IMPROVED OFFSET COMPENSATION TECHNOLOGY FOR THE THERMAL CONDUCTIVITY MEASUREMENT OF A GAS CONCENTRATION SENSOR

Abstract

A gas concentration sensor configured to measure the concentration of a target gas includes a reference chamber configured to contain a reference gas; a measurement chamber configured to contain the target gas; and a measurement circuit configurable in a calibration mode and an operating mode. This circuit includes a resistive bridge circuit comprising a first resistive element located in the reference chamber and a second resistive element located in the measurement chamber. The resistive bridge circuit is configured to receive an input voltage and generate a measurement signal based on that input voltage. During calibration mode, the input voltage has an initial voltage value at which the resistive bridge circuit exhibits negligible sensitivity to thermal conductivity, ensuring that the measurement signal is representative of an offset.The measuring circuit is configured to subtract the offset from the measurement signal during operating mode in order to produce a compensated measurement signal.

Description

BACKGROUND

[0001] There is a growing need to reduce petroleum consumption and switch to the use of green energy. For example, hydrogen produced by wind turbines is being considered as a potential green fuel for automotive applications.

[0002] Sensors may be required to detect any escaping hydrogen to prevent the formation of oxyhydrogen. Sensors for measuring a gas property, which can also be referred to as gas sensors, may exhibit cross-sensitivity to various environmental properties, such as humidity, temperature, and / or the flow and concentration of the gas being sensed. In some cases, dedicated sensors for these additional properties must be included to differentiate the signal of interest. For example, a complementary temperature sensor must be added. This can result in a complex device that requires combining different chips or sensing elements within a single package. SUMMARY

[0003] In some implementations, a gas concentration sensor configured to measure a gas concentration of a target gas includes a reference chamber configured to contain a reference gas; a measuring chamber configured to contain a target gas that is different from the reference gas; and a measuring circuit configurable in a calibration mode and an operation mode, the measuring circuit comprising: a full-bridge circuit comprising a first piezoresistive wire disposed in the reference chamber and exposed to the reference gas, a second piezoresistive wire disposed in the reference chamber and exposed to the reference gas, a third piezoresistive wire disposed in the measuring chamber and exposed to the target gas, and a fourth piezoresistive wire disposed in the measuring chamber and exposed to the target gas,wherein the full-bridge circuit is configured to receive an input voltage and generate a difference signal based on the input voltage, wherein during the calibration mode, the input voltage has a first voltage value at which the full-bridge circuit has negligible sensitivity to thermal conductivity, such that the difference signal is representative of an offset, wherein during the operating mode, the input voltage has a second voltage value at which the full-bridge circuit is sensitive to thermal conductivity with an operating sensitivity, such that the difference signal is representative of a thermal conductivity of the target gas, wherein the measuring circuit is configured to measure the offset based on the difference signal during the calibration mode, and wherein the measuring circuit is configured to subtract the offset from the difference signal during the operating mode,to generate a compensated difference signal.

[0004] In some implementations, a gas concentration sensor configured to measure a gas concentration of a target gas includes a reference chamber configured to contain a reference gas; a measurement chamber configured to contain the target gas that is different from the reference gas; and a measurement circuit configurable in a calibration mode and an operation mode, wherein the measurement circuit comprises: a resistive bridge circuit comprising a plurality of resistive elements, including at least a first resistive element disposed in the reference chamber and at least one second resistive element disposed in the measurement chamber, wherein the resistive bridge circuit is configured to receive an input voltage and generate a measurement signal based on the input voltage, wherein during the calibration mode, the input voltage has a first voltage value,wherein the resistance bridge circuit has a negligible sensitivity to thermal conductivity such that the measurement signal is representative of an offset, wherein during the operating mode the input voltage has a second voltage value at which the resistance bridge circuit is sensitive to thermal conductivity with an operating sensitivity such that the measurement signal is representative of a thermal conductivity of the target gas, wherein the measurement circuit is configured to measure the offset based on the measurement signal during the calibration mode, and wherein the measurement circuit is configured to subtract the offset from the measurement signal during the operating mode to generate a compensated measurement signal.

[0005] In some implementations, a method for calibrating an offset of a gas concentration sensor includes configuring a measuring circuit of the gas concentration sensor in a calibration mode; applying, during the calibration mode, a first input voltage to a resistive bridge circuit of the gas concentration sensor to cause the resistive bridge circuit to generate a first measurement signal, wherein based on the first input voltage, the resistive bridge circuit has negligible sensitivity to thermal conductivity such that the first measurement signal is representative of the offset; configuring, during the calibration mode, a compensation component of the measuring circuit with the offset derived from the first measurement signal; configuring the measuring circuit of the gas concentration sensor in an operating mode;Applying, during the operating mode, a second input voltage to the resistive bridge circuit of the gas concentration sensor to cause the resistive bridge circuit to generate a second measurement signal, wherein the second input voltage is greater than the first input voltage, and wherein, based on the second input voltage, the resistive bridge circuit is sensitive to thermal conductivity with an operating sensitivity such that the second measurement signal is representative of a thermal conductivity of a measurement gas; and subtracting, during the operating mode, the offset configured on the compensation component from the second measurement signal to generate a compensated measurement signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Implementations are described herein with reference to the accompanying drawings. Fig. 1 illustrates a gas sensor according to one or more implementations. Fig. 2 illustrates a resistive bridge circuit according to one or more implementations. Fig. 3 illustrates a schematic block diagram of a gas sensor measurement circuit according to one or more implementations. DETAILED DESCRIPTION

[0007] Details are set forth below to provide a more thorough explanation of example implementations. However, it will be apparent to one skilled in the art that these implementations may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form or in a schematic view rather than in detail to avoid obscuring the implementations. Furthermore, features of the various implementations described below may be combined with one another unless expressly stated otherwise.

[0008] Furthermore, equivalent or identical elements, or elements with equivalent or identical functionality, are denoted by equivalent or identical reference numerals in the following description. Since the same or functionally equivalent elements are denoted by the same reference numerals in the figures, a repeated description for elements denoted by the same reference numerals can be omitted. Therefore, descriptions provided for elements with the same or identical reference numerals are interchangeable.

[0009] The orientations of the various elements in the figures are shown as examples, and the illustrated examples may be rotated relative to the depicted orientations. The descriptions provided herein and the following claims apply to any structures having the described relationships between various features, whether the structures are in the particular orientation of the drawings or rotated relative to such orientation. Likewise, spatially relative terms such as "top," "bottom," "below," "beneath," "lower," "above," "upper," "middle," "left," and "right" are used herein for ease of description to describe the relationship of one element to one or more other elements as illustrated in the figures.The spatially relative terms are intended to encompass various orientations of the element, structure, and / or assembly in use or operation in addition to the orientations depicted in the figures. A structure and / or assembly may be oriented differently (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein may be interpreted accordingly. Furthermore, the cross-sectional views in the figures show only features within the planes of the cross sections and do not show materials behind the planes of the cross sections unless otherwise noted to simplify the drawings.

[0010] It should be understood that when an element is described as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is described as being "directly connected" or "directly coupled" to another element, no intervening elements are present. Other words used to describe the relationship between elements should be interpreted similarly (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.).

[0011] In implementations described herein or shown in the drawings, any direct electrical connection or coupling (e.g., any connection or coupling without additional intervening elements) may also be implemented by an indirect connection or coupling (e.g., a connection or coupling with one or more additional intervening elements, or vice versa), as long as the general purpose of the connection or coupling (e.g., to transmit a particular type of signal or to transmit a particular type of information) is substantially maintained. Features from different implementations may be combined to form further implementations. For example, variations or modifications described with respect to one of the implementations may also be applicable to other implementations, unless otherwise stated.

[0012] For example, the terms "substantially" and "approximately" may be used herein to account for small manufacturing tolerances or other factors (e.g., within 5%) that are considered acceptable in the industry without deviating from the aspects of the implementations described herein. For example, a resistor with an approximate resistance value may practically have a resistance within 5% of the approximate resistance value. As another example, a signal with an approximate signal value may practically have a signal value within 5% of the approximate signal value.

[0013] In the present disclosure, terms, including ordinal numbers such as "first," "second," and / or the like, may modify various elements. However, such elements are not limited by such terms. For example, such terms do not limit the order and / or importance of the elements. Instead, such terms are used solely for the purpose of distinguishing one element from the other elements. For example, a first box and a second box indicate different boxes even though both are boxes. For further example, a first element could be referred to as a second element, and similarly, a second element could also be referred to as a first element, without departing from the scope of the present disclosure.

[0014] A "sensor" can refer to a component that converts a property to be measured into an electrical signal (e.g., a current signal or a voltage signal). The property to be measured can include, but is not limited to, a magnetic field, an electric field, an electromagnetic wave (e.g., a radio wave), pressure, force, current, or voltage. A gas sensor can measure a property of a gas, such as a thermal conductivity of the gas. Based on the measured property, a presence of the gas can be detected. Additionally, a concentration of the gas can be measured based on the measured property.

[0015] For example, a gas sensor can measure the thermal conductivity of a target gas by heating four resistance wires connected in a Wheatstone bridge configuration (e.g., a full-bridge resistor circuit), where two reference resistance wires are insulated in a stable reference gas and two measuring resistance wires are exposed to a measurement gas that may contain the target gas. The four resistance wires can experience a temperature change (e.g., a temperature increase) by applying a voltage across two input terminals of the Wheatstone bridge configuration. The two reference resistance wires can release heat to the stable reference gas based on a thermal conductivity of the stable reference gas (e.g., the higher the thermal conductivity of a gas, the more heat is conducted through and released to the gas).In other words, a temperature change and thus a resistance change of the two reference resistance wires can depend on a rate of thermal release of heat from the two reference resistance wires to the stable reference gas, which can depend on the thermal conductivity of the stable reference gas. The thermal conductivity of the stable reference gas is a known parameter. The two measuring resistance wires can release heat to the measuring gas based on a thermal conductivity of the measuring gas. In other words, a temperature change and thus a resistance change of the two measuring resistance wires can depend on a rate of thermal release of heat from the two measuring resistance wires to the measuring gas, which can depend on the thermal conductivity of the measuring gas. The thermal conductivity of the measuring gas is an unknown parameter.For example, the thermal conductivity of the sample gas may be related to a concentration of the target gas in the sample gas.

[0016] The gas sensor can be configured to measure a differential signal output from the Wheatstone bridge configuration. The differential signal can represent a change in the resistance of the measuring resistance wires compared to a change in the resistance of the reference resistance wires, which are generated by different rates of thermal release from the four resistance wires to the measurement gas and the stable reference gas, respectively. Thus, the concentration of the target gas can be measured based on the differential signal.

[0017] The differential signal used to measure the concentration of the target gas can be significantly smaller than offsets caused by external influences, such as ambient temperature, ambient pressure, production variation of the gas sensor, and lifetime drift. These offsets can make it difficult for the gas sensor to obtain useful information from the differential signal. Thus, the offsets should be discarded to obtain useful information from the differential signal.

[0018] In some cases, offset compensation can be performed in a digital domain by either implementing a compensation polynomial function that accounts for all offset factors, or by deriving an offset directly from the gas sensor readout by applying a nominal voltage and taking the readout before the four resistance wires are heated. However, both methods, performed in the digital domain, have a problem in that they impose a very large dynamic range on the entire analog signal path of the gas sensor. A dynamic range is a range of variables over which an external influence can vary. For example, an ambient temperature dynamic range can include all ambient temperatures in which the gas sensor must operate (e.g., -20° to over 100° F). Similarly, an ambient temperature dynamic range can include all ambient pressures in which the gas sensor must operate.The dynamic range of each external influence should be considered when compensating for offsets. Furthermore, the compensation polynomial function is complex, requires significant processing power, and may not be able to accurately account for all offset factors across the respective dynamic ranges.

[0019] Some implementations disclosed herein aim to reduce the effect of an offset magnitude on a downstream signal path by performing an initial offset compensation measurement as an initial compensation step. The initial offset compensation measurement may be performed by applying a low input supply voltage (e.g., about 1 V) across two input terminals of a resistive bridge circuit (e.g., a Wheatstone bridge configuration) and reading a measurement signal (e.g., a differential signal) of the resistive bridge circuit while applying the low input supply voltage. During the initial offset compensation measurement, a sensitivity of the resistive bridge circuit to thermal conductivity may be zero or near zero, while non-gas offset effects (e.g.,external influences, such as ambient temperature, ambient pressure, production variation of the gas sensor, and lifetime drift) are still measurable. Thus, the non-gas offset effects can be isolated from the thermal conductivity sensitivity of the gas sensor. As a result, during the initial offset compensation measurement, the non-gas offset effects can be measured independently of the thermal conductivity sensitivity of the gas sensor to obtain an accurate measurement of all non-gas offset effects in a single measurement without considering the non-gas offset effects in each respective dynamic range. In other words, a single offset can be measured that accounts for all non-gas offset effects. Accordingly, the complexity of considering all non-gas offset effects for offset compensation can be reduced. As a result, the processing power of the gas sensor can also be reduced.

[0020] Since the magnitude of the measurement signal at the output of the resistor bridge circuit is directly proportional to the input supply voltage, using a low input supply voltage can further reduce the magnitude of the offset, which can reduce the signal processing requirements on the analog signal path of the gas sensor. In other words, the processing components arranged on the analog signal path can be simplified, which can reduce the complexity and manufacturing cost of the gas sensor.

[0021] The offset measured during the initial offset compensation measurement can then be scaled according to a scaling factor and then fed back to the analog signal path and subtracted from a measurement signal generated during an operating mode of the gas sensor. Thus, the measurement signal generated during the operating mode of the gas sensor can be compensated by the offset measured during the initial offset compensation measurement. The scaling factor can be determined based on a ratio of the input supply voltage used during the operating mode (e.g., 5 V) and the low input supply voltage used during the initial offset compensation measurement (e.g., 1 V). For example, the scaling factor can be 5 if the input supply voltage used during the operating mode is 5 V and the low input supply voltage used during the initial offset compensation measurement is 1 V.By subtracting the offset from the measurement signal during operation, a significantly smaller residual offset is output from the analog signal path, which can be more easily compensated by other techniques in the digital domain. Because the residual offset is much smaller than would otherwise be present at an analog signal path output, the signal processing requirements of a digital signal path can be reduced, which can lead to reduced processing power, reduced complexity, and reduced manufacturing costs of the gas sensor.

[0022] Fig. 1 illustrates a gas sensor 100 according to one or more implementations. The gas sensor 100 may be a thermal conductivity (TC) sensor that uses a known thermal conductivity of a reference gas to measure a concentration of a target gas contained in a measurement gas. For example, the gas sensor 100 may be configured to measure a thermal conductivity of the measurement gas based on a measurement signal and determine the concentration of the target gas based on the thermal conductivity of the measurement gas.

[0023] The gas sensor 100 may include a housing 102 or a casing that includes a reference chamber 104 configured to contain a reference gas and a measurement chamber 106 configured to contain a measurement gas (e.g., an ambient gas) that is different from the reference gas. The reference gas may be, but is not limited to, oxygen or nitrogen. In some implementations, the reference gas may be a vacuum gas. The measurement gas may be the target gas or may include the target gas. The target gas may be absent from the reference gas. The reference chamber 104 may be a sealed chamber. For example, in some implementations, the reference chamber 104 may be hermetically sealed. Furthermore, the housing 102 may include an opening 108 (e.g., a conduit) that allows the measurement gas to enter the measurement chamber 106. Thus, the opening 108 may be provided to fluidly connect the measurement chamber 106 to the measurement gas.

[0024] The gas sensor 100 may include a plurality of resistive elements, such as piezoresistive wires. The plurality of resistive elements may have a substantially identical resistivity when the gas sensor 100 is in an off state (e.g., when no input supply voltage is applied to the plurality of resistive elements). In some implementations, the gas sensor 100 may include a first piezoresistive wire 110, a second piezoresistive wire 112, a third piezoresistive wire 114, and a fourth piezoresistive wire 116.The first piezoresistive wire 110 may be disposed in the reference chamber 104 and may be exposed to the reference gas, the second piezoresistive wire 112 may be disposed in the reference chamber 104 and may be exposed to the reference gas, the third piezoresistive wire 114 may be disposed in the measurement chamber 106 and may be exposed to the measurement gas, and the fourth piezoresistive wire 116 may be disposed in the measurement chamber 106 and may be exposed to the measurement gas.

[0025] The plurality of resistance elements may be provided in a resistance bridge circuit, such as a full-bridge circuit (e.g., a Wheatstone bridge). In other words, the plurality of resistance elements may be connected in a full-bridge configuration including two input terminals to which an input voltage is applied and two output terminals from which a differential signal (e.g., a differential voltage) is output as a measurement signal. In other words, the full-bridge circuit may be configured to receive the input voltage and generate the differential signal at a differential output of the resistance bridge circuit based on the input voltage. The first piezoresistive wire 110 and the second piezoresistive wire 112 may be arranged on opposite segments of the full-bridge circuit.For example, the full-bridge circuit may include two half-bridges, including a first half-bridge and a second half-bridge. The first piezoresistive wire 110 may be disposed in the first half-bridge, and the second piezoresistive wire 112 may be disposed in the second half-bridge. The first piezoresistive wire 110 may be disposed diagonally across the second piezoresistive wire 112. The third piezoresistive wire 114 and the fourth piezoresistive wire 116 may also be disposed on opposite segments of the full-bridge circuit. For example, the third piezoresistive wire 114 may be disposed in the first half-bridge, and the fourth piezoresistive wire 116 may be disposed in the second half-bridge. The third piezoresistive wire 114 may be disposed diagonally across the fourth piezoresistive wire 116. Thus, each half-bridge is formed by a piezoresistive measuring wire and a piezoresistive reference wire.

[0026] In some implementations, only a single half-bridge may be used. For example, the plurality of resistive elements may include only two resistive wires. In this case, the resistive bridge circuit may include, for example, only the first piezoresistive wire 110 and the third piezoresistive wire 114. The single half-bridge may be configured to output a measurement signal from an output node disposed and coupled between the two resistive wires. The measurement signal may represent a change in the resistance of the first piezoresistive wire 110 compared to a change in the resistance of the third piezoresistive wire 114, generated by different rates of thermal release from the two resistive wires to the measurement gas and the reference gas, respectively. Thus, the concentration of the target gas may be measured based on the measurement signal.

[0027] As stated above, Fig. 1 is provided as an example. Other examples may differ from what is stated in relation to Fig. 1. The number and arrangement of devices and components shown in Fig. 1 are provided as an example. In practice, additional devices or components, fewer devices or components, different devices or components, or differently arranged devices or components than those shown in Fig. 1 shown.

[0028] Fig. 2 illustrates a resistive bridge circuit 200 according to one or more implementations. The resistive bridge circuit 200 may include the first piezoresistive wire 110, the second piezoresistive wire 112, the third piezoresistive wire 114, and the fourth piezoresistive wire 116 connected in a full-bridge configuration. The resistive bridge circuit 200 includes a first half-bridge on a left side and a second half-bridge on a right side. The first piezoresistive wire 110 may be disposed in the first half-bridge, and the second piezoresistive wire 112 may be disposed in the second half-bridge. The first piezoresistive wire 110 may be disposed diagonally across the second piezoresistive wire 112. The third piezoresistive wire 114 and the fourth piezoresistive wire 116 may also be arranged on opposite segments of the full bridge circuit.For example, the third piezoresistive wire 114 can be arranged in the first half-bridge, and the fourth piezoresistive wire 116 can be arranged in the second half-bridge. The third piezoresistive wire 114 can be arranged diagonally above the fourth piezoresistive wire 116. Thus, each half-bridge is formed by a piezoresistive measuring wire and a piezoresistive reference wire.

[0029] The resistance bridge circuit 200 may include two input terminals, including a first input terminal 201 and a second input terminal 202. An input voltage Vin may be applied to the first input terminal 201 and the second input terminal 202. In other words, the input voltage Vin is applied across the two input terminals. A voltage level of the input voltage Vin may be controlled by a controller. The resistance bridge circuit 200 may further include two output terminals, including a first output terminal 203 and a second output terminal 204. Applying the input voltage Vin to the two input terminals causes the resistance bridge circuit 200 to generate a differential signal Vout (e.g., an output voltage) at the two output terminals.The differential signal Vout can be measured via the two output terminals and can be used by the gas sensor 100 as a measurement signal.

[0030] The differential signal Vout may depend on the voltage level of the input voltage Vin and the respective resistances of the first piezoresistive wire 110, the second piezoresistive wire 112, the third piezoresistive wire 114, and the fourth piezoresistive wire 116. For example, the first piezoresistive wire 110, the second piezoresistive wire 112, the third piezoresistive wire 114, and the fourth piezoresistive wire 116 may experience a temperature change (e.g., a temperature increase) by applying or increasing the input voltage Vin across the two input terminals 201 and 202 of the resistive bridge circuit 200. Alternatively, the piezoresistive wires 110, 112, 114, and 116 may experience a temperature decrease by either reducing the input voltage Vin or removing the input voltage Vin.

[0031] Upon applying the input voltage Vin (e.g., from an off state) or increasing the input voltage Vin, the piezoresistive wires 110, 112, 114, and 116 may heat up depending on the voltage level of the input voltage Vin. Temperature change of the piezoresistive wires 110, 112, 114, and 116 may occur at different rates based on exposure of the first piezoresistive wire 110 and the second piezoresistive wire 112 to the reference gas and based on exposure of the third piezoresistive wire 114 and the fourth piezoresistive wire 116 to the measurement gas.

[0032] For example, the first piezoresistive wire 110 and the second piezoresistive wire 112 may release heat to the reference gas based on a thermal conductivity of the reference gas. In other words, a temperature change, and thus a resistance change, of the first piezoresistive wire 110 and the second piezoresistive wire 112 may depend on a rate of thermal release of heat from the first piezoresistive wire 110 and the second piezoresistive wire 112 to the reference gas, which may depend on the thermal conductivity of the reference gas.

[0033] The third piezoresistive wire 114 and the fourth piezoresistive wire 116 can release heat to the measurement gas based on a thermal conductivity of the measurement gas. In other words, a temperature change, and thus a resistance change, of the third piezoresistive wire 114 and the fourth piezoresistive wire 116 can depend on a rate of thermal release of heat from the third piezoresistive wire 114 and the fourth piezoresistive wire 116 to the measurement gas, which can depend on the thermal conductivity of the measurement gas, which can be related to a concentration of the target gas in the measurement gas.

[0034] The gas sensor 100 may be configured to measure the differential signal Vout output from the resistance bridge circuit 200. The differential signal Vout may represent a change in the resistance of the third piezoresistive wire 114 and the fourth piezoresistive wire 116 relative to a change in the resistance of the first piezoresistive wire 110 and the second piezoresistive wire 112, which are generated by different rates of thermal release from the piezoresistive wires to the measurement gas and the reference gas, respectively. Thus, the concentration of the target gas can be measured based on the differential signal Vout.

[0035] As stated above, Fig. 2 is provided as an example. Other examples may differ from what is stated in relation to Fig. 2 is described.

[0036] Fig. 3 illustrates a schematic block diagram of a measuring circuit 300 of a gas concentration sensor according to one or more implementations. The measuring circuit 300 may be used as part of the system associated with Fig. 1 and Fig. 2. For example, the measurement circuit 300 may include the piezoresistive wires 110, 112, 114, and 116 arranged in the resistance bridge circuit 200. Furthermore, the measurement circuit 300 may include a controller 302, a subtractor 304 (e.g., a subtraction component) arranged on an analog signal path, an analog-to-digital converter (ADC) 306, a scaler 308 (e.g., a multiplier), an offset digital-to-analog converter (DAC) 310, and a digital signal processing circuit 312. The scaler 308 and the offset DAC 310 may be arranged in a compensation feedback path.

[0037] The controller 302 may be a supply voltage controller that may be configured to control a voltage level of the input voltage Vin. For example, the measurement circuit 300 may be configurable in a calibration mode and an operation mode. During the calibration mode, the measurement circuit 300 may be configured to measure an offset that accounts for one or more non-gas offset effects. During the operation mode, the measurement circuit 300 may be configured to measure a concentration of the target gas that may be present in the measurement gas.

[0038] During the operation mode, the measurement circuit 300 may compensate the difference signal Vout output from the resistance bridge circuit 200 based on the offset measured during the calibration mode to generate a compensated difference signal Vout'.

[0039] During the calibration mode, the controller 302 may control the input voltage Vin such that the input voltage Vin has a first voltage value at which the resistive bridge circuit 200 has negligible sensitivity to thermal conductivity, such that the difference signal Vout is representative of an offset (e.g., an offset value). In other words, at the first voltage value, the piezoresistive wires 110, 112, 114, and 116 may be substantially insensitive to thermal conductivity and primarily sensitive to non-gas offset effects. Thus, during the calibration mode, the difference signal Vout may be sensitive to the non-gas offset effects and may not be affected (e.g., to a measurable extent) by a thermal conductivity of the measurement gas and a thermal conductivity of the reference gas.In contrast, during the operating mode, the controller 302 may control the input voltage Vin such that the input voltage Vin has a second voltage value at which the resistive bridge circuit 200 is sensitive to thermal conductivity with an operating sensitivity such that the difference signal Vout is representative of a thermal conductivity of the measurement gas (e.g., the target gas). In other words, the piezoresistive wires 110, 112, 114, and 116 may be sensitive to the thermal conductivity of the measurement gas and the thermal conductivity of the reference gas at the second voltage value. Thus, the difference signal Vout may be influenced by the thermal conductivity of the measurement gas during the operating mode.Thus, by configuring the measurement circuit 300 in calibration mode, the offset induced by the non-gas offset effects can be isolated from the thermal conductivity and used to compensate the difference signal Vout during the operation mode.

[0040] The measurement circuit 300 may be configured to measure the offset based on the difference signal Vout during the calibration mode and to subtract the offset (e.g., the offset value) from the difference signal Vout during the operation mode to generate the compensated difference signal Vout'. As a result, the compensated difference signal Vout' may be a more accurate representation of the thermal conductivity of the measurement gas (e.g., the target gas) than the difference signal Vout during the operation mode.

[0041] The first voltage value is less than the second voltage value. For example, in some implementations, the first voltage value may be less than 1.5 V and the second voltage value may be greater than 3.5 V. The first voltage value may be set such that the negligible sensitivity to thermal conductivity is at least two orders of magnitude smaller than the operating sensitivity to thermal conductivity. In other words, the piezoresistive wires 110, 112, 114, and 116 may be at least 100 times less sensitive to thermal conductivity during calibration mode than during operating mode.

[0042] During the calibration mode, the input voltage Vin may cause the first piezoresistive wire 110, the second piezoresistive wire 112, the third piezoresistive wire 114, and the fourth piezoresistive wire 116 to experience a negligible temperature change such that the difference signal Vout is a measure of at least one offset effect (e.g., at least one non-gas offset effect, such as pressure, temperature, production variation, or lifetime drift). For example, during the calibration mode, the input voltage Vin may cause the first piezoresistive wire 110 and the second piezoresistive wire 112 to experience a first change in resistance based on at least one offset effect, and may cause the third piezoresistive wire 114 and the fourth piezoresistive wire 116 to experience a second change in resistance based on the at least one offset effect.

[0043] During the operating mode, the input voltage Vin may cause the first piezoresistive wire 110 and the second piezoresistive wire 112 to experience a first temperature increase based on a first rate of thermal release to the reference gas, and may cause the third piezoresistive wire 114 and the fourth piezoresistive wire 116 to experience a second temperature increase based on a second rate of thermal release to the target gas. For example, during the operating mode, the input voltage Vin may cause the first piezoresistive wire 110 and the second piezoresistive wire 112 to experience a third change in resistance based on a first thermal interaction of the first piezoresistive wire 110 and the second piezoresistive wire 112 with the reference gas.Additionally, during the operating mode, the input voltage Vin causes the third piezoresistive wire 114 and the fourth piezoresistive wire 116 to experience a fourth change in resistance based on a second thermal interaction of the third piezoresistive wire 114 and the fourth piezoresistive wire 116 with the measurement gas (e.g., with the target gas). In other words, during the operating mode, the input voltage Vin may cause the first piezoresistive wire 110 and the second piezoresistive wire 112 to experience the third change in resistance based on a thermal conductivity of the reference gas, and may cause the third piezoresistive wire 114 and the fourth piezoresistive wire 116 to experience the fourth change in resistance based on the thermal conductivity of the target gas (e.g., the target gas).

[0044] The subtractor 304 may be configured to receive the difference signal Vout from the resistive bridge circuit 200. During the calibration mode, the offset DAC 310 may not provide an analog offset signal to the subtractor 304 (e.g., an output of the offset DAC 310 may be disabled or set to zero). As a result, during the calibration mode, the difference signal Vout may pass through the subtractor 304 unchanged. In other words, during the calibration mode, the subtractor 304 may output the difference signal Vout to the ADC 306. During the operation mode, the offset DAC 310 may provide the analog offset signal having an offset value determined during the calibration mode, and the subtractor 304 may subtract the offset value from the difference signal Vout to generate the compensated difference signal Vout'.

[0045] The ADC 306 is coupled to an output of the subtractor 304. During the calibration mode, the ADC 306 may generate a digital signal Dout based on the difference signal Vout provided by the subtractor 304. For example, the ADC 306 may convert the difference signal Vout into the digital signal Dout. The digital signal Dout is proportional to the offset based on a ratio of the second voltage value to the first voltage value. Thus, during the calibration mode, the scaler 308 may upscale or multiply the digital signal Dout by a scaling factor to generate a scaled digital signal Dx equal to the offset (e.g., equal to the offset value to be applied to the subtractor 304 during the operation mode). The scaling factor may be equal to the ratio of the second voltage value to the first voltage value.For example, if the second voltage value is 5 V and the first voltage value is 1 V, the scaling factor is 5. Thus, the scaled digital signal Dx may be 5 times larger than the digital signal Dout. The offset DAC 310 may receive the scaled digital signal Dx and generate the analog offset signal based on the scaled digital signal Dx. For example, during calibration mode, the offset DAC 310 may convert the scaled digital signal Dx to an analog value and store the analog value as the offset value to be used during operation mode. During operation mode, the offset DAC 310 may output the analog offset signal with the stored offset value to be subtracted from the difference signal by the subtractor 304.Accordingly, during the operating mode, the subtractor 304 can generate the compensated difference signal Vout' by subtracting the offset value from the difference signal Vout to perform offset compensation. Finally, during the operating mode, the ADC 306 can convert the compensated difference signal Vout' into a digital measurement signal Dout representative of the thermal conductivity of the measurement gas (e.g., the target gas). The ADC 306 can provide the digital measurement signal Dout to the digital signal processing circuit 312 for further digital processing.

[0046] Accordingly, a single offset can be measured during calibration mode, accounting for one or more (e.g., all) non-gas offset effects. Accordingly, the complexity of considering all non-gas offset effects for offset compensation can be reduced. Consequently, the processing power of the gas sensor can also be reduced.

[0047] Since a magnitude of the differential signal Vout is directly proportional to the input supply voltage, using a low input voltage can further reduce the magnitude of the offset, which can reduce the signal processing requirements on the analog signal path of the gas sensor 100. In other words, processing components arranged on the analog signal path can be simplified, which can reduce the complexity and manufacturing costs of the gas sensor 100. Furthermore, by subtracting the offset from the differential signal Vout during the operating mode, a significantly smaller residual offset is output from the analog signal path, which can be more easily compensated by other techniques in the digital domain.Because the residual offset is much smaller than would otherwise be present at an output of the analog signal path, the signal processing requirements of a digital signal path of the digital signal processing circuit 312 can be reduced, which can result in reduced processing power, reduced complexity, and reduced manufacturing costs of the digital signal processing circuit 312.

[0048] As stated above, Fig. 3 is provided as an example. Other examples may differ from what is stated in relation to Fig. 3. The number and arrangement of devices and components shown in Fig. 3 are provided as an example. In practice, additional devices or components, fewer devices or components, different devices or components, or differently arranged devices or components than those shown in Fig.3 shown must be present.

[0049] The following provides an overview of some aspects of the present disclosure: Aspect 1: A gas concentration sensor configured to measure a gas concentration of a target gas, comprising: a reference chamber configured to contain a reference gas; a measuring chamber configured to contain a target gas different from the reference gas; and a measuring circuit configurable in a calibration mode and an operating mode, the measuring circuit comprising: a full-bridge circuit comprising a first piezoresistive wire arranged in the reference chamber and exposed to the reference gas, a second piezoresistive wire arranged in the reference chamber and exposed to the reference gas, a third piezoresistive wire arranged in the measuring chamber and exposed to the target gas, and a fourth piezoresistive wire arranged in the measuring chamber and exposed to the target gas, wherein the full-bridge circuit is configured to receive an input voltage and generate a difference signal based on the input voltage, wherein during the calibration mode the input voltage has a first voltage value at which the full-bridge circuit has negligible sensitivity to thermal conductivity such that the difference signal is representative of an offset, wherein during the operation mode the input voltage has a second voltage value at which the full-bridge circuit is sensitive to thermal conductivity with an operating sensitivity such that the difference signal is representative of a thermal conductivity of the target gas, wherein the measuring circuit is configured to measure the offset based on the difference signal during the calibration mode, and wherein the measuring circuit is configured to subtract the offset from the difference signal during the operation mode to generate a compensated difference signal. Aspect 2: A gas concentration sensor according to aspect 1, wherein during the operating mode the compensated difference signal is a more accurate representation of the thermal conductivity of the target gas than the difference signal. Aspect 3: The gas concentration sensor according to any one of aspects 1-2, wherein the first voltage value is smaller than the second voltage value. Aspect 4: A gas concentration sensor according to any one of aspects 1-3, wherein the negligible sensitivity to thermal conductivity is at least two orders of magnitude smaller than the operating sensitivity to thermal conductivity. Aspect 5: The gas concentration sensor of any one of aspects 1-4, wherein during the calibration mode, the input voltage causes the first piezoresistive wire, the second piezoresistive wire, the third piezoresistive wire, and the fourth piezoresistive wire to experience a negligible temperature change such that the difference signal is a measure of at least one offset effect. Aspect 6: The gas concentration sensor of aspect 5, wherein the at least one offset effect includes at least one of pressure, temperature, production variation, or lifetime drift. Aspect 7: The gas concentration sensor of aspect 5, wherein during the operating mode, the input voltage causes the first piezoresistive wire and the second piezoresistive wire to experience a first temperature increase based on a first rate of thermal release to the reference gas, and wherein during the operating mode, the input voltage causes the third piezoresistive wire and the fourth piezoresistive wire to experience a second temperature increase based on a second rate of thermal release to the target gas. Aspect 8: The gas concentration sensor of any one of aspects 1-7, wherein the measurement circuit further comprises: a subtraction component configured to receive the difference signal, wherein the subtraction component is configured to output the difference signal during the calibration mode, and wherein the subtraction component is configured to subtract the offset from the difference signal during the operation mode to generate the compensated difference signal. Aspect 9: The gas concentration sensor of aspect 8, wherein the measurement circuit further comprises: an ADC coupled to an output of the subtraction component, the ADC configured to generate a digital signal based on the difference signal during the calibration mode; a scaler configured to upscale the digital signal by a scaling factor during the calibration mode to generate a scaled digital signal equal to the offset, the scaling factor being equal to a ratio of the second voltage value to the first voltage value; and a DAC configured to receive the scaled digital signal and generate an analog offset signal based on the scaled digital signal. Aspect 10: The gas concentration sensor of aspect 9, wherein the DAC is configured to provide the analog offset signal to the subtraction component during the operating mode, and wherein the subtraction component is configured to subtract the analog offset signal from the difference signal during the operating mode to generate the compensated difference signal. Aspect 11: The gas concentration sensor of aspect 9, wherein the ADC is configured to convert the compensated difference signal into a digital measurement signal representative of the thermal conductivity of the target gas during the operating mode. Aspect 12: A gas concentration sensor configured to measure a gas concentration of a target gas, comprising: a reference chamber configured to contain a reference gas; a measuring chamber configured to contain the target gas that is different from the reference gas; and a measuring circuit configurable in a calibration mode and an operation mode, wherein the measuring circuit comprises: a resistance bridge circuit comprising a plurality of resistance elements, including at least a first resistance element disposed in the reference chamber and at least one second resistance element disposed in the measuring chamber, wherein the resistance bridge circuit is configured to receive an input voltage and generate a measurement signal based on the input voltage, wherein during the calibration mode, the input voltage has a first voltage value,wherein the resistance bridge circuit has a negligible sensitivity to thermal conductivity such that the measurement signal is representative of an offset, wherein during the operating mode the input voltage has a second voltage value at which the resistance bridge circuit is sensitive to thermal conductivity with an operating sensitivity such that the measurement signal is representative of a thermal conductivity of the target gas, wherein the measurement circuit is configured to measure the offset based on the measurement signal during the calibration mode, and wherein the measurement circuit is configured to subtract the offset from the measurement signal during the operating mode to generate a compensated measurement signal. Aspect 13: A gas concentration sensor according to aspect 12, wherein during the operating mode the compensated measurement signal is a more accurate representation of the thermal conductivity of the target gas than the measurement signal. Aspect 14: The gas concentration sensor according to any one of aspects 12-13, wherein the first voltage value is smaller than the second voltage value. Aspect 15: A gas concentration sensor according to any one of aspects 12-14, wherein the negligible sensitivity to thermal conductivity is at least two orders of magnitude smaller than the operating sensitivity to thermal conductivity. Aspect 16: The gas concentration sensor of any one of aspects 12-15, wherein during the calibration mode, the input voltage causes the at least one first resistive element to experience a first change in resistance based on at least one offset effect, and wherein during the calibration mode, the input voltage causes the at least one second resistive element to experience a second change in resistance based on the at least one offset effect. Aspect 17: The gas concentration sensor of aspect 16, wherein during the operating mode, the input voltage causes the at least one first resistive element to experience a third change in resistance based on a first thermal interaction of the at least one first resistive element with the reference gas, and wherein during the operating mode, the input voltage causes the at least one second resistive element to experience a fourth change in resistance based on a second thermal interaction of the at least one second resistive element with the target gas. Aspect 18: The gas concentration sensor of aspect 16, wherein during the operating mode, the input voltage causes the at least one first resistive element to experience a third change in resistance based on a thermal conductivity of the reference gas, and wherein during the operating mode, the input voltage causes the at least one second resistive element to experience a fourth change in resistance based on the thermal conductivity of the target gas. Aspect 19: A method for calibrating an offset of a gas concentration sensor, the method comprising: configuring a measuring circuit of the gas concentration sensor in a calibration mode; applying, during the calibration mode, a first input voltage to a resistive bridge circuit of the gas concentration sensor to cause the resistive bridge circuit to generate a first measurement signal, wherein based on the first input voltage, the resistive bridge circuit has negligible sensitivity to thermal conductivity such that the first measurement signal is representative of the offset; configuring, during the calibration mode, a compensation component of the measuring circuit with the offset derived from the first measurement signal; configuring the measuring circuit of the gas concentration sensor in an operating mode;Applying, during the operating mode, a second input voltage to the resistive bridge circuit of the gas concentration sensor to cause the resistive bridge circuit to generate a second measurement signal, wherein the second input voltage is greater than the first input voltage, and wherein, based on the second input voltage, the resistive bridge circuit is sensitive to thermal conductivity, with an operating sensitivity such that the second measurement signal is representative of a thermal conductivity of a measurement gas; and subtracting, during the operating mode, the offset configured on the compensation component from the second measurement signal to generate a compensated measurement signal. Aspect 20: The method of aspect 19, wherein the negligible sensitivity to thermal conductivity is at least two orders of magnitude smaller than the operating sensitivity to thermal conductivity. Aspect 21: System configured to perform one or more operations listed in one or more of Aspects 1-20. Aspect 22: Apparatus comprising means for performing one or more operations listed in one or more of aspects 1-20. Aspect 23: A non-transitory computer-readable medium storing a set of instructions, the set of instructions comprising one or more instructions that, when executed by a device, cause the device to perform one or more operations recited in one or more of aspects 1-20. Aspect 24: A computer program product comprising instructions or code for performing one or more operations listed in one or more of aspects 1-20.

