MEMS controlled oscillator

• US 20070200648A1
• Filed: 11/09/2006
• Published: 08/30/2007
• Est. Priority Date: 11/09/2005
• Status: Active Grant

• Current Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Original Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Inventors: Aubin, Keith, Zalalutdinov, Maxim, Craighead, Harold, Parpia, Jeevak, Reichenbach, Robert
• Granted Patent: US 7,843,283 B2
• Time in Patent Office: Days
• US Class Current: 333/133
• CPC Class Codes: G01S 7/032 Constructional details for solid-state radar subsystems
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H03H 3/0072 of microelectro-mechanical resonators or networks micromembranes or microbeams B81B2203/01; manufacture of microstructural devices in general B81C
• CPC Class Codes: H03H 9/02401 by annealing
• CPC Class Codes: H03H 9/2436 Disk resonators

Abstract

An array of micromechanical oscillators have different resonant frequencies based on their geometries. In one embodiment, a micromechanical oscillator has a resonant frequency defined by an effective spring constant that is modified by application of heat. In one embodiment, the oscillator is disc of material supported by a pillar of much smaller diameter than the disc. The periphery of the disc is heated to modify the resonant frequency (or equivalently the spring constant or stiffness) of the disc. Continuous control of the output phase and frequency may be achieved when the oscillator becomes synchronized with an imposed sinusoidal force of close frequency. The oscillator frequency can be detuned to produce an easily controlled phase differential between the injected signal and the oscillator feedback. A phased array radar may be produced using independent phase controllable oscillators.

Claims

1. A device comprising:

an array of microelectromechanical resonators having a variety of resonant frequencies, each resonator having an actuator that causes the resonator to resonate at their resonant frequency; and

an antenna coupled to the array.

2. The device of claim 1 wherein the resonators are selected from the group consisting of a disc supported by a pillar, a cantilevered beam and a bridge.

3. The device of claim 1 wherein each resonator includes a disc supported by a pillar, and wherein the resonators have different diameter discs to provide the variety of resonant frequencies.

4. The device of claim 1 wherein each resonator includes a disc supported by a pillar, and wherein the resonators have different size pillars to provide the variety of resonant frequencies.

5. The device of claim 1 wherein each resonator includes a disc supported by a pillar, and wherein the resonators have different thicknesses to provide the variety of resonant frequencies.

6. The device of claim 1 wherein the resonators include resistive heaters.

7. The device of claim 1 and further comprising lasers for selectively heating the resonators.

8. The device of claim 1 wherein the resonators include a feedback loop to achieve a stable resonance frequency.

9. The device of claim 1 and further comprising means to detect or cause resonance.

10. The device of claim 1 and further comprising an amplifier coupled to the resonators.

11. The device of claim 1 wherein each resonator is independently actuatable and detectable.

12. The device of claim 1 wherein the resonators have a range of resonant frequencies as a function of differences in geometry of the resonators.

13. The device of claim 12 wherein a length of the resonators is varied to provide the range of resonant frequencies.

14. A device comprising:

an array of microelectromechanical resonators having different resonant frequencies within a desired range of frequencies;

a resistive heater coupled to each resonator to cause the resonators to resonate; and

an antenna coupled to the resonators.

15. The device of claim 14 wherein the resonators all have different resonant frequencies.

16. The device of claim 14 wherein the range of frequencies is within the RF range of frequencies.

17. The device of claim 14 wherein the resonators are independently actuated via the resistive heaters.

18. The device of claim 14 wherein the resonators are actuated in unison via the resistive heaters.

19. The device of claim 14 wherein the resistive heaters are adapted to provide localized heating of the resonators.

20. The device of claim 14 wherein each resonator includes a detector that detects the frequency at which the resonator is oscillating.

21. The device of claim 20 wherein the detector is piezo-resistive, capacitive and/or optical based.

22. A device comprising:

an array of microelectromechanical resonators having different resonant frequencies within a desired range of frequencies;

an actuator associated with each resonator to cause the resonators to resonate; and

a detector associated with each resonator to detect the frequency of resonation of the associated resonators.

23. The device of claim 22 and further comprising an antenna coupled to the resonators.

24. A method of producing an array of resonators having different resonant frequencies within a desired range of frequencies, the method comprising:

patterning a variety of resonator geometries calculated to provide the desired range of resonant frequencies; and

etching to release the resonators.