Measuring system having electromechanical resonators, method for manufacturing such a system, and method for reading at least two electromechanical resonators

• US 9,470,576 B2
• Filed: 03/29/2012
• Issued: 10/18/2016
• Est. Priority Date: 03/31/2011
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Original Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Inventors: Colinet, Eric, Andreucci, Philippe, Duraffourg, Laurent, Hentz, Sbastien
• Primary Examiner(s): Saint Surin, J M
• Application Number:
  US14/009,044
• Publication Number:
  US 20140013848A1
• Time in Patent Office: 1,664 Days
• Field of Search: 735/79
• US Class Current: 1/1
• CPC Class Codes: G01D 5/02 using mechanical means
• CPC Class Codes: G01D 5/14 influencing the magnitude of a current or voltage
• CPC Class Codes: G01H 13/00 Measuring resonant frequency

Abstract

A measuring system including: at least two electromechanical resonators each having a resonant frequency varying around an offload resonant frequency according to a physical quantity to be measured; at least one reading device connected to inputs of the resonators and configured to supply an excitation signal on the inputs; and a memory in which is recorded, for each resonator, offload resonance information relating to the offload resonant frequency of the resonator. Each reading device is configured to determine the resonant frequency of one or more resonators selected for reading by configuring at least one element of the reading device using the offload resonance information stored for each selected resonator.

Claims

1. A measuring system, comprising:

at least two electromechanical resonators, each having a resonant frequency varying around an offload resonant frequency according to a physical quantity to be measured, each resonator including;

an input configured to receive an excitation signal,

an output configured to supply an output signal in response to the excitation signal, the output signal having resonance at the resonant frequency of the resonator, and

a mechanical structure defining the offload resonant frequency, the mechanical structures of the resonators being different from one another so that the offload resonant frequencies are different from one another, all inputs of the resonators being connected together to receive a same excitation signal;

an adding device for adding the output signals as a total output signal,

a memory in which is recorded, for each resonator, offload resonance information relating to the offload resonant frequency of the resonator,

a reading device configured to determine the resonant frequency of one resonator selected for reading,

wherein the reading device is configured to receive the total output signal,

wherein the reading device includes a closed-loop configured to supply an excitation signal to the resonators according to the total output signal,

wherein, for determining the resonant frequency of the selected resonator, the reading device is configured to configure, before reading, at least one element of the closed-loop from the offload resonance information stored for the selected resonator, and

wherein, for determining the resonant frequency of the selected resonator, the closed-loop with the configured element is configured to attach, after a time, to the resonant frequency of the selected resonator.

2. The system according to claim 1, comprising plural reading devices configured to simultaneously determine the resonant frequencies of selected resonators.

3. The system according to claim 2, further comprising an adding device to add the excitation signals supplied by the reading devices to supply a total excitation signal at the inputs of the electromechanical resonators.

4. The system according to claim 2, wherein each reading device is configured to determine, from the total output signal, the resonant frequency of a single selected resonator.

5. The system according to claim 1, wherein, for each electromechanical resonator, the input and the output are different.

6. The system according to claim 1, wherein each reading device is configured to successively determine, from the total output signal, the resonant frequency of plural selected resonators.

7. The system according to claim 1, wherein the adding device comprises a node to which the outputs of the resonators are connected.

8. The system according to claim 1, wherein, for each resonator, the offload resonance information is a bandwidth extending around the offload resonant frequency, wherein the reading device comprises at least one auto-oscillation loop comprising a demultiplexer configured to extract, from the total output signal, each of the output signals of the resonators selected for reading, the extraction being performed, for each resonator selected for reading, in the bandwidth particular to the resonator selected for reading.

9. The system according to claim 1, wherein the offload resonance information particular to each resonator is the offload resonant frequency of the particular resonator.

10. The system according to claim 9, wherein the reading device is configured to determine the resonant frequency of a single resonator, and select the offload resonant frequency of the resonator selected for reading, and is configured to supply, at a start of reading, a single-frequency excitation signal with a frequency equal to the selected offload resonant frequency.

11. The system according to claim 9, wherein the reading device comprises a controlled phase loop circuit configured to fix, after starting the reading, the frequency of the excitation signal on the frequency of a resonance peak of the total signal corresponding to the resonator selected for reading and to supply the fixed frequency as the determined resonant frequency.

12. The system according to claim 11, wherein the controlled phase loop circuit is configured to start the fixing at the selected offload resonant frequency.

13. The system according to claim 1, wherein the electromechanical resonators are MEMS resonators or NEMS resonators.

14. The system according to claim 13, wherein the electromechanical resonators are NEMS resonators etched on a same silicon chip.

18. The system according to claim 1,

wherein the reading device includes several closed-loops, each closed-loop being configured to supply an excitation signal to the inputs of the resonators according to the total output signal,

wherein the reading device is configured to determine resonant frequencies of resonators selected for reading, by configuring, before reading, at least one element of each closed-loop from the offload resonance information stored for a respective selected resonator, and

wherein each closed-loop with the configured element is configured to attach, after a time, to the resonant frequency of the respective selected resonator.

19. The system according to claim 1, wherein the reading device is configured to determine, for each selected resonator, the physical quantity from the resonant frequency determined and the offload resonant frequency of the resonator.

15. A method for sizing electromechanical resonators, the method comprising:

determining, for each resonator, an expected maximum variation range of its resonant frequency around its offload resonant frequency; and

choosing mechanical structures that define offload resonant frequencies of the resonators in a manner such that the offload resonant frequencies are substantially separate from one another in order for the determined ranges to be non-overlapping.

16. A method for reading at least two electromechanical resonators each comprising a mechanical structure defining an offload resonant frequency, the mechanical structures of the resonators being different from one another so that the offload resonant frequencies are different from one another, and each having a resonant frequency varying around the offload resonant frequency according to a physical quantity to be measured, each resonator including an input configured to receive an excitation signal and an output configured to supply, in response to the excitation signal, an output signal, the output signal having a resonance at the resonant frequency of the electromechanical resonator, all inputs of the resonators being connected together to receive a same excitation signal and the output signals being added as a total output signal by an adding device, the method using a reading device comprising a memory

in which is recorded, for each resonator, offload resonance information relating to the offload resonant frequency of the resonator and a closed-loop configured to receive the total output signal and supply an excitation signal to the resonators according to the total output signal, the method comprising:

selecting, from the resonators, one resonator to be read;

recovering from the memory, the offload resonance information of the selected resonator;

applying an excitation signal to the resonators using the closed-loop;

determining the resonant frequency of the selected resonator by configuring, before reading, at least one element of the closed-loop from the offload resonance information stored for the selected resonator, such that the closed-loop with the configured element is configured to attach, after a time, to the resonant frequency of the selected resonator; and

determining the physical quantity from the resonant frequency determined and the offload resonant frequency of the resonator.

17. The method according to claim 16, further comprising, before applying the excitation signal to the resonators:

determining the offload resonant frequencies of the resonators;

determining, for each resonator, the offload resonance information from its offload resonant frequency; and

recording the offload resonance information in the memory.