Voltage tunable laminated dielectric materials for microwave applications

• US 6,377,142 B1
• Filed: 10/15/1999
• Issued: 04/23/2002
• Est. Priority Date: 10/16/1998
• Status: Expired due to Term

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Paratek Microwave Incorporated (Blackberry Limited)
• Inventors: Zhang, Xubai, Kozyrev, Andrey, Zhu, Yongfei, Sengupta, Somnath, Sengupta, Louise, Chiu, Luna H., Stowell, Steven C.
• Primary Examiner(s): LEE, BENNY T
• Application Number:
  US09/419,047
• Time in Patent Office: 921 Days
• Field of Search: 333/238, 333/246, 333/161, 333/156, 343/754
• US Class Current: 333/238
• CPC Class Codes: H01P 1/181 using ferroelectric devices
• CPC Class Codes: H01P 3/003 Coplanar lines
• CPC Class Codes: H01P 3/06 Coaxial lines
• CPC Class Codes: H01P 3/081 Microstriplines
• CPC Class Codes: H01P 3/088 Stacked transmission lines
• CPC Class Codes: H01P 3/122 Dielectric loaded (not air)
• CPC Class Codes: H01P 7/06 Cavity resonators
• CPC Class Codes: H01Q 3/44 varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
• CPC Class Codes: H05K 1/024 Dielectric details, e.g. changing the dielectric material around a transmission line
• CPC Class Codes: H05K 1/162 incorporating printed capacitors
• CPC Class Codes: H05K 2201/0187 with regions of different dielectrics in the same layer, e.g. in a printed capacitor for locally changing the dielectric properties
• CPC Class Codes: H05K 2201/037 Hollow conductors, i.e. conductors partially or completely surrounding a void, e.g. hollow waveguides
• CPC Class Codes: H05K 2203/105 Using an electrical field; Special methods of applying an electric potential electroplating H05K2203/0723
• CPC Class Codes: H05K 2203/171 Tuning, e.g. by trimming of printed components or high frequency circuits

Abstract

A tunable dielectric structure includes a first layer of dielectric material, a second layer of dielectric material positioned adjacent to the first layer of dielectric material, with the second layer of dielectric material having a dielectric constant that is less than the dielectric constant of the first layer of dielectric material, and electrodes for applying a controllable voltage across the first dielectric material, thereby controlling a dielectric constant of the first dielectric material, wherein at least one of the electrodes is positioned between the first and second layers of dielectric material. The dielectric materials can be formed in various shapes and assembled in various orientations with respect to each other. The tunable dielectric structure is used in various devices including a coaxial cables, cavity antenna, microstrip lines, coplanar lines, and waveguides.

Claims

1. A tunable dielectric structure comprising:

a first layer of dielectric material, having a dielectric constant greater than 100;

a second layer of dielectric material, having a dielectric constant less than 30, positioned adjacent to said first layer of dielectric material;

first and second electrodes for applying a first controllable voltage across said first layer of dielectric material, thereby controlling the dielectric constant of said first layer of dielectric material, wherein one of said first and second electrodes is positioned between said first and second layers of dielectric material; and

means for applying a second controllable voltage across said second layer of dielectric material, thereby controlling the dielectric constant of said second layer of dielectric material.

2. A tunable dielectric structure as recited in claim 1, wherein said first and second layers of said dielectric material each have a respective thickness less than about one tenth of the wavelength of a radio frequency signal to be transmitted through the tunable dielectric structure.

3. A tunable dielectric structure as recited in claim 1, further comprising:

a plurality of additional layers of dielectric material positioned in parallel with said first and second layers of dielectric material, and at least selected ones of said additional layers of dielectric material respectively having a tunable dielectric constant.

4. A tunable dielectric structure as recited in claim 3, wherein said first, second and additional layers of said dielectric material are assembled into a plurality of subassemblies.

5. A tunable dielectric structure as recited in claim 1, wherein said first layer of dielectric material has a loss tangent of less that 0.01.

6. A tunable dielectric structure as recited in claim 1, wherein said second layer of dielectric material comprises a BA₁₋

xSr_xTiO₃ composite where x ranges from zero to one.

7. A tunable dielectric structure as recited in claim 1, wherein said first and second layers of said dielectric material are rectangular slabs lying in planes that are oriented parallel to a direction of propagation of a radio frequency signal through the tunable dielectric structure.

8. A tunable dielectric structure as recited in claim 1, wherein said first and second layers of said dielectric material comprise one of the group of bulk, tape, thick film and thin film layers.

9. A microstrip line comprising:

a first layer of dielectric material;

a second layer of dielectric material positioned adjacent to said first layer of dielectric material, said second layer of dielectric material having a dielectric constant that is less than a dielectric constant of said first layer of dielectric material;

first and second electrodes for applying a first controllable voltage across said first layer of dielectric material, thereby controlling the dielectric constant of said first dielectric material, wherein one of said first and second electrodes is positioned between said first and second layers of dielectric material;

a ground plane positioned adjacent to a first edge of each of said first and second layers; and

a microstrip positioned adjacent to a second edge of each of said first and second layers.

10. A microstrip line as recited in claim 9, further comprising:

a plurality of additional layers of dielectric material positioned in parallel with said first and second layers of dielectric material, and at least selected ones of said additional layers of dielectric material respectively having a tunable dielectric constant.

11. A microstrip line as recited in claim 10, wherein said first, second and additional layers of said dielectric material are assembled into a plurality of subassemblies.

12. A microstrip line as recited in claim 9, wherein said first layer of dielectric material has dielectric constant greater than about 100 and a loss tangent of less than about 0.01.

13. A microstrip line as recited in claim 9, wherein said second layer of dielectric material comprises one of:

a Ba<sub>1−

x</sub>Sr_xTiO₃ composite where x ranges from zero to one, alumina, mica, and air.

14. A microstrip line as recited in claim 9, wherein said first and second layers of said dielectric material comprise one of the group of bulk, tape, thick film and thin film layers.

15. A microstrip line as recited in claim 9, wherein said first and second layers of said dielectric material each have a respective thickness less than about one tenth of the wavelength of a radio frequency signal to be transmitted through the device.

16. A microstrip line as recited in claim 9, further comprising:

means for applying a second controllable voltage across said second dielectric material, thereby controlling the dielectric constant of said second dielectric material.

17. A tunable dielectric structure comprising:

a first layer of dielectric material, having a dielectric constant greater than 100;

a second layer of dielectric material, having a dielectric constant less than 30, positioned adjacent to said first layer of dielectric material;

a third layer of dielectric material, having a dielectric constant greater than 100, positioned adjacent to said second layer of dielectric material;

means for applying a first controllable voltage across said first layer of dielectric material, thereby controlling the dielectric constant of said first layer of dielectric material; and

means for applying a second controllable voltage across said third layer of dielectric material, thereby controlling the dielectric constant of said second layer of dielectric material;

wherein the first, second and third layers of dielectric material each have a thickness of less than one tenth of a wavelength of a signal to be transmitted through the structure.

18. A tunable dielectric structure as recited in claim 17, wherein said first, second and third layers of dielectric material each have a respective thickness less than about one tenth of the wavelength of a radio frequency signal to be transmitted through the tunable dielectric structure.

19. A tunable dielectric structure as recited in claim 17, further comprising:

means for applying a third controllable voltage across said second dielectric material, thereby controlling the dielectric constant of said second dielectric material.