Lumped cross-coupled Wilkinson circuit

• US 8,130,057 B2
• Filed: 04/30/2009
• Issued: 03/06/2012
• Est. Priority Date: 04/30/2008
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: RF Micro Devices Incorporated (Qorvo, Inc.)
• Inventors: Jones, David E., Hoheisel, Kevin M.
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): GLENN, KIMBERLY E
• Application Number:
  US12/433,377
• Publication Number:
  US 20110063045A1
• Time in Patent Office: 1,041 Days
• Field of Search: 333126-129, 333/131, 333/132, 333/134
• US Class Current: 333/131
• CPC Class Codes: H03H 7/09 Filters comprising mutual inductance
• CPC Class Codes: H03H 7/48 Networks for connecting several sources or loads, working on the same frequency or frequency band, to a common load or source phase shifters providing two or more output signals H03H7/21

Abstract

The present invention relates to a lumped cross-coupled Wilkinson circuit having a pair of magnetically cross-coupled inductive elements coupled to an isolation network. By magnetically cross-coupling the inductive elements, which have a mutual inductance, the inductance of each inductive element will be significantly less than the inductance of each inductive element in an equivalent lumped traditional Wilkinson combiner. Since the inductance of each inductive element is less, the size of each inductive element may be significantly smaller and the resistive loss of the each inductive element may be significantly smaller. In one embodiment of the present invention, the lumped cross-coupled Wilkinson circuit operates as a lumped cross-coupled Wilkinson combiner. In an alternate embodiment of the present invention, the lumped cross-coupled Wilkinson circuit operates as a lumped cross-coupled Wilkinson splitter.

Claims

1. A lumped cross-coupled Wilkinson circuit comprising:

a pair of magnetically coupled inductive elements having a mutual inductance and comprising;

a first inductive element coupled between a common port and a first port and having a first inductance; and

a second inductive element coupled between the common port and a second port, magnetically cross-coupled to the first inductive element, and having a second inductance, such that the first inductive element and the second inductive element are aligned to have reinforcing mutually coupled magnetic flux, wherein a magnitude of the first inductance is about equal to a magnitude of the second inductance; and

an isolation network coupled between the first port and the second port.

2. The lumped cross-coupled Wilkinson circuit of claim 1 further comprising an impedance matching network coupled between the common port and a reference.

3. The lumped cross-coupled Wilkinson circuit of claim 2 wherein:

a coupling factor is associated with the first inductive element and the second inductive element and is about equal to a magnitude of the mutual inductance divided by the magnitude of the first inductance.

4. The lumped cross-coupled Wilkinson circuit of claim 3 wherein the coupling factor is greater than about 0.4.

5. The lumped cross-coupled Wilkinson circuit of claim 2 wherein:

the first port is adapted to receive a first alternating current (AC) signal;

the second port is adapted to receive a second AC signal; and

the common port is adapted to provide a combined AC signal based on combining the first AC signal and the second AC signal,

wherein the lumped cross-coupled Wilkinson circuit operates as a lumped cross-coupled Wilkinson combiner.

6. The lumped cross-coupled Wilkinson circuit of claim 5 wherein:

the first AC signal is based on an in-phase radio frequency (RF) signal;

the second AC signal is based on a quadrature-phase RF signal, which is nominally phase-shifted from the in-phase RF signal by about 90 degrees;

at least one of the in-phase RF signal and the quadrature-phase RF signal are phase-shifted to provide an approximately phase-aligned in-phase RF signal and quadrature-phase RF signal; and

the combined AC signal is a combined RF signal based on combining the approximately phase-aligned in-phase RF signal and quadrature-phase RF signal.

7. The lumped cross-coupled Wilkinson circuit of claim 6 wherein:

the in-phase RF signal is provided by an in-phase RF power amplifier;

the quadrature-phase RF signal is provided by a quadrature-phase RF power amplifier; and

the combined RF signal is an RF transmit signal.

8. The lumped cross-coupled Wilkinson circuit of claim 2 wherein:

the common port is adapted to receive a common alternating current (AC) signal;

the first port is adapted to provide a first AC signal based on splitting the common AC signal; and

the second port is adapted to provide a second AC signal based on splitting the common AC signal,

wherein the lumped cross-coupled Wilkinson circuit operates as a lumped cross-coupled Wilkinson splitter.

