Composite right/left (CRLH) couplers

• US 8,405,469 B2
• Filed: 12/06/2011
• Issued: 03/26/2013
• Est. Priority Date: 03/26/2004
• Status: Active Grant

• Current Assignee: California Polytechnic State University (California State University System), Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Itoh, Tatsuo, Caloz, Christophe, Lin, I-Hsiang, Okabe, Hiroshi
• Primary Examiner(s): Takaoka, Dean O
• Application Number:
  US13/312,328
• Publication Number:
  US 20120139659A1
• Time in Patent Office: 476 Days
• Field of Search: 333/109, 333/110, 333/111, 333/112, 333/117, 333/118, 333/120
• US Class Current: 333/118
• CPC Class Codes: H01P 5/227 90° branch line couplers

Abstract

High-frequency couplers and coupling techniques are described utilizing artificial composite right/left-handed transmission line (CRLH-TL). Three specific forms of couplers are described; (1) a coupled-line backward coupler is described with arbitrary tight/loose coupling and broad bandwidth; (2) a compact enhanced-bandwidth hybrid ring coupler is described with increased bandwidth and decreased size; and (3) a dual-band branch-line coupler that is not limited to a harmonic relation between the bands. These variations are preferably implemented in a microstrip fabrication process and may use lumped-element components. The couplers and coupling techniques are directed at increasing the utility while decreasing the size of high-frequency couplers, and are suitable for use with separate coupler or couplers integrated within integrated devices.

Claims

1. A coupling device apparatus, comprising:

a substrate;

a right-handed transmission line disposed on said substrate; and

a left-handed transmission line disposed on said substrate and in communication with said right-handed transmission line, with said left-handed transmission line having a capacitance and an inductance, wherein the capacitance and inductance are selected to yield a −

90 degree phase rotation of an input signal through said left handed transmission.

2. The apparatus recited in claim 1, wherein said left-handed transmission line comprises a metamaterial.

3. The apparatus recited in claim 1, further comprising a second left-handed transmission line and a second right-handed transmission line coupled between said left-handed transmission line and said right-handed transmission line.

4. The apparatus recited in claim 1, wherein said coupling device apparatus accepts an input signal in a microwave frequency range.

5. The apparatus recited in claim 1, wherein the coupling device apparatus is a hybrid ring.

6. The apparatus recited in claim 5, wherein said hybrid ring has a radius less than about 15 mm.

7. The apparatus recited in claim 1, wherein said substrate is less than about 2 mm in thickness.

8. The apparatus recited in claim 1, wherein said left-handed transmission line comprises a metal insulator metal capacitor.

9. The apparatus recited in claim 1, further comprising multiple output lines configured for outputting a signal from the coupling device apparatus.

10. The apparatus recited in claim 1, wherein said left-handed transmission line comprises multiple cells that each contribute a phase shift, with a cumulated phase shift of these multiple cells resulting in said −

90 degree phase shift.

11. A method for implementing a branch line coupler having a first and a second operating frequency, comprising:

selecting a first operating frequency as a selected first operating frequency, and a second operating frequency as a selected second operating frequency;

determining phase delays for a combined right-hand and left-hand transmission line at said selected first operating frequency and said selected second operating frequency;

determining impedance and admittance values as a function of determined phase delays;

determining left-hand inductance and capacitance values based on the admittance values; and

determining electrical length of the right-hand transmission line as a function of said selected first operating frequency and determined impedance, and said selected second operating frequency and determined impedance.

12. The method recited in claim 11, further comprising determining physical length of a microstrip line based on electrical length of the right-hand transmission line.

13. The method recited in claim 11, comprising determining a lumped-distribution-elements corresponding to determined electrical length.

14. The method recited in claim 11, comprising selectively adding a tuning stub based on measured frequency response of the branch line coupler.

15. The method recited in claim 11, wherein said first frequency and said second frequency have an arbitrary frequency relationship that is not constrained to a harmonic relationship or integer multiple value.

16. The method recited in claim 11, wherein the branch line coupler is implemented in a monolithic microwave integrated circuit.

17. The method recited in claim 11, wherein the branch line coupler is implemented in surface mount chips.

18. The method recited in claim 11, wherein said first operating frequency and said second operating frequency are selected to correspond to frequency bands of a dual band wireless device.

19. The method recited in claim 11:

wherein said left-handed transmission line comprises multiple cells that each provide a positive phase shift; and

wherein said right-handed transmission line comprises multiple cells that each provide a negative phase shift.

20. The method recited in claim 19, further comprising interleaving said multiple cells of said right-handed transmission line with said multiple cells of said left-handed transmission line.