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, comprising:
a) at least one implantable lead wire 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) at least one electrode electrically connected to either the distal lead wire portion or the distal lead wire end, wherein the electrode is configured to be contactable with biological tissue; and c) a wound portion of the lead wire providing a self-resonant inductor having an inductance disposed physically and electrically in series at or proximally adjacent to the at least one electrode, d) wherein, along with a capacitive series resistance (RC) and an inductor series resistance (RL), the self-resonant inductor has sufficient parasitic capacitance between adjacent turns of the wound lead wire so that at frequencies of about 10 Hz to about 1 kHz, an inductive reactance and the inductor series resistance (RL) permit passage of biological signals from the electrode to the proximal lead wire end while a capacitive reactance and the capacitive series resistance (RC) substantially act as an open circuit to the same biological signals that the inductive reactance and the inductor series resistance (RL) permit to pass, and e) wherein the inductance ranges from 1 to 4,000 nanohenries and the parasitic capacitance ranges from 0.1 to 20,000 picofarads, and f) wherein the total parasitic capacitance C, the capacitive series resistance (RC), the inductance L, and the inductor series resistance (RL) provide the self-resonant inductor having a quality factor Q that results in a 3-dB bandwidth that is at least a MHz, and g) wherein the self-resonant inductor has an equivalent L-C resonant electrical circuit comprising a total capacitance in series with the capacitive series resistance (RC) which are both in parallel with a total inductance in series with the inductor series resistance (RL).