9. The lumped cross-coupled Wilkinson circuit of claim 8 wherein:

the common AC signal is a common RF signal;

an in-phase radio frequency (RF) signal is based on the first AC signal;

a quadrature-phase RF signal is based on the second AC signal;

at least one of the first AC signal and the second AC signal are phase-shifted to provide the in-phase RF signal and the quadrature-phase RF signal, such that the quadrature-phase RF signal is phase-shifted from the in-phase RF signal by approximately 90 degrees.

10. The lumped cross-coupled Wilkinson circuit of claim 2 wherein:

the lumped cross-coupled Wilkinson circuit presents a common impedance to the common port;

the lumped cross-coupled Wilkinson circuit presents a first impedance to the first port; and

the lumped cross-coupled Wilkinson circuit presents a second impedance to the second port.

11. The lumped cross-coupled Wilkinson circuit of claim 10 wherein:

when a common external impedance having a magnitude about equal to a magnitude of the common impedance is presented to the common port;

when a first external impedance having a magnitude about equal to a magnitude of the first impedance is presented to the first port; and

when a second external impedance having a magnitude about equal to a magnitude of the second impedance is presented to the second port, then the first port is about isolated from the second port.

12. The lumped cross-coupled Wilkinson circuit of claim 10 wherein:

a coupling factor is about equal to a magnitude of the mutual inductance divided by the magnitude of the first inductance; and

a magnitude of the first impendence is about equal to a magnitude of the second impendence at an isolation frequency.

13. The lumped cross-coupled Wilkinson circuit of claim 12 wherein the magnitude of the first inductance is approximately defined by the following equation:

14. The lumped cross-coupled Wilkinson circuit of claim 12 wherein the impedance matching network comprises an impedance matching capacitive element coupled between the common port and the reference.

15. The lumped cross-coupled Wilkinson circuit of claim 14 wherein the impedance matching capacitive element has an impedance matching capacitance and a magnitude of the impedance matching capacitance is approximately defined by the following equation:

16. The lumped cross-coupled Wilkinson circuit of claim 12 wherein the isolation network comprises an isolation capacitive element and an isolation resistive element coupled in series between the first port and the second port.

17. The lumped cross-coupled Wilkinson circuit of claim 16 wherein the isolation capacitive element has an isolation capacitance and the isolation resistive element has an isolation resistance, such that a magnitude of the isolation capacitance and a magnitude of the isolation resistance are approximately defined by the following equations:

18. The lumped cross-coupled Wilkinson circuit of claim 2 wherein the isolation network is further coupled to the reference.

19. The lumped cross-coupled Wilkinson circuit of claim 2 wherein the reference is about ground.

20. The lumped cross-coupled Wilkinson circuit of claim 2 wherein the impedance matching network comprises an impedance matching capacitive element coupled between the common port and the reference.

21. A lumped cross-coupled Wilkinson circuit comprising:

a pair of magnetically coupled inductive elements having a mutual inductance and comprising;

a first inductive element coupled between a common port and a first port and having a first inductance; and

a second inductive element coupled between the common port and a second port, magnetically cross-coupled to the first inductive element, and having a second inductance, such that the first inductive element and the second inductive element are aligned to have reinforcing mutually coupled magnetic flux;

an isolation network coupled between the first port and the second port; and

an impedance network coupled between the common port and a reference, wherein the isolation network is further coupled to the reference.

22. A lumped cross-coupled Wilkinson circuit comprising:

a pair of magnetically coupled inductive elements having a mutual inductance and comprising;

a first inductive element coupled between a common port and a first port and having a first inductance; and

a second inductive element coupled between the common port and a second port, magnetically cross-coupled to the first inductive element, and having a second inductance, such that the first inductive element and the second inductive element are aligned to have reinforcing mutually coupled magnetic flux;

an isolation network coupled between the first port and the second port; and

wherein;

the first port is adapted to receive a first alternating current (AC) signal;

the second port is adapted to receive a second AC signal; and

the common port is adapted to provide a combined AC signal based on combining the first AC signal and the second AC signal,

wherein the lumped cross-coupled Wilkinson circuit operates as a lumped cross-coupled Wilkinson combiner.