Temperature compensation circuit and method for a pressure sensor with a temperature profile that is a broken line

Abstract

The application provides a temperature compensation circuit and method for a pressure sensor with a temperature curve in the shape of a broken line, the pressure sensor comprising a pressure-sensitive core, and the sensitivity of which changes in the shape of a broken line with temperature change, so that the temperature curve has a turning point, the temperature compensation circuit comprising an NTC resistor and a PTC resistor, the NTC resistor and the PTC resistor being connected in parallel to form an NTC / PTC resistor network, and being connected in series between a power input and an input end of a Wheatstone bridge of the pressure-sensitive core. The application is mainly used for compensating the temperature drift of the pressure sensor with the sensitivity of the pressure core increasing first and then decreasing with temperature change, so as to meet the technical index requirements.

Description

[Technical Field]

[0001] This invention relates to the field of temperature compensation for pressure sensors, and in particular to a temperature compensation circuit and method for a pressure sensor whose sensitivity varies linearly with temperature. [Background Technology]

[0002] Currently, the existing pressure sensor temperature compensation methods on the market are mainly divided into two types: analog compensation and digital compensation. Digital compensation is calibrated through a signal conditioning chip, and the output voltage is usually in the volt (V) range. Analog compensation mainly achieves temperature compensation of the pressure sensor through an external resistor network or amplification circuit, and its output voltage is usually in the volt (V) or millivolt (mV) range.

[0003] In most pressure sensors, the sensitivity change of the pressure core exhibits a negative correlation with temperature changes, and temperature compensation is typically achieved by connecting an external NTC resistor network in series. However, for some pressure cores where the sensitivity change is not negatively correlated with temperature changes, the compensation method is not entirely applicable. For example, the sensitivity of the pressure core in a pressure sensor typically decreases monotonically with increasing temperature; temperature drift can be compensated for by connecting an external NTC resistor network in series with the sensor.

[0004] As those skilled in the art know, pressure sensors use a pressure core as the pressure-sensing element, and its core component is called a pressure-sensitive chip. The pressure-sensitive chip is designed based on the piezoresistive effect of semiconductors. The piezoresistive effect of semiconductors refers to the change in resistivity (or conductivity) of a semiconductor material when an external force is applied. When the supply voltage is constant, the output voltage of the Wheatstone bridge of the pressure core mainly depends on the resistance values ​​of the four bridge arms, changing with the change in bridge arm resistance. Based on this characteristic of the bridge, by changing the resistance values ​​of the bridge arms through an external circuit, the output voltage can meet the performance requirements, thus compensating for the pressure sensor. The four bridge arm resistors are made of semiconductor material, and their trends of temperature change are the same, but the magnitude of the change is inconsistent, i.e., the temperature drift coefficients are different, resulting in different zero-point outputs at different temperatures, causing temperature drift in the zero-point output. To ensure that the zero-point output of the bridge is 0mV across all temperatures, existing technologies typically use high-precision, low-temperature-drift fixed resistors connected in series / parallel on the bridge arms to compensate for the zero-point output voltage. The temperature drift characteristic curve of the full-scale output voltage of the pressure core is the full-scale output voltage V. out It decreases with increasing temperature, therefore it can be solved by constructing a U that increases with increasing temperature. in To offset the full-scale output voltage V out The change in V outThe output remains constant across the entire temperature range. Currently, the industry primarily utilizes compensation circuits constructed with NTC thermistor networks and diode networks. Specifically, an NTC resistor network is connected in series externally as a voltage divider network R. Then, by calculating compensation parameters, the required values ​​of the voltage divider network R at various temperatures can be determined, resulting in the temperature curve of R. Based on the characteristics of the R curve, a thermistor with a negative temperature coefficient is selected to fit the temperature curve of R. This ensures that the output voltage performance requirements are met at both the zero-point and full-scale ranges.

