Miniature dynamically tunable microwave and millimeter wave device

• US 5,175,521 A
• Filed: 05/31/1991
• Issued: 12/29/1992
• Est. Priority Date: 05/31/1991
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Larson, Lawrence E.
• Primary Examiner(s): LaRoche, Eugene R.
• Assistant Examiner(s): Neyzari, Ali
• Application Number:
  US07/708,530
• Time in Patent Office: 578 Days
• Field of Search: 333/235, 333/246, 333/221, 333/205, 333/224, 333/225, 333/231, 333/263, 333/33, 333/35, 333/81 A, 333/105, 333/232, 334/41, 334/45, 334/78, 200/181, 310/309
• US Class Current: 333/235
• CPC Class Codes: H01P 1/20336 Comb or interdigital filters
• CPC Class Codes: H01P 5/04 with variable factor of coupling
• CPC Class Codes: H01P 7/088 Tunable resonators
• CPC Class Codes: H02N 1/004 in which a body is moved along a path due to interaction with an electric field travelling along the path

Abstract

A miniature, electrostatically actuated, variable impedance circuit element which is operably tunable in response to control signals. With integrated circuit, thin film processing a fixed circuit member is fabricated on a substrate and a movable circuit member is fabricated over the substrate and is movable relative to the fixed circuit member in response to electrostatic fields produced at armature tabs when the control signals are selectively applied to rows of control electrodes. Embodiments include a variable capacitor and a variable ring resonator.

Claims

1. A miniature, electrostatically actuated, tunable circuit comprising:

a substrate having a first circuit member disposed at one surface thereof;

a second circuit member disposed above said substrate, said second circuit member being movable relative to said first circuit member; and

control means fabricated on said substrate and being operable to selectively receive control signals for producing electrostatic fields which are coupled to said second circuit member, the electrostatic fields being operable to selectively move said second circuit member relative to said first circuit member and operably tune said tunable circuit.

2. The miniature, electrostatically actuated, tunable circuit of claim 1 in which said control mean is disposed with an air gap that is sufficiently narrow such that the control means will induce an image charge on said second circuit member to enhance electrostatic attraction.

3. The miniature, electrostatically actuated, tunable circuit of claim 1 in which said control means includes a plurality of separate control electrodes distributed on at least one side of said second circuit member.

4. The miniature, electrostatically actuated, tunable circuit of claim 3 in which said separate control electrodes are distributed alongside of said second circuit member and are operable to move said second circuit member linearly to operably tune said turnable circuit.

5. The miniature, electrostatically actuated, tunable circuit of claim 4 in which said first and said second circuit member includes a plurality of spaced apart finger members in which said finger member of said first circuit member interdigitally mate with said finger members of said second circuit member to effect the capacitance of said tunable circuit.

6. The miniature, electrostatically actuated, tunable circuit of claim 5 in which said finger members are parallel to each other and have planar side walls.

7. The miniature, electrostatically actuated, tunable circuit of claim 4 in which said first circuit member includes a first segment of a ring and said second circuit member includes a second segment of a ring that compliments said first segment, said second segment being operable to slide along a surface of said first segment of a ring to form a closed ring which is operable as a ring resonator.

8. The miniature, electrostatically actuated, tunable circuit of claim 7 in which said first and said second segments of a ring have individual linear portions that are in sliding contact with each other.

9. The miniature, electrostatically actuated, tunable circuit of claim 2 in which said second circuit member includes at least one tab projecting from a side wall thereof, said tab being operably electrostatically attracted by the electrostatic fields produced by said control electrodes.

10. The miniature, electrostatically actuated, tunable circuit of claim 1 in which said first and said second circuit members have a rectangular cross section.

11. The miniature, electrostatically actuated, tunable circuit of claim 9 in which said first and said second circuit members have a rectangular cross section.

12. The miniature, electrostatically actuated, tunable circuit of claim 1 in which said first and said second circuit members are fabricated of thin films.

13. The miniature, electrostatically actuated, tunable circuit of claim 1 in which said control means are fabricated of thin films.

14. The miniature, electrostatically actuated, tunable circuit of claim 1 in which said substrate is a material from the group consisting of gallium-arsenide, indium phosphide, and sapphire.

15. The miniature, electrostatically actuated, tunable circuit of claim 1 in which said first and said second circuit members each comprise a layer of gold.

16. The miniature, electrostatically actuated, tunable circuit of claim 1 in which said control means comprises a layer of gold.

17. The miniature, electrostatically actuated, tunable circuit of claim 1 in which said first and said second circuit members and said control means comprise a thin layer of titanium and gold and a thicker layer of gold.

18. A miniature, electrostatically actuated, circuit element comprising:

a substrate having a first circuit element fixed thereto;

a second circuit element having a surface member and which is movable relative to said first circuit element; and

control means including control electrodes each having planar faces that are disposed in parallel planes and which match said surface member with an air gap there between and to allow said second circuit element to move through the region beside said control electrodes and to operably effect electrostatic attraction between said control electrodes and an image charge on said surface member in response to a control signal applied to said control electrode.