Decoupling loop for reducing undesired magnetic coupling between inductors, and related methods and devices

Patent metadata

Field	Value
Publication number	US-9912307-B2
Application number	US-201615074121-A
Country	US
Kind code	B2
Filing date	Mar 18, 2016
Priority date	Mar 19, 2015
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

Devices and related methods use a decoupling loop near closely spaced inductors that couples to each inductor and adds an additional coupling path between them, canceling the effects of the direct coupling between the inductors. When two inductors are close enough that undesired magnetic coupling between the inductors is possible, a decoupling loop adjacent the inductors is added that is configured to cancel the undesired magnetic coupling between the inductors. The decoupling loop is positioned, with respect to the first and second inductors, such that coupling between the decoupling loop and the first inductor induces a decoupling loop current around the decoupling loop and induces a second induced current on the second inductor that is equal and in an opposite direction to a first induced current on the second inductor caused by the first inductor. The undesired magnetic coupling between the conductors is reduced, and may even be totally cancelled.

First claim

What is claimed is:

1. A device having reduced magnetic coupling between inductors comprising:
a first inductor having a first inductance;
a second inductor having a second inductance, wherein there is an undesired magnetic coupling between the first inductor and the second inductor; and
a decoupling loop adjacent the first and second inductors, the decoupling loop configured to cancel the undesired magnetic coupling between the first and second inductors, wherein:
the first inductor is positioned near the second inductor such that a current on the first inductor induces a first induced current on the second inductor; and
the decoupling loop is positioned with respect to the first and second inductors such that coupling between the decoupling loop and the first inductor induces a decoupling loop current around the decoupling loop and induces a second induced current on the second inductor that is equal and in an opposite direction to the first induced current on the second inductor.

2. The device of claim 1 , wherein the decoupling loop is a self-contained current loop.

3. The device of claim 1 , wherein the decoupling loop is not physically attached to either the first inductor or the second inductor.

4. The device of claim 1 , wherein the decoupling loop is not grounded.

5. The device of claim 1 , wherein the first inductor and the second inductor are disposed on a first layer of the device, and the decoupling loop is adjacent one or both of the first inductor and the second inductor and disposed on the first layer.

6. The device of claim 1 , wherein the first and second inductors are disposed on a first layer of the device and the decoupling loop is on a different layer of the device than the first layer.

7. The device of claim 6 , wherein the decoupling loop is routed directly below at least one of the first and second inductors.

8. The device of claim 1 , further comprising a plurality of decoupling loops, wherein the plurality of decoupling loops are configured to cancel the undesired magnetic coupling between the first and second inductors.

9. The device of claim 8 , wherein each of a first decoupling loop and a second decoupling loop of the plurality of decoupling loops is positioned with respect to the first and second inductors such that coupling between the first decoupling loop and the first inductor and coupling between the second decoupling loop and the first inductor each induces a decoupling loop current around the respective one of the first and second decoupling loops and jointly induces a second induced current on the second inductor that is equal and in an opposite direction to the first induced current on the second inductor.

10. The device of claim 8 , wherein the first and second inductors are disposed on a first layer of the device, and each of the plurality of decoupling loops is on a different layer of the device than the first layer.

11. The device of claim 10 , wherein a first one of the plurality of decoupling loops is on a different layer than a second one of the plurality of decoupling loops.

12. The device of claim 10 , wherein at least one of the plurality of decoupling loops is routed on more than one layer.

13. The device of claim 1 , wherein the first and second inductors are printed inductors.

14. The device of claim 1 , wherein the first and second inductors are surface mounted inductors.

15. A power amplifier die having two differential power amplifiers:
a first transformer;
a second transformer positioned side by side to the first transformer, wherein there is an undesired magnetic coupling between the first transformer and second transformer; and
a decoupling loop adjacent the first and second transformers, the decoupling loop configured to cancel the undesired magnetic coupling between the first and second transformers wherein:
the first transformer is positioned near the second transformer such that a current on the first transformer induces a first induced current on the second transformer; and
the decoupling loop is positioned with respect to the first and second transformers such that coupling between the decoupling loop and the first transformer induces a decoupling loop current around the decoupling loop and induces a second induced current on the second transformer that is equal and in an opposite direction to the first induced current on the second transformer.

16. A method of reducing undesired magnetic coupling comprising:
disposing a first inductor having a first inductance on a first layer of a device;
disposing a second inductor having a second inductance on the first layer, wherein the second inductor is near enough the first inductor that an undesired magnetic coupling is possible between the first inductor and second inductor; and
placing a decoupling loop adjacent the first and second inductors, wherein the decoupling loop is configured to cancel the undesired magnetic coupling between the first and second inductors, wherein:
disposing the second inductor on the first layer further comprises disposing the second inductor near enough the first inductor that a current on the first inductor induces a first induced current on the second inductor; and
placing the decoupling loop adjacent the first and second inductors further comprises placing the decoupling loop with respect to the first and second inductors such that coupling between the decoupling loop and the first inductor induces a decoupling loop current around the decoupling loop and induces a second induced current on the second inductor that is equal and in an opposite direction to the first induced current on the second inductor.

17. The method of claim 16 , wherein placing the decoupling loop adjacent the first and second inductors further comprises placing the decoupling loop on a different layer of the device than the first layer.

18. The power amplifier die of claim 15 , wherein the first and second transformers are disposed on a first layer of the power amplifier die and the decoupling loop is on a different layer of the power amplifier die than the first layer.

19. The power amplifier die of claim 18 , wherein the decoupling loop is routed directly below at least one of the first and second transformers.

20. The method of claim 17 , wherein placing the decoupling loop on a different layer of the device than the first layer further comprises placing the decoupling loop directly below at least one of the first and second inductors.

Assignees

• Rf Micro Devices Inc
• Qorvo Us Inc

Inventors

• Lewis Timothy D

Classifications

• H01F27/38

  Auxiliary core members; Auxiliary coils or windings · CPC title

• H03F2200/537

  A transformer being used as coupling element between two amplifying stages · CPC title

• H01F27/289

  with auxiliary windings (for pancake coils H01F27/2871) · CPC title

• H01F17/0006

  Printed inductances (printed coils for dynamo-electric machines H02K3/26; printed circuits H05K) · CPC title

• H01F27/2804

  Printed windings · CPC title