# US 2014/0152286 A1 · Analog front-end compensation

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- Number: US 2014/0152286 A1
- Document ID: US20140152286A1
- Status: Published application
- Kind: A1
- Application number: 14/082,914
- Filed: 2013-11-18
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: Sensata Technologies, Inc.
- Inventors: Eric Visser; Keith Kawate
- Web page: https://patentgrep.com/patent/US20140152286A1

## CPC

- G01L 9/12: by making use of variations in capacitance {, i.e. electric circuits therefor}
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)

## Abstract

In an embodiment, an apparatus may include a sense element that may measure a property such as, for example, pressure. The sense element may produce an output based on the measured property. Circuitry associated with the sense element may store a voltage that represents the output produced by the sense element. The circuitry may include, for example, a capacitor which may store the voltage. The stored voltage may include one or more parasitic components such as, for example, an offset voltage and/or voltage associated with current leakage. The circuitry may adjust the stored voltage to compensate for the parasitic components. The adjustment may occur over a series of phases of operation of the circuitry.

## Claims

### Claim 1

An apparatus comprising:
a sense element for:
measuring a property, and producing an output based on the measured property; and
circuitry for:
storing a voltage that represents the output produced by the sense element, and
compensating for one or more parasitic components contained in the stored voltage.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the sense element has a reference capacitance (Cref) and a sense capacitance (Csen).

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein the circuitry further includes:
an amplifier,
a first feedback capacitor (Cb) connected between an output of the amplifier and an input of the amplifier, and
wherein the circuitry further:
adjusts a voltage held by Cb, the voltage being adjusted based on a leakage current associated with the sense element.

### Claim 4 (depends on 3)

The apparatus of claim 3, further comprising:
an input capacitor (Ci) connected between an output of the sense element and the input of the amplifier, Ci holding a voltage associated with a leakage current in the apparatus, and
wherein the voltage held by Cb is adjusted based on an amount of voltage held by Ci.

### Claim 5 (depends on 2)

The apparatus of claim 2, further comprising:
an amplifier,
a first feedback capacitor (Cb) connected between an output of the amplifier and an input of the amplifier, and
an input capacitor (Ci) connected between an output of the sense element and the input of the amplifier, and
wherein the circuitry further:
charges Ci to hold a voltage that is based on a leakage current associated with the sense element, and
injecting the voltage held by Ci into the amplifier to adjust a voltage held by Cb based on the leakage current.

### Claim 6 (depends on 5)

The apparatus of claim 5, wherein the leakage current is defined at least in part based on a resistance associated with at least one of Cref and Csen.

### Claim 7 (depends on 5)

The apparatus of claim 5, wherein the leakage current is defined at least in part based on a leakage current associated with the amplifier.

### Claim 8 (depends on 2)

The apparatus of claim 2, wherein the amplifier includes differential inputs and a single-ended output.

### Claim 9 (depends on 1)

The apparatus of claim 1, wherein the property includes pressure.

### Claim 10 (depends on 1)

The apparatus of claim 1, wherein the sense element is a ceramic sense element (CSE).

### Claim 11 (depends on 2)

The apparatus of claim 2, further comprising:
an amplifier;
a first feedback capacitor (Cb) connected between an output of the amplifier and an input of the amplifier; and
an input capacitor (Ci) connected between an output of the sense element and the input of the amplifier, and
wherein the circuitry further:
charges Ci to hold an offset voltage (V(os)) associated with the amplifier,
senses a value of Csen,
adjusts the voltage held by Ci based on the sensed value,
injects the adjusted voltage held by Ci into the input of the amplifier to adjust a voltage held by Cb.