DIRECTIONAL COUPLER AND RF CIRCUIT MODULE

• US 20080070519A1
• Filed: 07/26/2007
• Published: 03/20/2008
• Est. Priority Date: 09/20/2006
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: Renesas Technology Corporation (Renesas Electronics Corporation)
• Inventors: Okabe, Hiroshi
• Granted Patent: US 8,249,544 B2
• Time in Patent Office: Days
• US Class Current: 455/127.1
• CPC Class Codes: H01P 5/184 the guides being strip lines or microstrips

Abstract

A directional coupler with a high coupling per unit area and small variations in characteristic at manufacturing capable of achieving a high directivity easily and an RF circuit module provided with the directional coupler are achieved. A main-line is provided on a front surface of a multi-layer substrate, a ground plane is provided on a back surface of the multi-layer substrate. On an inner layer immediately under the main-line, two lines in parallel with the main-line are provided, and one line is provided on a layer closer to the ground plane than the two lines. By connecting the two lines and the one line with vias, a sub-line with a shape of a winding of a loop is formed. In the sub-line, a main component of a vector vertically penetrating the loop is horizontal with respect to the ground plane.

Claims

1. A directional coupler comprising:

a main-line;

a sub-line; and

a ground plane,

wherein the main-line and/or the sub-line form at least one winding of a loop, and the loop is disposed so that a main component of a vector vertically penetrating the loop is horizontal with respect to the ground plane.

2. The directional coupler according to claim 1,

wherein a first section in which the main-line and/or the sub-line run in parallel in a direction of the same electric current flowing in the main-line and/or the sub-line in maximum times in the loop is disposed at a position farther from the ground plane than a second section other than the first section, and a portion of the main-line and a portion of the sub-line contributing to a coupling between the main-line and the sub-line are disposed at a position farther from the ground plane than the first section or at a position in approximately equal distance from the ground plane to the first section.

3. The directional coupler according to claim 2,

wherein the portion of the main-line contributing to the coupling is disposed at a position farther from the ground plane than the portion of the sub-line contributing to the coupling, so that the portion of the main-line contributing the coupling overlaps the portion of the sub-line contributing the coupling.

4. The directional coupler according to claim 3,

wherein a difference is provided between an entire width of the portion of the main-line contributing to the coupling and an entire width of the portion of the sub-line contributing to the coupling.

5. The directional coupler according to claim 1,

wherein n lines are provided in parallel with the main-line between the main-line and the ground plane (n is an integer equal to or greater than 2), (n−

1) lines are provided between the n lines and the ground plane, and the n lines and the (n−

1) lines are connected so that directions of currents flowing in the n lines are equal to each other to form the sub-line.

6. The directional coupler according to claim 1,

wherein m lines are provided at a position farther from the ground plane than the sub-line and in parallel with the sub-line (m is an integer equal to or greater than 2), (m−

1) lines are provided between the sub-line and the ground plane, and the m lines and the (m−

1) lines are connected so that directions of currents flowing in the m lines are equal to each other to form the main-line.

7. The directional coupler according to claim 1,

wherein the main-line and the sub-line are formed over or inside the same multi-layer substrate, and the ground plane is disposed over or inside a motherboard having the multi-layer substrate mounted thereon.

8. A directional coupler comprising:

a main-line;

a sub-line; and

a ground plane,

wherein n lines facing the ground plane and arranged in parallel are provided (n is an integer equal to or greater than

     2), m lines are provided in parallel with the n lines at a position farther from the ground plane than the n lines (m is an integer equal to or greater than

     2), (n−

1) lines and (m−

1) lines are provided between the n lines and the ground plane, the n lines and the (n−

1) lines are connected so that directions of currents flowing in the n lines are equal to each other to form the sub-line, and the m lines and the (m−

1) lines are connected so that directions of currents flowing in the m lines are equal to each other to form the main-line.

9. The directional coupler according to claim 8,

wherein the main-line and the sub-line are formed over or inside the same multi-layer substrate, and the ground plane is disposed over or inside a primary substrate having the multi-layer substrate mounted thereon.

10. An RF circuit module comprising:

a module substrate formed of a ground plane and a plurality of wiring layers;

a power amplifier mounted on the module substrate amplifying an input transmission signal and outputting transmission signal power;

a directional coupler formed in the plurality of wiring layers of the module substrate including a main-line to which the transmission signal power is input and a sub-line in electromagnetic coupling with the main-line; and

a control unit mounted over the module substrate detecting a signal extracted from the sub-line and adjusting a gain of the power amplifier according to a magnitude of the detected signal,

wherein the main-line and/or the sub-line form at least one winding loop, and the loop is disposed so that a main component of a vector vertically penetrating the loop is horizontal with respect to the ground plane.

11. The RF circuit module according to claim 10,

wherein n lines are provided in parallel with the main-line between the main-line and the ground plane (n is an integer equal to or greater than 2), (n−

1) lines are provided between the n lines and the ground plane, and the n lines and the (n−

1) lines are connected so that directions of currents flowing in the n lines are equal to each other to form the sub-line.

12. The RF circuit module according to claim 10,

wherein m lines are provided in parallel with the sub-line at a position farther from the ground plane than the sub-line (m is an integer equal to or greater than 2), (m−

1) lines are provided between the sub-line and the ground plane, and the m lines and the (m−

1) lines are connected so that directions of currents flowing in the m lines are equal to each other to form the main-line.