Microelectromechanical device having an oscillating mass and a forcing stage, and method of controlling a microelectromechanical device

Patent metadata

Field	Value
Publication number	US-2016109237-A1
Application number	US-201514985071-A
Country	US
Kind code	A1
Filing date	Dec 30, 2015
Priority date	Mar 13, 2013
Publication date	Apr 21, 2016
Grant date	—

Abstract

A microelectromechanical device includes: a body; a movable mass, elastically coupled to the body and oscillatable with respect to the body according to a degree of freedom; a frequency detector, configured to detect a current oscillation frequency of the movable mass; and a forcing stage, capacitively coupled to the movable mass and configured to provide energy to the movable mass through forcing signals having a forcing frequency equal to the current oscillation frequency detected by the frequency detector, at least in a first transient operating condition.

First claim

1 . A method of controlling a microelectromechanical device, comprising:
oscillating a movable mass with respect to a body according to a degree of freedom, the movable mass being elastically coupled to the body; detecting a current oscillation frequency of the movable mass using a frequency detector; and providing energy to the movable mass by a forcing stage, capacitively coupled to the movable mass, through forcing signals having a forcing frequency equal to the current oscillation frequency detected by the frequency detector, at least in a first transient operating condition.

2 . The method of claim 1 further comprising detecting a current oscillation phase of the movable mass, wherein providing energy comprises providing the forcing signals with a constant phase delay with respect to the detected current oscillation phase.

3 . The method of claim 2 , wherein the constant phase delay is less than π/2.

4 . The method of claim 3 , wherein the constant phase delay is zero.

5 . The method according to claim 1 further comprising maintaining the microelectromechanical loop in oscillation at a driving frequency in a steady operating condition using a driving device coupled to the movable mass so as to form a microelectromechanical loop.

6 . The method of claim 5 , wherein detecting the current oscillation frequency of the movable mass comprises providing a main clock signal synchronous with oscillations of the microelectromechanical loop in the first transient operating condition, and the forcing signals are generated on the basis of the main clock signal in the first transient operating condition.

7 . The method of claim 1 , wherein detecting the current oscillation frequency of the movable mass comprises using a PLL circuit.

8 . The method of claim 1 further comprising providing a reference clock signal, independent of oscillations of the movable mass; wherein providing energy to the movable mass through forcing signals comprises generating the forcing signals on the basis of the reference clock signal in a second transient operating condition.

9 . The method of claim 8 , wherein the forcing signals include a maximum number of cycles in the second transient operating condition, the maximum number of cycles selected so that a phase delay of the forcing signals with respect to oscillations of the movable mass does not exceed π/2.

10 . The method of claim 1 further comprising terminating supply of the forcing signals based on a comparison between a current oscillation amplitude of the movable mass and a threshold oscillation amplitude.

11 . The method of claim 1 , wherein the forcing signals comprise sequences of square-wave pulses.

12 . A method of controlling a microelectromechanical device, comprising:
oscillating a movable mass with respect to a body according to a degree of freedom; detecting a current oscillation frequency of the movable mass; and providing energy to the movable mass through forcing signals having a forcing frequency equal to the detected current oscillation frequency in a first transient operating condition.

13 . The method of claim 12 , comprising detecting a current oscillation phase of the movable mass, wherein providing energy comprises providing the forcing signals with a constant phase delay with respect to the detected current oscillation phase.

14 . The method of claim 13 , wherein the constant phase delay is less than π/2.

15 . The method of claim 14 , wherein the constant phase delay is zero.

16 . The method of claim 12 , comprising maintaining the microelectromechanical loop in oscillation at a driving frequency in a steady operating condition using a driving device coupled to the movable mass so as to form a microelectromechanical loop.

17 . The method of claim 16 , wherein detecting a current oscillation frequency of the movable mass comprises:
providing a main clock signal synchronous with oscillations of the microelectromechanical loop in the first transient operating condition; and generating the forcing signals on the basis of the main clock signal in the first transient operating condition.

18 . The method of claim 17 further comprising locking the forcing signals and oscillations of the microelectromechanical loop in the first transient operating condition.

19 . A method of controlling a microelectromechanical device, comprising:
oscillating a movable mass with respect to a body according to a degree of freedom; detecting a current oscillation frequency of the movable mass; providing energy to the movable mass through forcing signals having a forcing frequency equal to the detected current oscillation frequency in a first transient operating condition; providing a reference clock signal independent of oscillations of the movable mass; and generating the forcing signals on the basis of the reference clock signal in a second transient operating condition.

20 . The method of claim 19 , wherein the forcing signals include a maximum number of cycles in the second transient operating condition, the maximum number of cycles selected so that a phase delay of the forcing signals with respect to oscillations of the movable mass does not exceed π/2.

Assignees

• St Microelectronics Srl

Inventors

• Garbarino Marco
• Donadel Andrea
• Magnoni Davide
• Valzasina Carlo

Classifications

• G01C19/5726

  Signal processing · CPC title

• G01C19/5762 Primary

  the sensing mass being connected to a driving mass, e.g. driving frames · CPC title