[0005] However, for some pressure cores made of silicon strain gauges, such as Figure 1 As shown, its sensitivity does not decrease monotonically with increasing temperature, but rather increases first and then decreases with increasing temperature, making existing compensation methods inapplicable. [Summary of the Invention]

[0006] Therefore, the technical problem to be solved by the present invention is to provide a temperature compensation circuit and compensation method for a pressure sensor with a broken temperature curve, which is mainly used to compensate for the temperature drift of the pressure sensor, where the sensitivity of the pressure core first increases and then decreases with temperature change, so as to meet the technical specifications.

[0007] To achieve the aforementioned first objective of the present invention, the technical solution adopted in the embodiments of the present invention is: a temperature compensation circuit for a pressure sensor with a broken-line temperature curve, wherein the pressure sensor includes a pressure-sensitive core, and the sensitivity changes with temperature in a broken-line manner, so that the temperature curve has an inflection point; the temperature compensation circuit includes an NTC resistor and a PTC resistor, wherein the NTC resistor and the PTC resistor are connected in parallel to form an NTC / PTC resistor network, and are connected in series between the power input and the input terminal of the Wheatstone bridge of the pressure-sensitive core;

[0008] When the temperature of the pressure sensor is lower than the inflection point temperature of the temperature curve of the NTC / PTC resistor network, the trend of the resistor network change mainly depends on the PTC resistor, and the resistance value of the resistor network increases with temperature.

[0009] When the temperature of the pressure sensor is higher than the inflection point temperature of the temperature curve of the NTC / PTC resistor network, the trend of the resistor network change mainly depends on the NTC resistor. At this time, the resistance value of the resistor network decreases with temperature, thus realizing the trend of the resistor network changing in a broken line.

[0010] Furthermore, the NTC / PTC resistor network also includes a parallel fixed resistor, which is connected in parallel with the NTC resistor and the PTC resistor.

[0011] To achieve the aforementioned second objective of the present invention, the technical solution adopted in the embodiments of the present invention is: a temperature compensation method for a pressure sensor with a piecewise linear temperature curve, characterized in that: a temperature compensation circuit is used to implement the aforementioned first objective; and includes the following steps:

[0012] S1. Collect the resistance values ​​of each arm of the Wheatstone bridge of the pressure sensor to be compensated at different temperatures.

[0013] S2. Calculate the resistance curve required to compensate the pressure-sensitive core based on the resistance values ​​collected at different temperatures in step S1.

[0014] S3. Select NTC and PTC resistors with appropriate resistance values ​​according to the characteristics of the resistance curve to fit the required resistance curve. Connect the NTC and PTC resistors in parallel to form an NTC / PTC resistor network. Then, combine them with a parallel fixed resistor to make the NTC / PTC resistor network change with temperature in a broken line shape.

[0015] S4. During temperature compensation, the following controls are implemented:

[0016] When the temperature of the pressure sensor is lower than the inflection point temperature of the temperature curve of the NTC / PTC resistor network, the trend of the resistor network change mainly depends on the PTC resistor, and the resistance value of the resistor network increases with temperature.

[0017] When the temperature of the pressure sensor is higher than the inflection point temperature of the temperature curve of the NTC / PTC resistor network, the trend of the resistor network change mainly depends on the NTC resistor. At this time, the resistance value of the resistor network decreases with temperature, thus realizing the trend of the resistor network changing in a broken line.

[0018] Furthermore, step S2 specifically involves:

[0019] S21. Based on the resistance values ​​of each arm of the Wheatstone bridge at different temperatures obtained in step S1, the output voltage of the pressure sensor at different temperatures is calculated.

