Article comprising an inductive element with a magnetic thin film

• US 5,847,634 A
• Filed: 07/30/1997
• Issued: 12/08/1998
• Est. Priority Date: 07/30/1997
• Status: Expired due to Term

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: van Dover, Robert Bruce, Korenivski, Vladislav
• Primary Examiner(s): Gellner, Michael L.
• Assistant Examiner(s): MAI, ANH T
• Application Number:
  US08/902,686
• Time in Patent Office: 496 Days
• Field of Search: 336/175, 336/177, 336/178, 336/200, 336/223, 336/232, 336/234
• US Class Current: 336/200
• CPC Class Codes: H01F 17/0006 Printed inductances printed coils for dynamo-electric machines H02K3/26; printed circuits H05K
• CPC Class Codes: H01F 17/04 with magnetic core

Abstract

A thin film inductive element according to this invention comprises an elongate conductor, and spaced apart magnetic strips that substantially surround the conductor, with dielectric material between the magnetic strips and the conductor. The inductive element can have relatively high inductance and low loss, can be used in linear form, meander on spiral form, or any other desired form, is suitable for use at RF frequencies, and can be integrated with conventional circuitry. Criteria for choosing the length of the magnetic strips and the thickness of the dielectric are disclosed.

Claims

1. An article comprising a substrate having a major surface, with a thin film inductive element thereon, the inductive element comprising an elongate conductor, a multiplicity of spaced apart conductive lower magnetic strips of length l_m disposed on the major surface, and a corresponding multiplicity of spaced apart conductive upper magnetic strips of length l_m, with the elongate conductor disposed between the lower and upper magnetic strips;

space="preserve" listing-type="equation">CHARACTERIZED IN THAT

the inductive element further comprises dielectric material of thickness t_i disposed between the spaced apart lower magnetic strips and the elongate conductor, and between the elongate conductor and the spaced apart upper magnetic strips.

2. Article according to claim 1, wherein t_i is selected such that

3. Article according to claim 1, wherein f_o is in the range 0.1-2.0 GHz, where f_o is a predetermined operating frequency.

4. Article according to claim 1, wherein at least one of the magnetic strips comprises two or more layers of magnetic material, with a dielectric layer between adjacent layers of magnetic material.

5. Article according to claim 1, wherein the thickness of the elongate conductor is at f_o, less than a skin depth of the elongate conductor.

6. Article according to claim 1, wherein the thickness of the magnetic strips is at f_o, less than a skin depth of the magnetic strips.

7. Article according to claim 1, wherein l_m >

50 μ

m, and wherein a spacing between adjacent magnetic strips is less than l_m.

8. Article according to claim 7, wherein the spacing between adjacent magnetic strips is less than 0.25 l_m.

9. Article according to claim 1, wherein the magnetic strips have resistivity greater than 30 μ

Ω

.cm.

10. Article according to claim 1, wherein the inductive element has a meander shape.

11. Article according to claim 1, wherein the substrate is a Si body, with integrated electronic circuitry on the body, and with the inductive element connected to the circuitry.