EMI filter for human implantable heart defibrillators and pacemakers
First Claim
1. A feedthrough capacitor assembly, comprising:
- a substantially monolithic casing of dielectric material having a plurality of conductive electrode plates encased therein in an alternating stack of a plurality of first and second layers in spaced parallel relation;
said first layer including at least one active plate corresponding to at least one feedthrough capacitor, and a first ground plate electrically isolated from said active plate; and
said second layer including a second ground plate common to said at least one of active plate of said first layer and cooperating therewith to define said feedthrough capacitor, and further cooperating with said first ground plate to define a coupling capacitor for coupling said feedthrough capacitor to a common ground point.
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Accused Products
Abstract
An improved ceramic feedthrough capacitor design which results in distinct advantages in EMI (electromagnetic interference) filtering and therapeutic waveform management for implantable defibrillators and pacemakers and the like. The invention provides ceramic capacitor electrode plate designs which provide both low impedance decoupling for EMI suppression, and, at the same time provide an isolated common ground point through a separate coupling capacitor for electrical isolation of the filtered circuit from the metal case (usually titanium) of the defibrillator or the like. Such an arrangement allows the defibrillator HV (high voltage) output pulse to the heart to be referenced lead to lead (including reverse polarity), or from either lead to a common floating ground point or to the titanium case. The primary application of the invention is directed to implantable defibrillators where the output pulse to the heart is typically high voltage (up to 750 volts) and of short duration (typically in the 10×10-3 seconds or 10 millisecond range). The invention is equally applicable to implantable pacemakers. The invention is particularly suited for a combination defibrillator (tachycardia) and pacemaker (bradycardia) unit where there are sense (heart monitoring), low voltage (pacing) and high voltage (defibrillator) output leads.
363 Citations
18 Claims
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1. A feedthrough capacitor assembly, comprising:
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a substantially monolithic casing of dielectric material having a plurality of conductive electrode plates encased therein in an alternating stack of a plurality of first and second layers in spaced parallel relation; said first layer including at least one active plate corresponding to at least one feedthrough capacitor, and a first ground plate electrically isolated from said active plate; and said second layer including a second ground plate common to said at least one of active plate of said first layer and cooperating therewith to define said feedthrough capacitor, and further cooperating with said first ground plate to define a coupling capacitor for coupling said feedthrough capacitor to a common ground point. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification