Zeroeth-order resonator

• US 20060066422A1
• Filed: 03/28/2005
• Published: 03/30/2006
• Est. Priority Date: 03/26/2004
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Itoh, Tatsuo, Sanada, Atsushi, Caloz, Christophe
• Granted Patent: US 7,330,090 B2
• Time in Patent Office: Days
• US Class Current: 333/219
• CPC Class Codes: H01P 7/082 Microstripline resonators H01P7/088 takes precedence

Abstract

A high frequency resonator circuit and method of fabrication is described which has a resonant frequency independent of physical resonator dimensions. The resonator operates in a zeroeth-order mode on a composite right/left-handed (CRLH) transmission line (TL). The LH wave properties of the CRLH-TL contributing anti-parallel phase and group velocities. In one variation, the unit cells are formed from microstrip techniques, preferably creating alternating interdigitated capacitors and stub inductors. The resonant wavelength of the resonator is dependent on the electrical characteristics of the unit cells and not the physical size of the resonator in relation to the desired resonant wavelength. The resonator is created with at least 1.5 unit cells and the Q of the resonator is substantially independent of the number of unit cells utilized. The resonator circuit is particularly well suited for reducing resonator size, and allows resonators of various wavelengths to be fabricated within a fixed board area.

Claims

1. A resonator apparatus, comprising:

a composite high frequency right/left-handed (CRLH) transmission line (TL);

means for combining unit cells having a desired equivalent shunt inductance and shunt capacitance within said CRLH-TL; and

at least one input and output port on said resonator for coupling high frequency signals into and out of said resonator;

wherein said TL is configured for resonating at the zeroeth-order characterized by an infinite-wavelength wave in the CRLH-TL and has a resonant frequency which is independent of the physical size characteristics of the resonator.

2. A resonator as recited in claim 1:

wherein said high frequency CRLH-TL is configured to operate at a frequency of at least approximately 100 MHz; and

wherein at least about an order of magnitude less power is dissipated by the series resistance of said resonator apparatus than with a conventional resonator for the same frequency range.

3. A resonator as recited in claim 1, wherein said LH-TL is configured for providing anti-parallel phase and group velocities.

4. A resonator as recited in claim 1, wherein said means for combining unit cells having a desired equivalent shunt inductance and shunt capacitance comprises:

a plurality of passive components in each unit cell;

wherein said passive components include at least one interdigitated capacitor operably coupled to at least one stub inductor; and

wherein said passive components from adjacent unit cells are operable coupled to one another within the CRLH-TL, and to said input and output ports.

5. A resonator as recited in claim 4, wherein each said unit cell comprises an interdigitated capacitor and a stub inductor.

6. A resonator apparatus, comprising:

a composite high frequency right/left-handed (CRLH) transmission line (TL);

wherein said LH-TL is configured for providing anti-parallel phase and group velocities;

at least 1.5 unit cells having inductors and capacitors formed as microstrips providing a desired equivalent shunt inductance and shunt capacitance within said CRLH-TL;

at least one input and output port on said resonator for coupling high frequency signals into and out of said resonator; and

wherein said TL is configured for resonating at the zeroeth-order characterized by an infinite-wavelength wave in the CRLH-TL and has a resonant frequency which is independent of the physical size characteristics of the resonator.

7. A resonator as recited in claim 6, wherein said capacitors comprise interdigitated capacitors.

8. A resonator as recited in claim 7, wherein a capacitive comb attached to a first inductor is positioned in a desired relation with a capacitive comb coupled to a second inductor therein coupling unit cells within said CRLH-TL.

9. A resonator as recited in claim 8, wherein a unit cell comprises a single interdigitated capacitor, formed from two capacitive combs, and coupled to an inductor positioned in a desired relation with said interdigitated capacitor.

10. A resonator as recited in claim 6, wherein said inductors comprises inductive traces, or studs.

11. A resonator as recited in claim 6:

wherein said high frequency of TL is at a frequency within, near, or above the gigahertz range; and

wherein at least an order of magnitude less power is dissipated by the series resistance of said resonator apparatus than with a conventional resonator for the same frequency range.

12. A resonator as recited in claim 6, wherein said resonator is a microwave resonator for use in high frequency communication systems, circuit devices, filters, and oscillators.

13. A resonator as recited in claim 6, wherein said at least one input and output port on said resonator comprise conductive input and output trace regions separated from said CRLH-TL by a desired gap distance.

14. A resonator as recited in claim 6, wherein said CRLH-TL may comprise a plurality of unit cells whose number is determined by the desired accuracy of resonator response.

15. A resonator as recited in claim 6, wherein said resonator of N unit cells has a resonant frequency ω

following that of the LC tank circuit which has an inductance of L_L/N and a capacitance of NC_R, as given by;

$\mathrm{\omega <br><br>}=\frac{1}{\sqrt{\left(L_L/N\right)·<br><br>{\mathrm{NC}}_R}}=\frac{1}{\sqrt{L_L<br><br>C_R}}={\mathrm{\omega <br><br>}}_{\mathrm{sh}}.$

16. A resonator as recited in claim 6, wherein the unloaded Q of the resonator is substantially independent of the number of unit cells.

17. A resonator as recited in claim 6, wherein said resonator can be created to provide an unloaded Q of at least 250.

18. A method of implementing high frequency resonators, comprising:

forming an inductor-capacitor (LC) unit cell configured to include left-hand wave operation for contributing anti-parallel phase and group velocities;

coupling at least 1.5 unit cells into a composite right/left-handed (CRLH) transmission line (TL) configured for resonating at the zeroeth-order characterized by an infinite-wavelength wave in the CRLH-TL with a resonant frequency which is independent of the physical size characteristics of the resonator; and

coupling at least one input port and output port to said CRLH-TL.

19. A method as recited in claim 18, wherein said unit cell is formed comprising coupling at least one interdigitated capacitor to at least one stub inductor.

20. A method as recited in claim 18, wherein said input and output ports are capacitively coupled to said CRLH-TL.