode electrically connected in parallel with the filter capacitor between the conductive pathway device side and the ferrule or the conductive housing or, between the conductive pathway device side and both the ferrule and the conductive housing, i) wherein the filter capacitor is the first filter capacitor electrically connected to the conductive pathway device side and to the ferrule or the device housing or, to both the ferrule and the device housing. - View Dependent Claims (34, 35, 36, 37, 38, 39)
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Specification