[0020] S22. Assuming a voltage divider resistor network is connected in series between the power input and the arms of the Wheatstone bridge to divide the supply voltage of the Wheatstone bridge, the resistance value of the voltage divider resistor network is the resistance value required for compensation. Calculate the full-scale output voltage using Formula 1 as V. out The corresponding Wheatstone bridge supply voltage U in :

[0021]

[0022] In formula 1:

[0023] V—Power supply voltage, which is a known value;

[0024] V out —Full-scale output voltage, which is the target value;

[0025] V FS —The full-scale output voltage of the pressure-sensitive core at each temperature is calculated using resistance;

[0026] U in —Full-scale output voltage is V out The corresponding Wheatstone bridge supply voltage at that time is the value obtained from Formula 1;

[0027] When the output voltage V at each temperature FS Substitute each U into Formula 1 to calculate each U in , get U in Temperature variation curve;

[0028] S23. Construct a U in To compensate for the full-scale output voltage, we need to find the voltage divider voltage U of the voltage divider resistor network. Then:

[0029] U = Vcc - U in Formula 2;

[0030] In formula 2:

[0031] Vcc—Product power supply voltage;

[0032] U in —Full-scale output voltage is V FS The corresponding bridge supply voltage is obtained using Formula 1;

[0033] S24. If the voltage divider resistor network and the Wheatstone bridge arms are connected in series and the current I is the same, then the voltage ratio is equal to the resistance ratio. Therefore:

[0034]

[0035] In formula 3:

[0036] U—the voltage divided by the voltage divider resistor network;

[0037] U in —Full-scale output voltage is V FS The corresponding Wheatstone bridge supply voltage at that time

[0038] R B —The equivalent resistance of the Wheatstone bridge arm is calculated from the resistance data;

[0039] R—the resistance value of the voltage divider network, which is the value obtained from formula 3;

[0040] By calculating the required values ​​of the voltage divider resistor network R at various temperatures, the temperature curve of R is obtained. This temperature curve of R is the resistance curve required to compensate for the pressure-sensitive core.

[0041] The advantages of this invention are as follows: An NTC resistor and a PTC resistor are connected in parallel to form an NTC / PTC resistor network, which is then connected in series between the power input and the input terminal of the Wheatstone bridge of the pressure-sensitive core. When the pressure sensor temperature is low, the resistance of the NTC / PTC resistor network increases with temperature through the PTC resistor; when the pressure sensor temperature is high, the resistance of the NTC / PTC resistor network decreases with temperature through the NTC resistor. This achieves a zigzag trend in the resistor network, thereby accurately fitting the temperature characteristic curve required by the pressure core and compensating for the temperature drift of the pressure sensor, where the sensitivity of the pressure core first increases and then decreases with temperature changes, thus meeting the technical specifications. [Attached Image Description]

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] Figure 1 This is a schematic diagram of the full-scale output curve of a pressure core made of silicon strain gauge as a function of temperature.

[0044] Figure 2 A schematic diagram of the equivalent circuit of a pressure sensor chip using a Wheatstone bridge.

[0045] Figure 3 This is the resistance curve calculated by the present invention to compensate for the pressure-sensitive core;

[0046] Figure 4 This is the curve showing the change in PTC resistance with temperature according to the present invention;

[0047] Figure 5 This is the temperature-dependent trend curve of the NTC resistor of this invention;

[0048] Figure 6 This is the temperature-dependent trend curve of the NTC / PTC resistor network of this invention;

[0049] Figure 7 This is a block diagram illustrating the principle structure of the temperature compensation circuit of this invention;

[0050] Figure 8 This is a circuit diagram of the temperature compensation circuit of the present invention;

[0051] Figure 9 This is a flowchart of the temperature compensation method of the present invention;

[0052] Figure 10 This is a schematic diagram of a temperature compensation fitting curve according to an embodiment of the present invention;

[0053] Figure 11 This is a schematic diagram of the circuit structure of a temperature compensation circuit according to an embodiment of the present invention;

[0054] Figure 12 This is a schematic diagram of the fitted resistor network curve and the required voltage divider resistor network curve according to an embodiment of the present invention.

Detailed Implementation Methods

[0055] This invention provides a temperature compensation circuit and method for a pressure sensor with a broken-line temperature curve. It is mainly used to compensate for the temperature drift of the pressure sensor, where the sensitivity of the pressure core first increases and then decreases with temperature changes, so that the sensor meets the technical specifications.

[0056] The technical solution in the embodiments of the invention is to solve the above problems. The general idea is as follows: NTC resistors and PTC resistors are connected in parallel to form an NTC / PTC resistor network, and connected in series between the power input and the input terminal of the Wheatstone bridge of the pressure sensing core. When the temperature of the pressure sensor is low, the resistance of the NTC / PTC resistor network increases with temperature through the PTC resistor; when the temperature of the pressure sensor is high, the resistance of the NTC / PTC resistor network decreases with temperature through the NTC resistor. This achieves a trend of zigzag change in the resistor network, thereby accurately fitting the temperature characteristic curve required by the pressure core.

[0057] To better understand the above technical solution, the compensation principle of the present invention will be explained below:

[0058] 1. First, it is necessary to understand the characteristics of the output voltage of the Wheatstone bridge.

[0059] The pressure sensor chip has four semiconductor silicon strain gauges on its surface, which are used to convert the pressure changes sensed by the chip into electrical signals for output. For example... Figure 2 As shown, it is equivalent to four resistors that change with pressure connected in a bridge configuration, i.e., a Wheatstone bridge. The output of the Wheatstone bridge circuit is differential, and the output voltage can be expressed as:

[0060]

[0061]

[0062]

[0063] In the formula:

[0064] U in The supply voltage for the Wheatstone bridge;

[0065] R1, R2, R3 and R4 are the resistance values ​​of the four silicon strain gauges of the bridge circuit, hereinafter referred to as bridge arm resistors;

[0066] V out+ This is the voltage between bridge arms R2 and R3;

[0067] V out- This is the voltage between bridge arms R1 and R4;

[0068] V out This is the differential output voltage of the bridge;

[0069] R1 and R3 are located diagonally opposite each other in the bridge circuit, and their resistance increases with increasing pressure. R2 and R4 are also located diagonally opposite each other, and their resistance decreases with increasing pressure. in When the pressure is constant, R3 increases, R2 decreases, and V... out+ Increase; R1 increases, R4 decreases, V out- Decrease, output voltage V out Increase. Conversely, when the pressure decreases, V out The supply voltage U decreases. in When constant, the output voltage of a Wheatstone bridge primarily depends on the resistance values ​​of its four bridge arms, changing with the resistance of the bridge arms. Based on this characteristic of the bridge, by simply changing the resistance values ​​of the bridge arms through an external circuit, the output voltage can be adjusted to meet performance requirements, thus compensating for the pressure sensor.

[0070] 2. Zero-point output voltage and temperature drift compensation

[0071] The four bridge arm resistors on the pressure-sensitive chip are made of semiconductor material. Their temperature change trends are the same, but the magnitude of the change is inconsistent, that is, the temperature drift coefficients are different. This results in the zero-point output being different at different temperatures, and the zero-point output will experience temperature drift. When the following relationship (4) holds, the zero-point temperature drift is 0.

[0072] α1+α2=α3+α4 (4)

[0073] In equation (4), α1 to α4 are the temperature drift coefficients of the four arms of the Wheatstone bridge. When the temperature drift coefficients of the four arms are the same, the bridge output is equal at all temperatures, which is a specific value. At the same time, the resistance values ​​of the four arms cannot be completely the same. According to equation (3), the output voltage V out The zero-point output voltage V is not zero when the following relationship (5) holds. out It is 0mV.

[0074] R1 + R2 = R3 + R4 (5)

[0075] When equations (4) and (5) are both true, the zero-point output of the Wheatstone bridge is 0mV at all temperatures. The zero-point output voltage can be compensated by connecting high-precision, low-temperature drift fixed resistors in series / parallel on the bridge arms. This invention achieves this by using a series NTC / PTC resistor network in the circuit for voltage division. By calculating the required value of the voltage divider resistor network R at various temperatures, the temperature curve of R is obtained. Based on the characteristics of the resistance curve, suitable NTC and PTC resistors are selected to fit the required resistance curve, i.e., the resistance curve required to compensate for the pressure-sensitive core, such as... Figure 3 As shown.