[0050] The above disclosure provides illustration and description, but is not intended to be exhaustive or to limit implementations to the precise form disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of the implementations.

[0051] Some implementations may be described herein in connection with thresholds. As used herein, "meeting" a threshold may refer to a value that is greater than the threshold, more than the threshold, higher than the threshold, greater than or equal to the threshold, less than the threshold, less than the threshold, lower than the threshold, less than or equal to the threshold, equal to the threshold, or the like.

[0052] As used herein, the term "component" should be interpreted generally to include hardware, firmware, or a combination of hardware and software. It is understood that systems and / or methods described herein may be implemented in various forms of hardware, firmware, or a combination of hardware and software. The actual specialized control hardware or specialized control software code used to implement these systems and / or methods does not limit the implementations. Thus, the operation and behavior of the systems and / or methods have been described herein without reference to specific software code; it is understood that software and hardware may be designed to implement the systems and / or methods based on the description herein.

[0053] Any of the processing components may be implemented as a central processing unit (CPU) or other processor that reads and executes a software program from a non-transitory computer-readable recording medium, such as a hard disk or a semiconductor storage device. For example, instructions may be executed by one or more processors, such as one or more CPUs, digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable logic arrays (FPGAs), programmable logic controllers (PLCs), or other equivalent integrated or discrete logic circuits.Accordingly, the term "processor" as used herein refers to any of the foregoing structures or any other structure suitable for implementing the techniques described herein. Software may be stored on a non-transitory computer-readable medium, such that the non-transitory computer-readable medium includes program code or a program algorithm stored thereon that, when executed, causes the processor, via a computer program, to perform the steps of a method.

[0054] A controller including hardware may also perform one or more of the techniques of this disclosure. A controller including one or more processors may use electrical signals and digital algorithms to perform its sensing, analysis, and control functions, which may further include correction functions. Such hardware, software, and firmware may be implemented within the same device or within separate devices to support the various techniques described in this disclosure.

[0055] A signal processing circuit and / or a signal conditioning circuit may receive one or more signals (e.g., measurement signals) from one or more components in the form of raw measurement data and may derive further information from the measurement signal. Signal conditioning, as used herein, refers to manipulating an analog signal in such a way that the signal meets the requirements of a next stage for further processing. Signal conditioning may include converting from analog to digital (e.g., via an analog-to-digital converter), amplifying, filtering, converting, biasing, ranging, isolation, and any other processes necessary to make a signal suitable for processing after conditioning.

[0056] Although certain combinations of features are recited in the claims and / or disclosed in the description, these combinations are not intended to limit the disclosure of implementations described herein. Many of these features may be combined in ways not expressly recited in the claims and / or disclosed in the description. For example, the disclosure includes each dependent claim in a claim set in combination with every other individual claim in that claim set and any combination of multiple claims in that claim set. As used herein, a phrase referring to "at least one of" a list of elements refers to any combination of those elements, including individual elements. As an example, "at least one of: a, b, or c" is intended to include a, b, c, a + b, a + c, b + c, and a + b + c, as well as any combination involving multiples of the same element (e.g.,a + a, a + a + a, a + a + b, a + a + c, a + b + b, a + c + c, b + b, b + b + b, b + b + c, c + c and c + c + c or any other order of a, b and c).

[0057] Furthermore, it should be understood that the disclosure of multiple steps or functions disclosed in the description or claims should not be construed as being in the specific order. Therefore, the disclosure of multiple steps or functions does not limit them to a particular order unless those steps or functions are not interchangeable for technical reasons. Furthermore, in some implementations, a single step may include or be broken into multiple sub-steps. Such sub-steps may be included and be part of the disclosure of that single step unless expressly excluded.

[0058] When "a component" or "one or more components" (or other element, such as "a controller" or "one or more controllers") is described or claimed (in a single claim or across multiple claims) as performing or being configured to perform multiple operations, such language is intended to broadly cover a variety of architectures and environments. Unless explicitly claimed otherwise (e.g.,beyond the use of "first component" and "second component" or other language distinguishing components in the claims), such language is intended to cover, for example, a single component that performs or is configured to perform all operations, a group of components that perform all operations together or are configured to perform all operations, a first component that performs or is configured to perform a first operation and a second component that performs or is configured to perform a second operation, or any combination of components that perform or are configured to perform the operations.For example, if a claim takes the form "one or more components configured to: perform X; perform Y; and perform Z", that claim should be interpreted to mean "one or more components configured to perform X; one or more (possibly different) components configured to perform Y; and one or more (also possibly different) components configured to perform Z".

[0059] No element, step, or instruction used herein should be construed as critical or essential unless expressly described as such. Further, the article "the," as used herein, is intended to include one or more elements referred to in connection with the article "the," and may be used interchangeably with "the one or more." In addition, the terms "comprises," "having," "comprising," or the like, as used herein, are intended to be open-ended terms that do not limit an element they modify (e.g., an element "comprising" A may also comprise B). Further, the phrase "based on" is intended to mean "based at least in part on," unless expressly stated otherwise. As used herein, the term "multiple" may be replaced with "a plurality of," and vice versa.In addition, the term “or,” as used herein, is intended to be inclusive when used in a series and may be used interchangeably with “and / or” unless expressly stated otherwise (e.g., when used in combination with “either” or “only one of”).

