EMI FILTER EMPLOYING A SELF-RESONANT INDUCTOR BANDSTOP FILTER HAVING OPTIMUM INDUCTANCE AND CAPACITANCE VALUES

摘要

A bandstop filter having optimum component values is provided for a lead of an active implantable medical device (AIMD). The bandstop filter includes a capacitor in parallel with an inductor. The parallel capacitor and inductor are placed in series with the implantable lead of the AIMD, wherein values of capacitance and inductance are selected such that the bandstop filter is resonant at a selected frequency. The Q of the inductor may be relatively maximized and the Q of the capacitor may be relatively minimized to reduce the overall Q of the bandstop filter to attenuate current flow through the implantable lead along a range of selected frequencies.

主权项

1. An implantable lead wire, comprising:
a) a length extending from a proximal lead wire end to a distal lead wire portion having a distal lead wire end, wherein the proximal lead wire end is electrically connectable to electronic circuits of an active implantable medical device; b) an electrode electrically connected to either the distal lead wire portion or the distal lead wire end, wherein the electrode is contactable to biological tissue; and c) at least one bandstop filter comprising a coiled self-resonant inductor having parasitic capacitance between its adjacent turns, the bandstop filter comprising at least a portion of the lead with the self-resonant inductor being physically and electrically connected in series with the lead wire and in series with the electrode, d) wherein the self-resonant inductor has an inductance (L) and an inductor series resistance (RL), and wherein the inductance ranges from 1 to 4,000 nanohenries to thereby permit passage of biological signals along the lead wire at frequencies of about 10 Hz to about 1 kHz, and e) wherein the parasitic capacitance has a total equivalent capacitance (C) and a capacitor series resistance (RC), and wherein the total equivalent capacitance ranges from 0.1 to 20,000 picofarads to thereby substantially act as an open circuit to the same biological signals at frequencies of about 10 Hz to about 1 kHz that the inductance allows to pass along the lead wire, and f) wherein the total equivalent capacitance C, the capacitor series resistance RC, the inductance L, and inductor series resistance RL provide the bandstop filter having a Q with a 3 db bandwidth that is on the order of MHz.