[0076] 3. The individual curves of NTC and PTC resistors, and the temperature variation trend of the NTC and PTC combination. The temperature variation trend of PTC is as follows: Figure 4 As shown; the trend of NTC variation with temperature is as follows: Figure 5 As shown; the temperature variation trend of the NTC and PTC combination is as follows. Figure 6 As shown.

[0077] Example 1

[0078] Please see Figure 7 and Figure 8 As shown, this embodiment provides a temperature compensation circuit for a pressure sensor with a broken-line temperature curve. The pressure sensor includes a pressure-sensitive core, and its sensitivity changes with temperature in a broken-line manner, giving the temperature curve an inflection point. The temperature compensation circuit includes an NTC resistor and a PTC resistor. The NTC resistor and the PTC resistor are connected in parallel between the power input and the input terminal of the Wheatstone bridge of the pressure-sensitive core to form an NTC / PTC resistor network.

[0079] When the temperature of the pressure sensor is lower than the inflection point temperature of the temperature curve of the NTC / PTC resistor network, the trend of the resistor network change mainly depends on the PTC resistor, and the resistance value of the resistor network increases with temperature.

[0080] When the temperature of the pressure sensor is higher than the inflection point temperature of the temperature curve of the NTC / PTC resistor network, the trend of the resistor network change mainly depends on the NTC resistor. At this time, the resistance value of the resistor network decreases with temperature, thus realizing the trend of the resistor network changing in a broken line.

[0081] Furthermore, the NTC / PTC resistor network also includes an external electrical group, which is connected in parallel with the NTC resistor and the PTC resistor.

[0082] Example 2

[0083] Please see Figure 9As shown, this embodiment provides a temperature compensation method for a pressure sensor with a piecewise linear temperature curve, used to achieve the aforementioned first objective of the temperature compensation circuit; and includes the following steps:

[0084] S1. Collect the resistance values ​​of each arm of the Wheatstone bridge of the pressure sensor to be compensated at different temperatures.

[0085] S2, such as Figure 3 As shown, the resistance curve required to compensate the pressure-sensitive core is calculated based on the resistance values ​​collected in step S1 at different temperatures; the resistance curve required to compensate the pressure-sensitive core is a voltage divider resistance curve.

[0086] S3. Based on the characteristics of the resistance curve, select NTC and PTC resistors with appropriate resistance values ​​to fit the required resistance curve. Connect the NTC and PTC resistors in parallel to form an NTC / PTC resistor network. Further adjust the slope of the NTC / PTC resistor network curve by connecting a fixed resistor in parallel, adjusting the curve slope to coincide as closely as possible with the resistance-temperature curve required by the pressure-sensitive core. The resistance value of the fixed resistor in parallel is determined by the required resistance curve, so that the NTC / PTC resistor network changes with temperature in a piecewise linear pattern as required for compensation.

[0087] like Figure 10 As shown, the temperature compensation fitting curves are shown. The solid line is the resistance-temperature curve that needs to be fitted, and the dashed line is the resistance-temperature curve fitted by the scheme of the present invention.

[0088] S4. During temperature compensation, the following controls are implemented:

[0089] like Figure 8 As shown, when the temperature of the pressure sensor is lower than the inflection point temperature of the temperature curve of the NTC / PTC resistor network, the trend of the resistor network change mainly depends on the PTC resistor, and the resistance of the resistor network increases with temperature.

[0090] like Figure 9 As shown, when the temperature of the pressure sensor is higher than the inflection point temperature of the temperature curve of the NTC / PTC resistor network, the trend of the resistor network change mainly depends on the NTC resistor. At this time, the resistance of the resistor network decreases with temperature.

[0091] Ultimately Figure 10 As shown, this is used to achieve a resistor network that exhibits a zigzag pattern.

[0092] Specifically, step S2 is as follows:

[0093] S21. Based on the resistance values ​​of each arm of the Wheatstone bridge at different temperatures obtained in step S1, the output voltage of the pressure sensor at different temperatures is calculated.

