Applying a positive feedback voltage to an electromechanical sensor utilizing a voltage-to-voltage converter to facilitate a reduction of charge flow in such sensor representing spring

Patent metadata

Field	Value
Publication number	US-11428702-B2
Application number	US-201916460901-A
Country	US
Kind code	B2
Filing date	Jul 2, 2019
Priority date	Aug 14, 2018
Publication date	Aug 30, 2022
Grant date	Aug 30, 2022

Abstract

Reducing a sensitivity of an electromechanical sensor is presented herein. The electromechanical sensor comprises a sensitivity with respect to a variation of a mechanical-to-electrical gain of a sense element of the electromechanical sensor; and a voltage-to-voltage converter component that minimizes the sensitivity by coupling, via a defined feedback capacitance, a positive feedback voltage to a sense electrode of the sense element—the sense element electrically coupled to an input of the voltage-to-voltage converter component. In one example, the voltage-to-voltage converter component minimizes the sensitivity by maintaining, via the defined feedback capacitance, a constant charge at the sense electrode. In another example, the electromechanical sensor comprises a capacitive sense element comprising a first node comprising the sense electrode. Further, a bias voltage component can apply a bias voltage to a second node of the electromechanical sensor. In yet another example, the electromechanical sensor comprises a piezoelectric sense element.

First claim

What is claimed is:

1. A system, comprising:
an electromechanical sensor comprising
a sense element comprising a first node comprising a sense electrode,
a bias voltage component that applies a bias voltage to a second node, different than the first node, of the sense element, and
a sensitivity with respect to a variation of a mechanical-to-electrical gain of the sense element, wherein the sense element comprises a capacitive sense element or a piezoelectric sense element; and

a voltage-to-voltage converter component that generates, via an output of the voltage-to-voltage converter component, a positive feedback voltage, wherein the voltage-to-voltage converter component minimizes the sensitivity by coupling, via a defined feedback capacitance, the positive feedback voltage to the sense electrode, wherein the sense electrode is electrically coupled to an input of the voltage-to-voltage converter component wherein the voltage-to-voltage converter component comprises a defined input capacitance, a defined amplifier feedback capacitance, an inverting amplifier comprising a defined negative gain represented by a ratio of the defined input capacitance to the defined amplifier feedback capacitance, and a unity-gain inverting voltage buffer comprising, within a defined error tolerance, a gain of negative one, wherein an output of the inverting amplifier is electrically coupled to an input of the unity-gain inverting voltage buffer, wherein an output of the unity-gain inverting voltage buffer is electrically coupled to the output of the voltage-to-voltage converter component, wherein the defined input capacitance is electrically coupled to an input of the inverting amplifier, and wherein the defined amplifier feedback capacitance is electrically coupled between the input of the inverting amplifier and the output of the inverting amplifier.

2. The system of claim 1 , wherein the voltage-to-voltage converter component minimizes the sensitivity by maintaining, via the defined feedback capacitance, a constant charge at the sense electrode.

3. The system of claim 1 , further comprising a defined parasitic capacitance that is electrically coupled to the input of the voltage-to-voltage converter component.

4. The system of claim 3 , wherein a value of the defined feedback capacitance is proportional, based on the defined negative gain of the inverting amplifier, to the defined parasitic capacitance.

5. The system of claim 1 , wherein the input of the inverting amplifier is coupled, via a coupling capacitance, to a defined self-test voltage that facilitates generation of a force on a proof mass of the electromechanical sensor.

6. A system, comprising:
a micro-electro-mechanical system (MEMS) sensor comprising a sensitivity with respect to a change of a mechanical-to-electrical gain of a sense element of the MEMS sensor; and
a voltage-to-voltage converter component comprising a differential amplifier, wherein the voltage-to-voltage converter component minimizes the sensitivity with respect to the change of the mechanical-to-electrical gain of the sense element by coupling, via respective defined feedback capacitances, a positive differential feedback voltage to respective sense electrodes of the sense element, wherein the respective sense electrodes are electrically coupled to respective inputs of the voltage-to-voltage converter component, and wherein respective defined input capacitances of the system are electrically coupled between the respective sense electrodes of the sense element and respective differential inputs of the differential amplifier.