Claims

[1] A gas concentration sensor configured to measure a gas concentration of a target gas, comprising: a reference chamber configured to contain a reference gas; a measuring chamber configured to contain a target gas that is different from the reference gas; and a measuring circuit configurable in a calibration mode and an operating mode, the measuring circuit comprising: a full-bridge circuit comprising a first piezoresistive wire arranged in the reference chamber and exposed to the reference gas, a second piezoresistive wire arranged in the reference chamber and exposed to the reference gas, a third piezoresistive wire arranged in the measuring chamber and exposed to the target gas, and a fourth piezoresistive wire arranged in the measuring chamber and exposed to the target gas, wherein the full-bridge circuit is configured to receive an input voltage and generate a differential signal based on the input voltage, wherein during the calibration mode, the input voltage has a first voltage value at which the full-bridge circuit has negligible sensitivity to thermal conductivity, so that the difference signal is representative of an offset, wherein during the operating mode, the input voltage has a second voltage value at which the full-bridge circuit is sensitive to thermal conductivity with an operating sensitivity such that the difference signal is representative of a thermal conductivity of the target gas, wherein the measuring circuit is configured to measure the offset based on the difference signal during the calibration mode, and wherein the measuring circuit is configured to subtract the offset from the difference signal during the operating mode to generate a compensated difference signal. [2] The gas concentration sensor of claim 1, wherein during the operating mode, the compensated difference signal is a more accurate representation of the thermal conductivity of the target gas than the difference signal. [3] The gas concentration sensor according to claim 1 or 2, wherein the first voltage value is smaller than the second voltage value. [4] A gas concentration sensor according to any one of claims 1 to 3, wherein the negligible sensitivity to thermal conductivity is at least two orders of magnitude smaller than the operational sensitivity to thermal conductivity. [5] A gas concentration sensor according to any one of claims 1 to 4, wherein during the calibration mode the input voltage causes the first piezoresistive wire, the second piezoresistive wire, the third piezoresistive wire and the fourth piezoresistive wire to experience a negligible temperature change such that the difference signal is a measure of at least one offset effect. [6] The gas concentration sensor of claim 5, wherein the at least one offset effect includes at least one of pressure, temperature, production variation, or lifetime drift. [7] The gas concentration sensor of claim 5 or 6, wherein during the operating mode, the input voltage causes the first piezoresistive wire and the second piezoresistive wire to experience a first temperature increase based on a first rate of thermal release to the reference gas, and wherein during the operating mode, the input voltage causes the third piezoresistive wire and the fourth piezoresistive wire to experience a second temperature increase based on a second rate of thermal release to the target gas. [8] A gas concentration sensor according to any one of claims 1 to 7, wherein the measuring circuit further comprises: a subtraction component configured to receive the difference signal, wherein the subtraction component is configured to output the difference signal during the calibration mode, and wherein the subtraction component is configured to subtract the offset from the difference signal during the operating mode to generate the compensated difference signal. [9] A gas concentration sensor according to claim 8, wherein the measuring circuit further comprises: an analog-to-digital converter (ADC) coupled to an output of the subtraction component, the ADC configured to generate a digital signal based on the difference signal during the calibration mode; a scaler configured to upscale the digital signal by a scaling factor during the calibration mode to generate a scaled digital signal equal to the offset, wherein the scaling factor is equal to a ratio of the second voltage value to the first voltage value; and a digital-to-analog converter (DAC) configured to receive the scaled digital signal and generate an analog offset signal based on the scaled digital signal. [10] The gas concentration sensor of claim 9, wherein the DAC is configured to provide the analog offset signal to the subtraction component during the operating mode, and wherein the subtraction component is configured to subtract the analog offset signal from the difference signal during the operating mode to generate the compensated difference signal. [11] The gas concentration sensor of claim 9, wherein the ADC is configured to convert the compensated difference signal into a digital measurement signal representative of the thermal conductivity of the target gas during the operating mode. [12] A gas concentration sensor configured to measure a gas concentration of a target gas, comprising: a reference chamber configured to contain a reference gas; a measuring chamber configured to contain the target gas that is different from the reference gas; and a measuring circuit configurable in a calibration mode and an operating mode, the measuring circuit comprising: a resistance bridge circuit comprising a plurality of resistance elements, including at least one first resistance element arranged in the reference chamber and at least one second resistance element arranged in the measuring chamber, wherein the resistance bridge circuit is configured to receive an input voltage and generate a measurement signal based on the input voltage, wherein during the calibration mode, the input voltage has a first voltage value at which the resistance bridge circuit has a negligible sensitivity to thermal conductivity, so that the measurement signal is representative of an offset, wherein during the operating mode, the input voltage has a second voltage value at which the resistance bridge circuit is sensitive to thermal conductivity with an operating sensitivity such that the measurement signal is representative of a thermal conductivity of the target gas, wherein the measuring circuit is configured to measure the offset based on the measurement signal during the calibration mode, and wherein the measuring circuit is configured to subtract the offset from the measuring signal during the operating mode to generate a compensated measuring signal. [13] A gas concentration sensor according to claim 12, wherein during the operating mode the compensated measurement signal is a more accurate representation of the thermal conductivity of the target gas than the measurement signal. [14] A gas concentration sensor according to claim 12 or 13, wherein the first voltage value is smaller than the second voltage value. [15] A gas concentration sensor according to any one of claims 12 to 14, wherein the negligible sensitivity to thermal conductivity is at least two orders of magnitude smaller than the operating sensitivity to thermal conductivity. [16] The gas concentration sensor of any one of claims 12 to 15, wherein during the calibration mode, the input voltage causes the at least one first resistive element to experience a first change in resistance based on at least one offset effect, and wherein during the calibration mode, the input voltage causes the at least one second resistive element to experience a second change in resistance based on the at least one offset effect. [17] The gas concentration sensor of claim 16, wherein during the operating mode, the input voltage causes the at least one first resistive element to experience a third change in resistance based on a first thermal interaction of the at least one first resistive element with the reference gas, and wherein during the operating mode, the input voltage causes the at least one second resistive element to experience a fourth change in resistance based on a second thermal interaction of the at least one second resistive element with the target gas. [18] The gas concentration sensor of claim 16 or 17, wherein during the operating mode, the input voltage causes the at least one first resistive element to experience a third change in resistance based on a thermal conductivity of the reference gas, and wherein during the operating mode, the input voltage causes the at least one second resistive element to experience a fourth change in resistance based on the thermal conductivity of the target gas. [19] A method for calibrating an offset of a gas concentration sensor, the method comprising: Configuring a measuring circuit of the gas concentration sensor in a calibration mode; Applying, during the calibration mode, a first input voltage to a resistive bridge circuit of the gas concentration sensor to cause the resistive bridge circuit to generate a first measurement signal, wherein based on the first input voltage, the resistive bridge circuit has negligible sensitivity to thermal conductivity such that the first measurement signal is representative of the offset; Configuring, during the calibration mode, a compensation component of the measurement circuit with the offset derived from the first measurement signal; Configuring the measuring circuit of the gas concentration sensor in an operating mode; Applying, during the operating mode, a second input voltage to the resistive bridge circuit of the gas concentration sensor to cause the resistive bridge circuit to generate a second measurement signal, wherein the second input voltage is greater than the first input voltage, and wherein, based on the second input voltage, the resistive bridge circuit is sensitive to thermal conductivity with an operating sensitivity such that the second measurement signal is representative of a thermal conductivity of a measurement gas; and Subtracting, during the operating mode, the offset configured on the compensation component from the second measurement signal to generate a compensated measurement signal. [20] The method of claim 19, wherein the negligible sensitivity to thermal conductivity is at least two orders of magnitude smaller than the operating sensitivity to thermal conductivity.

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