[0094] S22. Assuming a voltage divider resistor network is connected in series between the power input and the arms of the Wheatstone bridge to divide the supply voltage of the Wheatstone bridge, the resistance value of the voltage divider resistor network is the resistance value required for compensation. Calculate the full-scale output voltage using Formula 1 as V. out The corresponding Wheatstone bridge supply voltage U in :

[0095]

[0096] In formula 1:

[0097] V—Power supply voltage, which is a known value;

[0098] V out —Full-scale output voltage, which is the target value, usually specified by the technical agreement or development task book;

[0099] V FS —The full-scale output voltage of the pressure-sensitive core at each temperature is calculated using resistance;

[0100] U in —Full-scale output voltage is V out The corresponding Wheatstone bridge supply voltage at that time is the value obtained from Formula 1;

[0101] When the output voltage V at each temperature FS Substitute each U into Formula 1 to calculate each U in , get U in Temperature variation curve;

[0102] S23, Construction U in To compensate for the full-scale output voltage, we need to find the voltage divider voltage U of the voltage divider resistor network. Then:

[0103] U = Vcc - U in Formula 2;

[0104] In formula 2:

[0105] Vcc—Product power supply voltage;

[0106] U in —Full-scale output voltage is V FS The corresponding bridge supply voltage is obtained using Formula 1;

[0107] S24. If the voltage divider resistor network and the Wheatstone bridge arms are connected in series and the current I is the same, then the voltage ratio is equal to the resistance ratio. Therefore:

[0108]

[0109] In formula 3:

[0110] U—the voltage divided by the voltage divider resistor network;

[0111] U in —Full-scale output voltage is V FS The corresponding Wheatstone bridge supply voltage at that time

[0112] R B —The equivalent resistance of the Wheatstone bridge arm is calculated from the resistance data;

[0113] R—the resistance value of the voltage divider network, which is the value obtained from formula 3;

[0114] By calculating the required values ​​of the voltage divider resistor network R at various temperatures, the temperature curve of R is obtained. This temperature curve of R is the resistance curve required to compensate for the pressure-sensitive core.

[0115] Compensation Case: This case illustrates the compensation data for the applicant's CYYZ351V-200 pressure sensor.

[0116] like Figure 11 As shown, R1 to R4 are the bridge arm resistors of the Wheatstone bridge in the equivalent circuit of the pressure core. The NTC / PTC resistor network includes resistors RN, RP, and R5, where RN is an NTC thermistor, RP is a PTC thermistor, and R5 is a parallel fixed resistor connected in parallel with RN and RP. The calculated values ​​(based on compensation data from our CYYZ351V-200 pressure sensor) are shown in Table 1. The fitted resistor network curve and the required voltage divider resistor network curve are shown below. Figure 12 As shown, the solid line represents the resistance-temperature curve to be fitted, and the dashed line represents the resistance-temperature curve that can be fitted by the present invention.

[0117] Table 1. Resistance values ​​for each component.

[0118] Position RN RP R1 R2 R3 R4 R5 Resistance (KΩ) 1 15 2.41 2.394 2.540 2.561 100

[0119] The data before and after compensation are shown in Tables 2 and 3, respectively.

[0120] Table 2. Test data of pressure sensor before compensation (5VDC test)

[0121] temperature 0kPa 280kPa 560kPa 840kPa 1120kPa 1400kPa Sensitivity -55 -2.4 22.88 48.16 73.44 98.72 124 126.4 25 2 31.2 60.4 89.6 118.8 148 146 125 9.3 27.38 45.46 63.54 81.62 99.7 90.4

[0122] Table 3 Test data of pressure sensor after compensation (10VDC test, required output of 0~100mV, sensitivity of 100±1mV)

[0123]

[0124]

[0125] The test data of the pressure sensor before and after compensation in the above compensation case show that the sensitivity of the pressure sensor before compensation first increases and then decreases with increasing temperature, and the sensitivity does not meet the requirement of 100±1mV. The NTC / PTC resistor network of this invention can accurately fit the resistance-temperature characteristic curve required for such pressure sensor compensation, thus compensating the sensitivity of the pressure sensor to the required range.

