RF FILTER FOR AN ACTIVE MEDICAL DEVICE (AMD) FOR HANDLING HIGH RF POWER INDUCED IN AN ASSOCIATED IMPLANTED LEAD FROM AN EXTERNAL RF FIELD

摘要

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.

主权项

1. An active implantable medical device (AIMD), comprising:
a) a conductive housing defining a body fluid side located outside the conductive housing and defining a device side located inside the conductive housing; b) an electrically conductive ferrule hermetically sealed to a housing opening in the conductive housing, the ferrule having a ferrule opening passing through the ferrule between the body fluid side and the device side; c) an insulator hermetically sealing the ferrule opening; d) a conductive pathway hermetically sealed and disposed through the insulator between the body fluid side and the device side, the conductive pathway in non-conductive relation with the ferrule, and the conductive pathway on the body fluid side connectable to an implantable lead conductor having at least one electrode; and e) a filter capacitor disposed within the conductive housing on the device side, the filter capacitor comprising:
i) a capacitance of between 10 and 20,000 picofarads;ii) a dielectric body supporting at least two of active electrode plates interleaved with at least two ground electrode plates, 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;iii) wherein the dielectric body comprises a dielectric constant less than 1000;iv) wherein the filter capacitor is configured for EMI filtering of MRI high RF pulsed power by a low equivalent series resistance (ESR), wherein the ESR is the sum of a dielectric loss plus an ohmic loss, wherein the ESR of the filter capacitor at an MRI RF pulsed frequency or range of frequencies is less than 2.0 ohms.