MICRO-ELECTRO-MECHANICAL-SYSTEM (MEMS) DRIVER

• US 20130271228A1
• Filed: 04/11/2013
• Published: 10/17/2013
• Est. Priority Date: 04/12/2012
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Fairchild Semiconductor Corporation (ON Semiconductor Corporation)
• Inventors: Tao, Hai, Opris, Ion
• Granted Patent: US 9,094,027 B2
• Time in Patent Office: Days
• US Class Current: 331/18
• CPC Class Codes: G01C 19/5656 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719
• CPC Class Codes: H03B 5/30 with frequency-determining element being electromechanical resonator
• CPC Class Codes: H03H 2009/02283 Vibrating means
• CPC Class Codes: H03L 7/183 a time difference being used for locking the loop, the counter counting between fixed numbers or the frequency divider dividing by a fixed number H03L7/1806 takes precedence

Abstract

In an example, a driver for a micro-electro-mechanical-system (MEMS) device can include a first input configured to receive a first command signal including an oscillatory command signal, a second input configured to receive a second command signal including a bias command signal, and an amplifier configured to receive a high voltage supply, to provide, to the MEMS device, a closed-loop output signal responsive to both the first command signal and the second command signal in a first state, and to provide an open loop output signal configured to substantially span a voltage range of the high voltage supply in a second state.

Claims

1. A driver for a micro-electro-mechanical-system (MEMS) device, the driver comprising:

a first input configured to receive a first command signal including an oscillatory command signal;

a second input configured to receive a second command signal including a bias command signal; and

an amplifier configured to receive a high voltage supply, the amplifier configured to provide, to the MEMS device, a closed-loop output signal responsive to both the first command signal and the second command signal in a first state, and to provide an open loop output signal configured to substantially span a voltage range of the high voltage supply in a second state.

2. The driver of claim 1, including a first feedback path electrically connected to an output of the amplifier, wherein the feedback path includes a feedback switch responsive to state of a start-up signal, wherein the amplifier provides the open loop output signal when the start-up signal is in a start-up state.

3. The driver of claim 2, wherein the amplifier provides a closed-loop output signal that is modulated by the first command signal and the second command signal when the start-up signal is in a non-start-up state.

4. The driver of claim 1, including a first gain block electrically connected to the first input and a second gain block electrically connected to the second input, wherein gain provided to the first command signal by the first gain block is independent of gain provided to the second command signal by the second gain block.

5. The driver of claim 1, including a first feedback path electrically connected to a first output of the amplifier and a second feedback path electrically connected to a second output of the amplifier, wherein the amplifier is configured to provide, to the MEMS device, a differential closed-loop output signal responsive to both the first command signal and the second command signal in the first state, and to provide a differential open loop output signal that substantially spans the voltage range of the high voltage supply in the second state.

6. The driver of claim 5, wherein the first input is a differential first input configured to receive a first differential command signal including a differential oscillatory command signal.

7. The driver of claim 6, including a first gain block electrically connected to the differential first input and a second gain block electrically connected to the second input, wherein gain provided to the first differential command signal by the first gain block is independent of gain provided to the second command signal by the second gain block.

8. The driver of claim 6, including a first summing junction and a second summing junction electrically connected to the first differential input and configured to sum the first differential command signal and the second command signal.

9. The driver of claim 1, wherein the amplifier includes a plurality of high side current sources and a plurality of low side current sources, wherein the high side current sources are fabricated to sustain a higher voltage than the low side current sources.

10. A method comprising:

generating a first command signal that includes an oscillatory command signal;

generating a second command signal that includes a bias command signal;

providing, at an output of the driver when the driver is in a first state, a closed-loop output signal responsive to both the first command signal and the second command signal; and

providing, at the output of the driver when the driver is in a second state, an open loop output signal configured to substantially span a voltage range of a high voltage supply of the driver.

11. The method of claim 10, including feeding back an output of the driver via a feedback switch, wherein the feedback switch is responsive to a state of a start-up signal, wherein the driver provides the open loop output signal when the start-up signal is in a start-up state.

12. The method of claim 11, wherein the driver provides a closed-loop output signal that is modulated by the first command signal and the second command signal when the start-up signal is in a non-start-up state.

13. The method of claim 10, including providing gain to the first command signal that is independent of gain provided to the second command signal.

14. The method of claim 10, including:

feeding back a first output of the driver via a first feedback switch and feeding back a second output of the driver via a second feedback switch, wherein the first and second feedback switches are responsive to a state of a start-up signal;

providing, to the MEMS device, a differential closed-loop output signal responsive to the both the first command signal and the second command signal in the first state; and

providing a differential open loop output signal that substantially spans the voltage range of the high voltage supply in the second state.

15. The method of claim 14, wherein generating a first command signal includes applying, to a differential first input of the driver, a differential first command signal that includes a differential oscillatory command signal, and wherein the method further includes summing the differential first command signal and the second command signal.

16. The method of claim 15, including providing gain to the differential first command signal that is independent of gain provided to the second command signal.

17. The method of claim 10, including electrically connecting the driver to the MEMS device.

18. A system comprising:

a MEMS device; and

a driver configured to provide an output signal to the MEMS device, wherein the driver includes;

a first input configured to receive a first command signal including an oscillatory command signal;

a second input configured to receive a second command signal including a bias command signal; and

an amplifier configured to receive a high voltage supply, the amplifier configured to provide, to the MEMS device, a closed-loop output signal responsive to both the first command signal and the second command signal in a first state, and to provide an open loop output signal configured to substantially span a voltage range of the high voltage supply in a second state.

19. The system of claim 18, wherein the MEMS device includes a MEMS gyroscope sensor.

20. The system of claim 18, including a first feedback path electrically connected to an output of the amplifier, wherein the feedback path includes a feedback switch responsive to state of a start-up signal, wherein the amplifier provides the open loop output signal when the start-up signal is in a start-up state.

21. The system of claim 20, wherein the amplifier provides a closed-loop output signal that is modulated by the first command signal and the second command signal when the start-up signal is in a non-start-up state.

22. The system of claim 18, including a first gain block electrically connected to the first input and a second gain block electrically connected to the second input, wherein gain provided to the first command signal by the first gain block is independent of gain provided to the second command signal by the second gain block.

23. The system of claim 18, including a first feedback path electrically connected to a first output of the amplifier and a second feedback path electrically connected to a second output of the amplifier, wherein the amplifier is configured to provide, to the MEMS device, a differential closed-loop output signal responsive to the both the first command signal and the second command signal in the first state, and to provide a differential open loop output signal that substantially spans the voltage range of the high voltage supply in the second state.

24. The system of claim 23, wherein the first input is a differential first input configured to receive a first differential command signal including a differential oscillatory command signal.

25. The system of claim 24, including a first gain block electrically connected to the differential first input and a second gain block electrically connected to the second input, wherein gain provided to the first differential command signal by the first gain block is independent of gain provided to the second command signal by the second gain block.

26. The system of claim 18, including a component separate from the MEMS device and the driver, wherein the separate component is configured to provide a startup signal waveform to the first input of the driver.