Apparatus for generating a magnetic interface and applications of the same

• US 20030043077A1
• Filed: 08/23/2002
• Published: 03/06/2003
• Est. Priority Date: 08/23/2001
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Alexopoulos, Nicolaos G., Kyriazidou, Chryssoula, Contopanagos, Harry
• Granted Patent: US 6,906,682 B2
• Time in Patent Office: Days
• US Class Current: 343/700MS
• CPC Class Codes: H01P 1/2005 Electromagnetic photonic bandgaps [EPB], or photonic bandgaps [PBG]
• CPC Class Codes: H01P 3/08 Microstrips; Strip lines
• CPC Class Codes: H01Q 15/002 said selective devices being reconfigurable or tunable, e.g. using switches or diodes
• CPC Class Codes: H01Q 15/0066 said selective devices being reconfigurable, tunable or controllable, e.g. using switches
• CPC Class Codes: H01Q 15/008 said selective devices having Sievenpipers' mushroom elements
• CPC Class Codes: H01Q 21/062 using dipole aerials; H01Q21/067, H01Q21/068 take precedence
• CPC Class Codes: H01Q 9/0407 Substantially flat resonant element parallel to ground plane, e.g. patch antenna dipole H01Q9/285; monopole H01Q9/40
• CPC Class Codes: H01Q 9/27 Spiral antennas

Abstract

A magnetic interface generator generates a magnetic interface at a center frequency f₀. The magnetic interface generator is a passive array of spirals that are deposited on a substrate surface. The magnetic interface is generated in a plane at a distance Z above the surface of the substrate. The distance Z where the magnetic interface is created is determined by the cell size of the spiral array, where the cell size is based on the spiral arm length and the spacing S between the spirals. The center frequency of the magnetic interface is determined by the average track length D_AV of the spirals in the spiral array. In embodiments, the spiral array is one sub-layer in a multi-layer substrate. The spacing S of the spiral array is chosen to project the magnetic interface to another layer in the multi-layer substrate so as to improve performance of a circuit in the plane of the magnetic interface. For example, the magnetic interface can be used to increase the inductance of a printed inductor circuit, and to increase the gain and match of a microstrip patch antenna. Furthermore, the magnetic interface reduces the traverse electric (TE) and transverse magnetic (TM) surface waves in the plane of the magnetic interface, which reduces unwanted coupling between transmission lines.

Claims

1. A circuit that generates a magnetic interface at a center frequency f₀ comprising:

a substrate having a first surface and a second surface, wherein said first surface is coupled to a ground node; and

an array of spirals deposited on said second surface of said substrate, wherein each spiral has an average track length D_AV that is based the center frequency f₀ of the magnetic interface.

2. The circuit of claim 1, wherein said average track length D_AV is determined according to the following:

3. The circuit of claim 1, wherein a first terminal and a second terminal of each spiral is open circuited.

4. The circuit of claim 1, wherein said array of spirals generates said magnetic interface at a distance Z above said second surface, wherein said distance Z is determined based on a spacing S between said spirals.

5. The circuit of claim 1, wherein said array of spirals generates said magnetic interface at a distance Z above said first surface, where said distance Z is determined based on a cell size of said array of spirals, wherein said cell size includes a length L of a spiral and a spacing S of said spiral.

6. The circuit of claim 1, wherein said array of spirals include metallization that is printed on said substrate.

7. A device, comprising:

a substrate layer having a first surface and a second surface, wherein said first surface is coupled to a ground node;

a spiral layer having an array of spirals, printed on said second surface of said substrate, that generates a magnetic interface above said second surface at a center frequency f₀; and

wherein said center frequency f₀ for the magnetic interface is determined by an average track length D_AV for said spirals.

8. The device of claim 7, wherein f₀ is determined according to the following equation:

9. The device of claim 7, wherein a first terminal and a second terminal of each spiral in said array of spirals is open circuited.

10. The device of claim 7, wherein said magnetic interface is generated at a distance Z above said second surface of said substrate, wherein said distance Z is determined based on a cell size of a spiral in said array of spirals.

11. The device of claim 7, further comprising:

a second substrate layer having a first surface coupled to said array of spirals and a second surface; and

a circuit that is printed on said second surface of said second substrate.

12. The device of claim 11, wherein said magnetic interface is generated approximately in a plane of said second surface of said second substrate.

13. The device of claim 11, wherein said circuit is a passive circuit.

14. The device of claim 11, wherein said circuit is an active circuit.

15. The device of claim 11, wherein said circuit includes an inductor.

16. The device of claim 11, wherein said circuit includes a pair of transmission lines.

17. The device of claim 16, wherein said pair of transmission lines are a pair of microstrip lines.

18. The device of claim 11, wherein a cell size of said spirals is adapted so that said magnetic interface is generated approximately in a plane of said circuit.

19. The device of claim 18, wherein said cell size is determined by a length L of a spiral arm and a spacing S between said spirals.

20. A device, comprising:

a ground layer;

a first substrate layer having a first surface and a second surface, said first surface coupled to said ground layer;

a spiral layer having an array of spirals that are printed on said second surface of said first substrate layer;

a second substrate layer having a first surface and a second surface, said first surface of said second substrate layer coupled to said spiral layer;

a circuit printed on a second surface of said second substrate layer; and

wherein said spiral layer generates a magnetic interface centered at a frequency f₀ in a plane of said circuit, and wherein said center frequency f₀ is determined by an average track length D_AV of said spirals.

21. The device of claim 20, wherein said average track length D_AV is determined according to the following equation:

22. The device of claim 20, wherein a cell size of said array of spirals is based on a thickness of said second substrate layer, wherein said cell size includes a length L of a spiral arm and a spacing S between adjacent spirals.

23. The device of claim 20, wherein said terminals of said spirals are open circuited.

24. The device of claim 20, wherein said circuit is an inductor.

25. The device of claim 20, wherein said circuit includes at least two transmission lines.

26. The device of claim 20, wherein said transmission lines are microstrip lines.