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 softening

Patent metadata

Field	Value
Publication number	US-11835538-B2
Application number	US-202217894077-A
Country	US
Kind code	B2
Filing date	Aug 23, 2022
Priority date	Aug 14, 2018
Publication date	Dec 5, 2023
Grant date	Dec 5, 2023

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 microphone, comprising:
an electromechanical sensor comprising
a capacitive sense element comprising a first node and a second node,
a bias voltage component that applies a bias voltage to the first node of the capacitive sense element, and
a sensitivity with respect to a variation of a mechanical-to-electrical gain of the capacitive sense element; and

a voltage-to-voltage converter component that
generates, via a first output, a positive feedback voltage,
generates, via a second output, a negative feedback voltage, and
minimizes the sensitivity by coupling, via a defined feedback capacitance, the positive feedback voltage to the first node of the capacitive sense element, wherein the first node of the capacitive sense element is electrically coupled to an input of the voltage-to-voltage converter component, and wherein the negative feedback voltage is electrically coupled to the second node of the capacitive sense element.

2. The microphone 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 first node of the capacitive sense element.

3. The microphone of claim 1 , wherein the voltage-to-voltage converter component comprises a unity-gain voltage buffer comprising, within a defined error tolerance, a gain of one, and wherein the input of the voltage-to-voltage converter component is electrically connected to an input of the unity-gain voltage buffer.

4. The microphone of claim 3 , 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, wherein the defined input capacitance is electrically coupled between an output of the unity-gain voltage buffer 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; and
a differential amplifier, wherein the output of the inverting amplifier is electrically coupled to an inverting input of the differential amplifier, and wherein an output of the differential amplifier is electrically coupled to the output of the voltage-to-voltage converter component.

5. The microphone of claim 4 , further comprising a defined parasitic capacitance that is electrically coupled to the input of the voltage-to-voltage converter component.

6. The microphone of claim 5 , 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.

7. The microphone of claim 4 , wherein the output of the inverting amplifier is electrically coupled to the second node of the capacitive sense element.

Assignees

• Invensense Inc

Inventors

• Seeger Joseph
• Shettigar Pradeep

Classifications

• G01P1/006 Primary

  used for thermal compensation · CPC title

• G01P15/00

  Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration · CPC title

• G01P15/125

  by capacitive pick-up · CPC title

• H03F3/45

  Differential amplifiers (differential sense amplifiers G11C7/062) · CPC title

• H03F2200/48

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