7. The system of claim 6 , wherein respective defined amplifier feedback capacitances are electrically coupled between the respective differential inputs of the differential amplifier and respective outputs of the differential amplifier, and wherein the respective defined feedback capacitances are electrically coupled between the respective outputs of the differential amplifier and the respective sense electrodes of the sense element.

8. A system, comprising:
an electromechanical sensor comprising a sensitivity with respect to a variation of a mechanical-to-electrical gain of a sense element of the electromechanical sensor; and
a voltage-to-voltage converter component that
generates, via an output of the voltage-to-voltage converter component, a positive feedback voltage, and
minimizes the sensitivity by coupling, via a defined feedback capacitance, the positive feedback voltage to a sense electrode of the sense element, wherein the sense electrode is electrically coupled to an input of the voltage-to-voltage converter component, wherein the voltage-to-voltage converter component further comprises a defined input capacitance, a defined amplifier feedback capacitance, an inverting amplifier comprising a defined negative gain represented by a ratio of the defined input capacitance to the defined amplifier feedback capacitance, and a unity-gain inverting voltage buffer comprising, within a defined error tolerance, a gain of negative one, wherein the output of the inverting amplifier is electrically connected to an input of the unity-gain inverting voltage buffer, wherein an output of the unity-gain inverting voltage buffer is electrically connected to the output of the voltage-to-voltage converter component, wherein the defined input capacitance is electrically coupled between the input of the voltage-to-voltage converter component and an input of the inverting amplifier, and wherein the defined amplifier feedback capacitance is electrically coupled between the input of the inverting amplifier and an output of the inverting amplifier.

9. The system of claim 8 , further comprising a defined parasitic capacitance that is electrically connected to the input of the voltage-to-voltage converter component.

10. The system of claim 9 , wherein the defined parasitic capacitance comprises a defined shield capacitance corresponding to at least one electrical trace of the system that facilitates shielding at least a portion of the sense electrode from an electromagnetic field.

11. The system of claim 10 , wherein a value of the defined feedback capacitance is proportional, based on the defined negative gain of the inverting amplifier, to a sum of the defined parasitic capacitance and the defined input capacitance.

12. The system of claim 8 , wherein the input of the inverting amplifier is coupled, via a coupling capacitance, to a defined self-test voltage that facilitates generation of a force on a proof mass of the electromechanical sensor.

13. The system of claim 8 , wherein the input of the inverting amplifier is coupled, via a coupling capacitance, to a defined quadrature cancellation voltage that facilitates a reduction of a value of a quadrature portion of the input of the inverting amplifier.

14. The system of claim 1 , wherein the voltage-voltage converter component further comprises:
a unity-gain voltage buffer electrically connected between the sense electrode and the defined input capacitance, wherein the unity-gain voltage buffer comprises, within a defined error tolerance, a gain of one.

15. The system of claim 14 , wherein an input of the unity-gain voltage buffer is electrically coupled to a first capacitance terminal of a defined shield capacitance of the system, and wherein the output of the unity-gain voltage buffer is electrically coupled to a second capacitance terminal of the defined shield capacitance.

16. A system, comprising:
an electromechanical sensor comprising a sensitivity with respect to a variation of a mechanical-to-electrical gain of a sense element

Assignees

• Invensense Inc

Inventors

• Seeger Joseph
• Shettigar Pradeep

Classifications

• H03F2200/48

  the output of the amplifier being coupled out by a capacitor · CPC title

• H03F2203/45156

  At least one capacitor being added at the input of a dif amp · CPC title

• G01P1/006 Primary

  used for thermal compensation · CPC title

• G01P15/125

  by capacitive pick-up · CPC title

• H03F2203/45546

  the IC comprising one or more capacitors feedback coupled to the IC · CPC title