Planar magnetic frame inductors having open cores

• US 6,573,818 B1
• Filed: 03/31/2000
• Issued: 06/03/2003
• Est. Priority Date: 03/31/2000
• Status: Expired due to Term

• Current Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Inventors: Klemmer, Timothy J., Ellis, Kenneth Alexander, Lotfi, Ashraf Wagih, Van Dover, Robert Bruce
• Primary Examiner(s): Nguyen, Tuyen T.
• Application Number:
  US09/540,618
• Time in Patent Office: 1,159 Days
• Field of Search: 336/65, 336/83, 336/200, 336/223, 336/232, 257/531
• US Class Current: 336/83
• CPC Class Codes: H01F 17/0006 Printed inductances printed coils for dynamo-electric machines H02K3/26; printed circuits H05K
• CPC Class Codes: H01F 2027/2819 Planar transformers with printed windings, e.g. surrounded by two cores and to be mounted on printed circuit
• CPC Class Codes: H01F 27/245 made from sheets, e.g. grain-oriented H01F27/26 takes precedence
• CPC Class Codes: H01F 27/2804 Printed windings

Abstract

The present invention is a planar spiral inductor a top magnetic layer a bottom magnetic layer; and a plurality of conductive coils disposed between said top magnetic layer and said bottom magnetic layer. A significant difference from prior art is that the top and bottom magnetic layers have their centers effectively cut out using lithographic techniques or other techniques to frame the core of the conductive spirals. An advantage of this structure over the prior art is that when magnetic anisotropies other than shape are kept small, then the magnetic configuration will produce a magnetostatic shape anisotropy such that the easy axis (low energy direction of magnetization) lies parallel to the legs of a rectangular frame or the circumference of a circular frame, as will be described. During operation of the inductor, the field produced by the coils flows in a radial direction and will be perpendicular to the easy axis direction thereby causing magnetization reversal to occur by rotation while advantageously utilizing the full structure in this mode.

Claims

1. A generally planar inductor device, comprising:

a top magnetic layer;

a bottom magnetic layer; and

a plurality of conductive coils disposed between said top and bottom magnetic layers, each of said top and bottom magnetic layers having an inner circumference parallel to an outer circumference, a width between the inner and outer circumferences being substantially smaller than the inner circumference, wherein said conductive coils produce a magnetic field flowing in a radial direction thereof.

2. The device of claim 1, wherein said top and bottom magnetic layer define an open core in said inductor device.

3. The device of claim 1, wherein said top and bottom magnetic layer are magnetic films.

4. The device of claim 1, wherein said top and bottom magnetic layers and said conductive coils are generally rectangular in shape.

5. The device of claim 1, wherein said top and bottom magnetic layers and said conductive coils are generally circular in shape.

6. The device of claim 1, wherein said conductive coils define a configuration selected from the group consisting of hoop type and spiral type.

7. A generally planar inductor device, comprising:

a top magnetic film layer;

a bottom magnetic film layer; and

a plurality of conductive coils disposed between said top and bottom layers, each of said top and bottom magnetic layers having an inner circumference parallel to an outer circumference, a width between the inner and outer circumferences being substantially smaller than the inner circumference, wherein said top and bottom layers define an open center region therein, said top and bottom layers frame said conductive coils to produce a magnetostatic shape anisotropy on said top and bottom layers such that a low energy direction of magnetization lies parallel to circumferences of said top and bottom layers.

8. The device of claim 7, wherein said top and bottom magnetic layers and said conductive coils are generally rectangular in shape.

9. The device of claim 7, wherein said top and bottom magnetic layers and said conductive coils are generally circular in shape.

10. The device of claim 7, wherein said conductive coils define a configuration selected from the group consisting of hoop type, spiral type and meander type.