MEMS RESONATOR FOR FILTERING AND MIXING

• US 20110102095A1
• Filed: 06/18/2009
• Published: 05/05/2011
• Est. Priority Date: 06/18/2008
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Van Beek, Jozef T. M., Reimann, Klaus, Steeneken, Peter Gerard
• Granted Patent: US 8,493,157 B2
• Time in Patent Office: Days
• US Class Current: 332/175
• CPC Class Codes: H03D 7/00 Transference of modulation from one carrier to another, e.g. frequency-changing H03D9/00, H03D11/00 take precedence; dielectric amplifiers, magnetic amplifiers, parametric amplifiers used as a frequency-changers H03F
• CPC Class Codes: H03H 2009/02496 Horizontal, i.e. parallel to the substrate plane
• CPC Class Codes: H03H 2009/2442 Square resonators
• CPC Class Codes: H03H 9/02259 Driving or detection means
• CPC Class Codes: H03H 9/02275 Comb electrodes
• CPC Class Codes: H03H 9/2452 Free-free beam resonators
• CPC Class Codes: H03H 9/465 in combination with other electronic elements

Abstract

A method of operating a micro-electromechanical system, comprising a resonator; an actuation electrode; and a first detection electrode, to filter and mix a plurality of signals. The method comprises applying a first alternating voltage signal to the actuation electrode, wherein an actuation force is generated having a frequency bandwidth that is greater than and includes a resonant bandwidth of a mechanical frequency response of the resonator, and wherein a displacement of the resonator is produced which is filtered by the mechanical frequency response and varies a value of an electrical characteristic of the first detection electrode. The method also comprises applying a second alternating voltage signal to the first detection electrode, wherein the second voltage signal is mixed with the varying value to produce a first alternating current signal. The first alternating current signal is detected at the first detection electrode.

Claims

1. A method of operating a micro-electromechanical system having a resonator;

an actuation electrode; and

a first detection electrode, to filter and mix a plurality of signals, the method comprising;

applying a first alternating voltage signal to the actuation electrode, wherein an actuation force is generated having a frequency bandwidth that is greater than and includes a resonant bandwidth of a mechanical frequency response of the resonator, and wherein a displacement of the resonator is produced which is filtered by the mechanical frequency response and varies a value of an electrical characteristic of the first detection electrode;

applying a second alternating voltage signal to the first detection electrode, wherein the second voltage signal is mixed with the varying value to produce a first alternating current signal; and

detecting the first alternating current signal at the first detection electrode.

2. The method of claim 1, further comprising applying a third alternating voltage signal to the actuation electrode, wherein the first voltage signal is mixed with the third voltage signal to generate the actuation force.

3. The method of claim 1, wherein the micro-electromechanical system also includes a second detection electrode, the method further comprising:

applying a fourth voltage signal to the second detection electrode; and

detecting a second alternating current signal at the second detection electrode.

4. The method of claim 3, wherein the fourth voltage signal is an alternating voltage signal, wherein the fourth voltage signal is mixed with a varying value of an electrical characteristic of the second electrode to produce the second alternating current signal.

5. A micro-electromechanical system adapted to filter and mix a plurality of signals, comprising:

a resonator;

an actuation electrode to which a first alternating voltage signal is applied, wherein an actuation force is generated having a frequency bandwidth that is greater than and includes a resonant bandwidth of a mechanical frequency response of the resonator and wherein a displacement of the resonator is produced which is filtered by the mechanical frequency response;

a first detection electrode having an electrical characteristic a value of which is varied by the displacement of the resonator, to which first detection electrode a second alternating voltage signal is applied, wherein the second voltage signal is mixed with the varying value to produce a first alternating current; and

a first current detector that detects the first alternating current signal at the first detection electrode.

6. The system of claim 5, wherein a third alternating voltage signal is applied to the actuation electrode, wherein the first voltage signal is mixed with the third voltage signal to generate the actuation force.

7. The system of claim 5 further comprising a second detection electrode.

8. The system of claim 7, wherein a fourth voltage signal is applied to the second detection electrode;

and further comprising

a second current detector that detects a second alternating current signal at the second detection electrode.

9. The system of claim 8, wherein the fourth voltage signal is an alternating voltage signal, wherein the fourth voltage signal is mixed with a varying value of an electrical characteristic of the second electrode to produce the second alternating current signal.

10. The system of claim 5, wherein the actuation electrode is one of an electrostatic actuator and an electrostrictive actuator.

11. The system of claim 5, wherein the first detection electrode is one of:

a piezoresistive detector, wherein the electrical characteristic is a resistance;

an electrostatic detector, wherein the electrical characteristic is a capacitance; and

an electrostrictive detector wherein the electrical characteristic is a capacitance.

12. The system of claim 10, wherein at least one of the actuation electrode and the first detection electrode is a comb-drive electrostatic electrode.

13. The system of claim 11, wherein one of the first and second detection electrodes is a piezoresistive detector and the other detection electrode is one of an electrostatic detector and an electrostrictive detector.

14. The system of claim 5, wherein the resonator is adapted to resonate in an extensional mode.