Multimode oscillator enabling simultaneous monitoring of variations in several resonance frequencies of a resonator

Patent metadata

Field	Value
Publication number	US-9515608-B2
Application number	US-201514976767-A
Country	US
Kind code	B2
Filing date	Dec 21, 2015
Priority date	Dec 22, 2014
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

A multimode oscillator comprising:
a resonator including:
a moving element; actuators of the moving element according to two symmetric and antisymmetric resonance modes; several detectors of the displacement of the moving element;
polarization circuitry of the detectors by signals out of phase with each other; a first calculator carrying out a first operation conserving the frequential components of the first mode and cancelling those of the second mode; a second calculator carrying out a second operation conserving the frequential components of the second mode and cancelling those of the first mode;

and in which the resonator and the calculators form two self-oscillating loops making the oscillator resonate simultaneously in the two modes.

First claim

The invention claimed is:

1. A multimode oscillator comprising at least:
a resonator including:
at least one moving element
actuators able to make the moving element resonate according to at least two resonance modes of which one is symmetric and the other is antisymmetric;
several detectors of the displacement of the moving element each comprising at least one electrical parameter of which the value varies as a function of the displacement of the moving element and coupled to the moving element such that they induce, in at least first and second output signals of the resonator representative of the variations in said electrical parameter, phase differences such that φ E1 −φ O1 ≠φ E2 −φ O2 , with φ E1 the phase of a first frequential component of the first output signal linked to a first of the resonance modes, φ O1 the phase of a first frequential component of the second output signal linked to the first of the resonance modes, φ E2 the phase of a second frequential component of the first output signal linked to a second of the resonance modes, and φ O2 the phase of a second frequential component of the second output signal linked to the second of the resonance modes;

polarization circuitry able to apply to the detectors electric polarization signals;
a first calculator able to carry out at least one first operation between the first and second output signals conserving the first frequential components of the first and second output signals and cancelling the second frequential components of the first and second output signals;
a second calculator able to carry out at least one second operation between the first and second output signals conserving the second frequential components of the first and second output signals and cancelling the first frequential components of the first and second output signals;
and in which the resonator and the first and second calculators form part of at least two self-oscillating loops able to make the resonator resonate simultaneously in the two resonance modes.

2. The multimode oscillator according to claim 1 , in which the moving element comprises a beam of which the two ends are built-in.

3. The multimode oscillator according to claim 1 , in which the polarization circuitry is such that the electric polarization signals are continuous and of different values, or alternating and out of phase with respect to each other.

4. The multimode oscillator according to claim 3 , in which the first operation is an addition and the second operation is a subtraction.

5. The multimode oscillator according to claim 1 , in which the actuators comprise an electrode able to apply to the moving element an electrostatic force making the moving element resonate according to the two resonance modes, or comprise at least two electrodes each able to apply to the moving element an electrostatic force favouring making the moving element resonate according to one of the two resonance modes.

6. The multimode oscillator according to claim 1 , in which each detector comprises a piezoresistive strain gauge.

7. The multimode oscillator according to claim 6 , in which:
two first detectors form a first piezoresistive strain gauge bridge;
two second detectors form a second piezoresistive strain gauge bridge; and
the polarization circuitry is able to apply the electric polarization signals to the terminals of each of the first and second piezoresistive strain gauge bridges.

8. The multimode oscillator according to claim 1 , in which each of the two self-oscillating loops comprises at least one amplifier and one first phase shifter.

9. The multimode oscillator according to claim 8 , in which the polarization circuitry comprises at least:
two generators of third and fourth alternating signals of different frequencies;
two second phase shifters each comprising an input connected to an output of one of the two generators and able to apply a same phase shift to the third and fourth alternating signals;
a first adder able to receive at input the fourth alternating signal not phase shifted and the third alternating signal phase shifted by one of the second phase shifters, and a second adder able to receive at input the third alternating signal not phase shifted and the fourth alternating signal phase shifted by the other of the second phase shifters, the signals intended to be outputted by the first and second adders corresponding to the electric polarization signals which are alternating and phase shifted with respect to each other.

10. The multimode oscillator according to claim 9 , in which the first phase shifters each comprise an input connected to an output of one of the two generators and able to apply a different phase shift to each of the third and fourth alternating signals, and further comprising, in each of the two self-oscillating loops, a mixer of which a first input is connected to an output of one of the first and second calculators and of which a second input is connected to an output of one of the first phase shifters.

11. The multimode oscillator according to claim 1 , further comprising frequency measurement devices able to measure the frequencies of the first and second output signals.

12. A detection device comprising a plurality of multimode oscillators according to claim 1 , in which the resonators of the multimode oscillators form a detection array.

13. The detection device according to claim 12 , in which the polarization circuitry is common to all of the multimode oscillators and is arranged beside the detection array, and/or in which at least a part of the elements of the self-oscillating loops of the multimode oscillators other than the resonators are arranged under the detection array.

14. The detection device according to claim 12 , in which groups of resonators form macro-pixels of the detection array, and at least a part of the elements of the self-oscillating loops of the multimode oscillators of each macro-pixel other than the resonators and/or the polarization circuitry are common to all of the multimode oscillators of said macro-pixel.

15. The detection device according to claim 12 , comprising multimode oscillators each further comprising frequency measurement devices able to measure the frequencies of the first and second output signals, and in which said detector is a mass spectrometer and further comprises a calculator of a mass of particles and a position of deposition of the mass of particles on each resonator of the multimode oscillators from frequency measurements of the first and second output signals of each resonator.

Assignees

• Commissariat Energie Atomique

Inventors

• Gourlat Guillaume
• Billiot Gerard
• Villard Patrick

Classifications

• H03B5/323 Primary

  the resonator having more than two terminals (H03B5/326 takes precedence) · CPC title

• H03B25/00

  Simultaneous generation by a free-running oscillator of oscillations having different frequencies · CPC title

• H03B5/30 Primary

  with frequency-determining element being electromechanical resonator · CPC title