Laminated balun transformer

• US 6,768,410 B1
• Filed: 06/11/2003
• Issued: 07/27/2004
• Est. Priority Date: 04/19/2001
• Status: Expired due to Term

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Yazaki, Hirokazu, Toujo, Atsushi
• Primary Examiner(s): Mai, Anh
• Application Number:
  US10/311,752
• Time in Patent Office: 412 Days
• Field of Search: 336/200, 336/223, 336/232
• US Class Current: 336/200
• CPC Class Codes: H01F 17/0013 with stacked layers
• CPC Class Codes: H01F 2017/008 Electric or magnetic shielding of printed inductances
• CPC Class Codes: H01F 27/2804 Printed windings
• CPC Class Codes: H01P 5/10 for coupling balanced lines or devices with unbalanced lines or devices
• CPC Class Codes: H03H 7/422 comprising distributed impedance elements together with lumped impedance elements

Abstract

A laminated balun transformer includes first line elements which are connected in series through a relay terminal, to constitute an unbalanced transmission line. Other line elements each constitute a balanced transmission lines. Strip lines are electromagnetically coupled to constitute a coupler. Similarly, other line elements are electromagnetically coupled to constitute a coupler. A ground terminal is connected to the balanced transmission lines, which are constituted by a pair of the line elements. Meanwhile, a shield terminal is connected to leading portions of shield electrodes. These two terminals are electrically independent of each other.

Claims

1. A laminated balun transformer comprising:

a stack in which, at least a pair of balanced transmission lines, an unbalanced transmission line that is electromagnetically coupled with the pair of balanced transmission lines, a shield electrode that opposes at least one of the balanced transmission lines and the unbalanced transmission line, and a plurality of dielectric layers are stacked;

a ground terminal that is provided on a surface of the stack and that is electrically connected to the balanced transmission lines; and

a shield terminal that is provided on a surface of the stack and that is electrically connected to the shield electrode;

wherein the ground terminal and the shield terminal are electrically independent of each other.

2. The laminated balun transformer according to claim 1, wherein the stack includes a plurality of dielectric sheets having lead electrodes and line elements disposed thereon.

3. The laminated balun transformer according to claim 2, wherein each of the line elements has an electrical length corresponding to a ¼

wavelength.

4. The laminated balun transformer according to claim 2, wherein shield electrodes are provided on the plurality of dielectric sheets.

5. The laminated balun transformer according to claim 2, wherein the lead electrodes have a spiral configuration.

6. The laminated balun transformer according to claim 2, wherein each of the lead electrodes are electrically connected to another of the lead electrodes through via holes formed in the stack.

7. A laminated balun transformer comprising:

a pair of balanced transmission lines;

an unbalanced transmission line that is electromagnetically coupled with the pair of balanced transmission lines;

an unbalanced signal terminal that is electrically connected to one end of the unbalanced transmission line;

two balanced signal terminals, each of the two balanced signal terminals being electrically connected to one end of a corresponding one of the pair of balanced transmission lines;

a common bias terminal that is electrically connected to the other ends of the pair of balanced transmission lines; and

a bias capacitor that is electrically connected between the common bias terminal and ground.

8. The laminated balun transformer according to claim 7, further comprising a stack including the pair of balanced transmission lines, the unbalanced transmission line, and a shield electrode that opposes at least one of the pair of balanced transmission lines and the unbalanced transmission line.

9. The laminated balun transformer according to claim 8, wherein the stack includes a plurality of dielectric sheets having lead electrodes and line elements disposed thereon.

10. The laminated balun transformer according to claim 9, wherein each of the line elements has an electrical length corresponding to a ¼

wavelength.

11. The laminated balun transformer according to claim 10, wherein shield electrodes are provided on the plurality of dielectric sheets.

12. The laminated balun transformer according to claim 10, wherein the lead electrodes have a spiral configuration.

13. The laminated balun transformer according to claim 10, wherein each of the lead electrodes are electrically connected to another of the lead electrodes through via holes formed in the stack.

14. The laminated balun transformer according to claim 8, wherein the common bias terminal and the shield electrode are electrically independent of each other.

15. The laminated balun transformer according to claim 8, further comprising a ground terminal that is provided on a surface of the stack and electrically connected to the pair of balanced transmission lines, wherein the ground terminal and the shield terminal are electrically independent of each other.

16. A laminated balun transformer comprising:

a stack in which, at least a pair of balanced transmission lines, an unbalanced transmission line that is electromagnetically coupled with the pair of balanced transmission lines, a shield electrode that opposes at least one of the pair of balanced transmission lines and the unbalanced transmission line, a pair of bias-capacitor patterns, and a plurality of dielectric layers are stacked;

a common bias terminal that is provided on a surface of the stack and that is electrically connected to the balanced transmission lines and one of the pair of bias-capacitor patterns; and

a shield terminal that is provided on a surface of the stack and that is electrically connected to the shield electrode and the other of the pair of bias-capacitor patterns;

wherein the common bias terminal and the shield terminal are electrically independent of each other.

17. The laminated balun transformer according to claim 16, wherein the stack includes a plurality of dielectric sheets having lead electrodes and line elements disposed thereon.

18. The laminated balun transformer according to claim 17, wherein each of the line elements has an electrical length corresponding to a ¼

wavelength.

19. The laminated balun transformer according to claim 17, wherein shield electrodes are provided on the plurality of dielectric sheets.

20. The laminated balun transformer according to claim 17, wherein the lead electrodes have a spiral configuration.

21. The laminated balun transformer according to claim 17, wherein each of the lead electrodes are electrically connected to another of the lead electrodes through via holes formed in the stack.