System comprising a mechanical resonator and method therefor

Patent metadata

Field	Value
Publication number	US-9644965-B2
Application number	US-201514642202-A
Country	US
Kind code	B2
Filing date	Mar 9, 2015
Priority date	Oct 9, 2014
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

A system comprises a mechanical resonator; an analog circuit operably coupled to the mechanical resonator; the analog circuit arranged to receive a mechanical resonator measurement signal and to output a mechanical resonator actuation signal to the mechanical resonator; and a digital actuator operably coupled to the analog circuit and configured to provide a frequency sweep of signals to the analog circuit that induces movement of the mechanical resonator.

First claim

The invention claimed is:

1. A system comprising:
a mechanical resonator;
an analog circuit operably coupled to the mechanical resonator; the analog circuit arranged to receive a mechanical resonator measurement signal and to output a mechanical resonator actuation signal to the mechanical resonator; and
a digital actuator operably coupled to the analog circuit and configured to provide a frequency sweep of signals to the analog circuit that induces movement of the mechanical resonator,
wherein the digital actuator starts the frequency sweep of signals provided to the analog circuit at a frequency higher or lower than a resonant frequency of the mechanical resonator and sweeps the frequency towards and beyond said resonant frequency.

2. The system of claim 1 , wherein the digital actuator is configured to provide the frequency sweep of signals to the analog circuit around a natural frequency of the mechanical resonator.

3. The system of claim 1 , wherein the frequency sweep of signals provided to the analog circuit comprises a stream of digital pulses close to the resonant frequency of the mechanical resonator.

4. The system of claim 1 , wherein the frequency sweep of signals provided to the analog circuit provides a kick start to the mechanical resonator from an idle state.

5. The system of claim 1 , wherein the frequency sweep of signals provided to the analog circuit provides a digital kick start of the mechanical resonator.

6. The system of claim 1 , wherein the digital actuator is arranged to generate a frequency sweep of signals at least initially in an open loop manner.

7. The system of claim 6 , wherein the digital actuator comprises an accumulator arranged to accumulate a frequency step size of digital pulses in generating the frequency sweep of signals.

8. The system of claim 7 , wherein the frequency step size is configurable.

9. The system of claim 8 wherein the frequency step size is configured to be zero when the digital actuator determines that the mechanical resonator measurement signal input to the analog circuit is close to the natural frequency of the mechanical resonator.

10. The system of claim 7 wherein the digital actuator comprises a kick clock period counter operably coupled to the accumulator and arranged to limit a number of digital pulses generated in the open loop manner.

11. The system of claim 6 , wherein a continued frequency sweep of signals is generated in a closed loop manner.

12. The system of claim 11 , wherein the digital actuator further comprises a clock period counter arranged to receive and measure a duration of a mechanical resonator clock signal output by the analog circuit.

13. The system of claim 7 , wherein the digital actuator further comprises a phase and frequency detector operably coupled to a clock period counter and a kick clock period counter operably coupled to the accumulator and arranged to compare a frequency and phase output of the clock period counter and the kick clock period counter.

14. The system of claim 13 , wherein the digital actuator further comprises a phase and frequency modulator operably coupled to the phase and frequency detector and arranged to perform at least one from a group of:
update the frequency step size;
update a sign associated with the frequency step size;
stop the frequency sweep when the frequency and phase output of the clock period counter and the kick clock period counter match.

15. The system of claim 14 wherein the frequency step size is an integer number of a digital master clock period and a fractional number of the mechanical resonator frequency.

16. The system of claim 1 wherein the system comprises a micro-electro-mechanical system device.

17. The system of claim 16 wherein the system is a vibrating gyroscope and the mechanical resonator is a proof-mass.

18. An integrated circuit comprising at least one die within a single integrated circuit package, wherein the integrated circuit comprises the digital actuator according to claim 1 .

19. A method of generating an actuation signal for a mechanical resonator within an micro-electro-mechanical system (MEMS) device, the method comprising:
turning on the MEMS device;
receiving a mechanical resonator measurement signal at an analog circuit operably coupled to the mechanical resonator;
outputting a mechanical resonator actuation signal to the mechanical resonator with the analog circuit;
providing a frequency sweep of signals to the analog circuit to act as a kick start actuation signal for the MEMS device in response to the turn on, the frequency sweep of signals provided by a digital actuator operably coupled to the analog circuit, wherein the frequency sweep of signals starts at a frequency higher or lower than a natural frequency of the mechanical resonator and sweeps towards and beyond said natural frequency; and
inducing movement of the mechanical resonator with the analog circuit in response to the frequency sweep of signals.

Assignees

• Beaulaton Hugues
• Cassagnes Thierry
• Cornibert Laurent
• Wahl Volker
• Nxp Usa Inc

Inventors

• Beaulaton Hugues
• Cassagnes Thierry
• Cornibert Laurent
• Wahl Volker

Classifications

• G01C19/5776 Primary

  Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719 · CPC title

• G01C19/5726

  Signal processing · CPC title

• H03B2200/0094

  Measures to ensure starting of oscillations · CPC title