Method of and inductor layout for reduced VCO coupling

• US 20050195063A1
• Filed: 08/16/2004
• Published: 09/08/2005
• Est. Priority Date: 03/03/2004
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Mattsson, Thomas
• Granted Patent: US 7,151,430 B2
• Time in Patent Office: Days
• US Class Current: 336/225
• CPC Class Codes: H01F 17/0006 Printed inductances printed coils for dynamo-electric machines H02K3/26; printed circuits H05K
• CPC Class Codes: H01F 2017/0073 with a special conductive pattern, e.g. flat spiral
• CPC Class Codes: H01F 27/346 Preventing or reducing leakage fields using magnetic shields H01F27/36; using auxiliary windings H01F27/38

Abstract

Method and system are disclosed for reducing mutual EM coupling between VCO resonators and for implementing the same on a single semiconductor chip. The method and system involve using inductors that are substantially symmetrical about their horizontal and/or their vertical axes and providing current to the inductors in a way so that the resulting magnetic field components tend to cancel each other by virtue of the symmetry. In addition, two such inductors may be placed near each other and oriented in a way so that the induced current in the second inductor due to the magnetic field originating from first inductor is significantly reduced. The inductors may be 8-shaped, four-leaf clover-shaped, single-turn, multi-turn, rotated relative to one another, and/or vertically offset relative to one another. This Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Claims

1. An inductor layout having reduced mutual electromagnetic coupling, comprising:

a first inductor having a shape that is substantially symmetrical about a first predefined axis, said shape causing said first inductor to have a reduced electromagnetic field at a certain distance from said first inductor, at least in some directions; and

a second inductor positioned at a predetermined distance from said first inductor, wherein a mutual electromagnetic coupling between said first inductor and said second inductor is reduced as a result of said first inductor having a reduced electromagnetic field.

2. The inductor layout according to claim 1, wherein said first inductor and said second inductor are formed on a single semiconductor die.

3. The inductor layout according to claim 1, wherein said first inductor and said second inductor are oriented in a same direction.

4. The inductor layout according to claim 1, wherein said first inductor and said second inductor are oriented in different directions.

5. The inductor layout according to claim 1, wherein said first inductor and said second inductor share a common axis.

6. The inductor layout according to claim 1, wherein said first inductor and said second inductor share no common axis.

7. The inductor layout according to claim 1, wherein said first inductor and said second inductor are substantially 8-shaped.

8. The inductor layout according to claim 7, further comprising an inner loop within each outer loop of said substantially 8-shaped first and second inductors.

9. The inductor layout according to claim 1, wherein said first inductor and said second inductor are substantially four-leaf clover-shaped.

10. The inductor layout according to claim 1, wherein said first inductor and said second inductor are symmetrical about a second predefined axis.

11. A method of reducing mutual electromagnetic coupling between two inductors on a semiconductor die, comprising:

forming a first inductor on said semiconductor die having a shape that is substantially symmetrical about a first predefined axis, said shape causing said first inductor to have a reduced far field, at least in some directions; and

forming a second inductor on said semiconductor die at a predetermined distance from said first inductor, wherein a mutual electromagnetic coupling between said first inductor and said second inductor is reduced as a result of said first inductor having a reduced far field.

12. The method according to claim 11, wherein said second inductor has a shape that is substantially identical to said shape of said first inductor.

13. The method according to claim 11, further comprising orienting said first inductor and said second inductor in a same direction.

14. The method according to claim 11, further comprising orienting said first inductor and said second inductor in different directions.

15. The method according to claim 11, further comprising placing said first inductor and said second inductor on a common axis that is shared by said first inductor and said second inductor.

16. The method according to claim 11, further comprising placing said first inductor and said second inductor so that they share no common axis.

17. The method according to claim 11, wherein said steps of forming said first and second inductors include forming said first and second inductors in a substantially 8 shape.

18. The method according to claim 17, further comprising forming an inner loop within each outer loop of said substantially 8-shaped first and second inductors.

19. The method according to claim 11, wherein said steps of forming said first and second inductors include forming said first and second inductors in a substantially four-leaf clover shape.

20. The method according to claim 11, wherein said first inductor and said second inductor are symmetrical about a second predefined axis.

21. An inductor having a reduced far field, comprising:

a first loop having a shape that is substantially symmetrical about a first predefined axis; and

a second loop having a size and shape substantially identical to a size and shape of said first loop, said second loop arranged such that a magnetic field emanating therefrom tends to cancel a magnetic field emanating from said first loop.

22. The inductor according to claim 21, wherein said first loop and said second loop are substantially symmetrical about a second predefined axis.

23. The inductor according to claim 21, further comprising:

a third loop in said inductor having a size and shape substantially identical to said size and shape of said first loop, said third loop arranged such that a magnetic field emanating therefrom tends to cancel a magnetic field emanating from said first loop; and

a fourth loop in said inductor having a size and shape substantially identical to a size and shape of said second loop, said fourth loop arranged such that a magnetic field emanating therefrom tends to cancel a magnetic field emanating from said second loop.

24. The inductor according to claim 23, wherein said third loop is inside said first loop and said fourth loop is inside said second loop.