Self-shielding inductor

• US 7,501,924 B2
• Filed: 09/30/2005
• Issued: 03/10/2009
• Est. Priority Date: 09/30/2005
• Status: Expired due to Fees

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Zhang, Ligang
• Primary Examiner(s): Mai; Anh T
• Application Number:
  US11/239,933
• Publication Number:
  US 20070075813A1
• Time in Patent Office: 1,257 Days
• Field of Search: 336/200, 336/223, 336/232, 257/686, 257659-660
• US Class Current: 336/200
• CPC Class Codes: H01F 2017/004 with the coil helically wound around an axis without a core
• CPC Class Codes: H01F 2017/008 Electric or magnetic shielding of printed inductances
• CPC Class Codes: H01F 27/36 Electric or magnetic shields or screens movable for varying inductance H01F21/10
• CPC Class Codes: H01F 27/363 made of electrically conductive material

Abstract

An oscillator circuit formed at least partially on an integrated circuit substrate includes a self-shielding inductor. The self-shielding inductor has a toroidal structure. A coil forms a structure that is symmetric around an axis orthogonal to a surface of the integrated circuit substrate. A magnetic filed generated by the self-shielding inductor is confined to a core region of the coil. Portions of the self-shielding inductor may be formed in integrated circuit layers, redistribution layers, package layers, through-substrate interconnect, backside substrate conductor layers, or combinations thereof.

Claims

1. An apparatus comprising:

a self-shielding inductor forming at least a portion of an oscillator circuit, the self-shielding inductor including a coil of coupled conductor portions, the coil being formed around an axis and the coupled conductor portions substantially enclosing a core region within the coil,

wherein the axis is coplanar with cross-sections of the coil and is external to cross-sections of the coil,

wherein less than approximately one complete turn forms the coil.

2. The apparatus, as recited in claim 1, further comprising:

an integrated circuit that includes at least a portion of the self-shielding inductor, an amplifier coupled to the self-shielding inductor, and a capacitor coupled to the self-shielding inductor,

wherein the self-shielding inductor, the amplifier, and the capacitor form at least a portion of the oscillator circuit.

3. The apparatus, as recited in claim 1, wherein the coil forms a perimeter of a substantially symmetric polygonal center of the self-shielding inductor.

4. The apparatus, as recited in claim 1, wherein the coil comprises:

first, second, third, and fourth portions,

wherein the first portion of the coil is parallel to the second portion of the coil, the first and second portions of the coil being approximately equidistant from the axis, and the first and second portions of the coil being coupled to conduct substantially equal currents in substantially opposite directions, and

wherein the third portion of the coil is parallel to the fourth portion of the coil, the third and fourth portions of the coil being approximately equidistant from the axis, and the third and fourth portions of the coil being coupled to conduct substantially equal currents in substantially opposite directions.

5. The apparatus, as recited in claim 1, wherein substantially equal and substantially opposite magnetic fields are generated parallel to a first plane intersecting the axis in corresponding portions of the core region in response to a current flowing though corresponding coupled conductor portions and substantially equal and substantially opposite magnetic fields are generated parallel to at least a second plane intersecting the axis in corresponding portions of the core region in response to a current flowing though corresponding coupled conductor portions.

6. The apparatus, as recited in claim 1, wherein the self-shielding inductor is formed at least partially on the backside of an integrated circuit substrate.

7. The apparatus, as recited in claim 1, wherein the self-shielding inductor is formed at least partially in a redistribution layer.

8. The apparatus, as recited in claim 1, wherein the self-shielding inductor has an associated quality factor in a range of approximately 8 to approximately 130 at approximately 5 GHz or greater, inclusively.

9. The apparatus, as recited in claim 1, wherein a number of turns forming the coil is in a range from one turn to approximately twenty turns, inclusively.

10. The apparatus, as recited in claim 1, wherein the oscillator circuit includes a capacitance coupled in parallel with the self-shielding inductor, the capacitance being formed to provide a current path having a current distribution effectively the same as the coupled conductor portions.

11. The apparatus, as recited in claim 1, wherein the oscillator circuit includes an amplifier coupled in parallel with the self-shielding inductor, the amplifier being formed to provide a current path having a current distribution effectively the same as the coupled conductor portions.

12. The apparatus, as recited in claim 1, wherein the coil includes up to a single turn and a current path of the turn is formed in the approximate center of the self-shielding inductor.

13. The apparatus, as recited in claim 1, wherein inner sidewalls of the self-shielding inductor are formed by at least a column of stacked via structures.

14. The apparatus, as recited in claim 1, wherein the self-shielding inductor is formed entirely within an integrated circuit.

15. The apparatus, as recited in claim 1, wherein at least a portion of the self-shielding inductor is formed in at least one redistribution layer.

16. The apparatus, as recited in claim 1, wherein at least a portion of the self-shielding inductor is formed in at least one layer of a package surrounding an integrated circuit.

17. The apparatus, as recited in claim 1, wherein the core region includes at least predominately, substantially non-magnetic layers.

18. The apparatus, as recited in claim 1, wherein the core region includes at least predominately dielectric material.

19. The apparatus, as recited in claim 1, wherein the coupled conductor portions of the coil include at least a first sidewall conductor portion, a second sidewall conductor portion, and a top conductor portion coupling the first and second sidewall conductor portions, at least one of the first and second sidewalls being formed at least in part by discrete via structures in an integrated circuit.

20. The apparatus, as recited in claim 19, wherein the discrete via structures are staggered.

21. The apparatus, as recited in claim 19, wherein the discrete via structures include a thru-substrate via.

22. The apparatus, as recited in claim 1,

wherein the coupled conductor portions of the coil include at least a first sidewall conductor portion, a second sidewall conductor portion, and a top conductor portion coupling the first and second sidewall conductor portions, and

wherein at least one of the first and second sidewall conductor portions are formed at least in part by discrete via structures in an integrated circuit and at least one of the top conductor portion and a bottom conductor portion is formed at least in part by a plurality of conductive lines, at least one of the plurality of conductive lines being formed in a first metal layer and at least one of the plurality of metal lines being formed in a second metal layer, the conductive lines in the first metal layer being coupled to and staggered from the conductive lines in the second metal layer.

23. The apparatus, as recited in claim 19, wherein at least one of the top conductor portion and a bottom conductor portion is formed by a substantially solid conductive layer.

24. An apparatus comprising:

a self-shielding inductor forming at least a portion of an oscillator circuit, the self-shielding inductor including a coil of coupled conductor portions, the coil being formed around an axis and the coupled conductor portions substantially enclosing a core region within the coil,

wherein the axis is coplanar with cross-sections of the coil and is external to cross-sections of the coil,

wherein inner sidewalls of the self-shielding inductor are formed in the approximate center of the self-shielding inductor.

25. The apparatus, as recited in claim 24, wherein less than approximately one complete turn forms the coil.

26. An apparatus comprising:

a first node on an integrated circuit die;

a second node on the integrated circuit die;

a capacitor coupling the first node to the second node;

an amplifier coupled between the first node and the second node; and

means for generating a magnetic field in response to a current flowing between the first node and the second node,

wherein the means for generating confines the magnetic field to a substantially enclosed region of the generating means,

wherein the means for generating comprises a coil having less than approximately one complete turn.