Noise suppressor

• US 5,500,629 A
• Filed: 03/02/1995
• Issued: 03/19/1996
• Est. Priority Date: 09/10/1993
• Status: Expired due to Term

• Current Assignee: Iowa State University Research Foundation Incorporated (Iowa State University)
• Original Assignee: Greentree Technologies, Inc.
• Inventors: Meyer, Dennis R.
• Primary Examiner(s): GENSLER, PAUL L
• Application Number:
  US08/398,050
• Time in Patent Office: 383 Days
• Field of Search: 333/12, 333/181-185, 361/311, 338/66, 338/20-22 R, 336/175, 336/176, 336/233, 174/32
• US Class Current: 333/181
• CPC Class Codes: H01F 1/344 Ferrites, e.g. having a cubic spinel structure (X2+O)(Y23+O3), e.g. magnetite Fe3O4
• CPC Class Codes: H01F 1/36 in the form of particles H01F1/346, H01F1/348 and H01F1/38 take precedence
• CPC Class Codes: H03H 1/0007 of radio frequency interference filters
• CPC Class Codes: H03H 7/0115 comprising only inductors and capacitors H03H7/075, H03H7/09, H03H7/12, H03H7/13 take precedence

Abstract

A distributed low-pass filter typically attenuating a signal, 7 db. at 10 MHz., 18 db. at 30 MHz., and continuing at 50 db/decade, without resonant inflections, uses a small, low cost, rectangular tubular bead of outside dimension 3 mm.×6 mm.×2 mm., made from a body material having evenly distributed magnetic, dielectric, and resistive properties. A through-conductor completes the distributed filter which acts like a high loss cable transmission line. The tube'"'"'s inner and outer surfaces are separately coated with an electrode material. The through-conductor electrically connects to the inner electrode, with its ends providing first and second filter terminals, and the outer electrode providing a common, terminal. An a.c. signal impressed between the first and common terminals produces an attenuated signal between the second and common terminals in accordance with the above characteristics. Also, a 6 mm.×6 mm.×1 mm block of the body material may typically form a 500 μF power-line, noise suppressor. The above devices may include bi-directional, zener-like, voltage limiter capability; absorbing noise and electrostatic discharges, like varistors. A preferred body material is a sintered mix of oxides of manganese and iron, modified by oxides of zinc, nickel, or other metals. This soft ferrite, ceramic adapts to make surface mounted devices. Small, low cost, RF noise suppressors, line terminators, or impedance matching filters for use in high frequency (baud rate) cable connectors may be molded individually, or integrated as multiple devices.

Claims

1. An electrical noise suppressing component comprising:

a) a body made from a sintered polycrystalline body material having cohesively integrated metal oxide grains, wherein magnetic, dielectric, and resistive properties are substantially evenly distributed throughout the body, providing a minimum body permittivity of 4,000,000 at 1 KHz, and a body resistivity less than 1 MΩ

per cm.;

b) at least one noise suppressing element formed by the body, comprising a first surface being separated from a second surface by an intermediate section of the body material;

c) a first electrode disposed upon the first surface, defining a first area of electrical contact with the intermediate section;

d) a second electrode disposed upon the second surface, defining a second area of electrical contact with the intermediate section.

2. The electrical noise suppressing component recited in claim 1 wherein the body material has a finished grain molecular weight distribution of:

36 to 57% MnO, 45 to 56% Fe₂ O₃, 0 to 12% ZnO, and 0 to 0.2% of at least one additive element selected from the group consisting of Al₂ O₃, CaO, CoO, CuO, Na₂ O, NiO, SiO₂, PbO.

3. The electrical noise suppressing component recited in claim 2 wherein the body material includes a non-linear conductance property such that when a voltage in excess of a specified threshold voltage level is impressed between the first and second electrodes of the noise suppressing element the resistivity of the body material in the intermediate section will reduce in an avalanching manner.

4. The electrical noise suppressing component recited in claim 1, wherein said at least one noise suppressing element comprises a plurality of the noise suppressing elements formed by the body.

5. The electrical noise suppressing component recited in claim 1, wherein the body material is porous.

6. The electrical noise suppressing component recited in claim 1, wherein the intermediate section of the noise suppressing element is shaped as an elongated tube having an inner peripheral surface, being the second surface, and an outer peripheral surface being the first

surface, the first and second surfaces being coaxial, the noise suppressing element having a noise suppressing characteristic substantially defined by the axial length over which the first and second areas of electrical contact with the intermediate section are coextensive.

7. The electrical noise suppressing component of claim 6, further comprising a through-conductor having an input end, and an output end, extending through the elongated tube proximate, and electrically connected to the second electrode of the noise suppressing element.

8. The electrical noise suppressing component recited in claim 7, wherein the noise suppressing component includes means for mechanically adjusting the axial distance over which the first and second electrodes of the noise suppressing element are coextensive.

9. An electrical noise suppressing component comprising:

a) a body made from a sintered polycrystalline body material having cohesively integrated metal oxide grains, wherein magnetic, dielectric, and resistive properties are substantially evenly distributed throughout the body, providing a minimum body permittivity of 4,000,000 at 1 KHz, and a body resistivity less than 1 MΩ

per cm.;

b) an outer electrode being disposed on the outer peripheral surface of the body;

c) a plurality of coextensive, axially parallel, passages formed through the body, wherein the body material surrounding each individual passage, forms an individual inner peripheral passage surface;

d) a plurality of inner electrodes of equal number to the number of passages, wherein each one of the inner electrodes is disposed on and relates to one of the passage'"'"'s surfaces, one inner electrode for one passage surface;

e) a means for electrically insulating each inner electrode preventing direct electrical connection with any of the other inner electrodes and from direct electrical connection with the outer electrode.

10. The electrical noise suppressing component as recited in claim 9 further comprising:

a) a plurality of through-conductors of equal number to that of the number of passages, each of the through-conductors individually having an input end and an output end;

b) each one of the through-conductors being related to, associated with, and extending through, one of the passages, wherein it fits proximate to the passage surface, and is electrically connected to the inner electrode of the passage.

11. A noise suppressor assembly having a through-passage comprising:

a) a plurality of noise suppressor devices;

b) each said noise suppressor device comprising;

i) a body made from a sintered polycrystalline body material having cohesively integrated metal oxide grains, wherein magnetic, dielectric, and resistive properties are substantially evenly distributed throughout the body, providing a minimum body permittivity of 4,000,000 at 1 KHz, and a body resistivity less than 1 MΩ

per cm.; and

ii) said body having a first surface and a second surface, said first surface separated from said second surface by an intermediate section of said body material, a first electrode disposed upon said first surface, a second electrode disposed upon said second surface; and

iii) said body being shaped to form a segment of said noise suppressor assembly, having at least two contact surfaces;

c) each of said noise suppressor devices joining with the other said noise suppressor devices in said noise suppressor assembly via said contact surfaces;

d) said noise suppressor assembly having an inner peripheral surface adjacent said through-passage and an outer peripheral surface, said inner and outer peripheral surfaces being coaxial;

e) said second surfaces of the noise suppressing devices substantially forming said inner peripheral surface;

f) said first surfaces of said noise suppressing elements substantially forming said outer peripheral surface of said filter assembly.

12. The filter assembly of claim 11 further comprising:

a) said first electrodes of each of said noise suppressing devices of said noise suppressor assembly electrically connected to a common connection terminal;

b) a through-conductor having an input end and an output end extending through said through-passage, wherein said through-conductor fits proximate said inner peripheral surface, and is electrically connected to said second electrode of each and every one of said noise suppressor devices.