[0126] The advantages of this invention are as follows: An NTC resistor and a PTC resistor are connected in parallel to form an NTC / PTC resistor network, which is then connected in series between the power input and the input terminal of the Wheatstone bridge of the pressure-sensitive core. When the pressure sensor temperature is low, the resistance of the NTC / PTC resistor network increases with temperature through the PTC resistor; when the pressure sensor temperature is high, the resistance of the NTC / PTC resistor network decreases with temperature through the NTC resistor. This achieves a zigzag trend in the resistor network, thereby accurately fitting the temperature characteristic curve required by the pressure core and compensating for the temperature drift of the pressure sensor, where the sensitivity of the pressure core first increases and then decreases with temperature changes, thus meeting the technical specifications.

[0127] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A temperature compensation circuit for a pressure sensor with a piecewise linear temperature curve, wherein the pressure sensor includes a pressure-sensitive core, and its sensitivity changes linearly with temperature, resulting in an inflection point in the temperature curve, characterized in that: The temperature compensation circuit includes an NTC resistor and a PTC resistor. The NTC resistor and the PTC resistor are connected in parallel to form an NTC / PTC resistor network, and are connected in series between the power input and the input terminal of the Wheatstone bridge of the pressure-sensitive core. When the temperature of the pressure sensor is lower than the inflection point temperature of the temperature curve of the NTC / PTC resistor network, the trend of the resistor network change mainly depends on the PTC resistor, and the resistance value of the resistor network increases with temperature. When the temperature of the pressure sensor is higher than the inflection point temperature of the temperature curve of the NTC / PTC resistor network, the trend of the resistor network change mainly depends on the NTC resistor. At this time, the resistance value of the resistor network decreases with temperature, thus realizing the trend of the resistor network changing in a broken line.

2. The temperature compensation circuit for a pressure sensor with a piecewise linear temperature curve as described in claim 1, characterized in that: The NTC / PTC resistor network also includes a parallel fixed resistor, which is connected in parallel with the NTC resistor and the PTC resistor.

3. A temperature compensation method for a pressure sensor with a piecewise linear temperature curve, characterized in that: For implementing the temperature compensation circuit as claimed in claim 1 or 2; and comprising the following steps: S1. Collect the resistance values ​​of each arm of the Wheatstone bridge of the pressure sensor to be compensated at different temperatures. S2. Calculate the resistance curve required to compensate the pressure-sensitive core based on the resistance values ​​collected at different temperatures in step S1. S3. Select NTC and PTC resistors with appropriate resistance values ​​according to the characteristics of the resistance curve to fit the required resistance curve. Connect the NTC and PTC resistors in parallel to form an NTC / PTC resistor network. Then, combine them with a parallel fixed resistor to make the NTC / PTC resistor network change with temperature in a broken line shape. S4. During temperature compensation, the following controls are implemented: When the temperature of the pressure sensor is lower than the inflection point temperature of the temperature curve of the NTC / PTC resistor network, the trend of the resistor network change mainly depends on the PTC resistor, and the resistance value of the resistor network increases with temperature. When the temperature of the pressure sensor is higher than the inflection point temperature of the temperature curve of the NTC / PTC resistor network, the trend of the resistor network change mainly depends on the NTC resistor. At this time, the resistance value of the resistor network decreases with temperature, thus realizing the trend of the resistor network changing in a broken line.

4. The temperature compensation method for a pressure sensor with a piecewise linear temperature curve as described in claim 3, characterized in that: Specifically, step S2 is as follows: S21. Based on the resistance values ​​of each arm of the Wheatstone bridge at different temperatures obtained in step S1, the output voltage of the pressure sensor at different temperatures is calculated. S22. Assuming a voltage divider resistor network is connected in series between the power input and the arms of the Wheatstone bridge to divide the supply voltage of the Wheatstone bridge, the resistance value of the voltage divider resistor network is the resistance value required for compensation. Calculate the full-scale output voltage using Formula 1 as V. out The corresponding Wheatstone bridge supply voltage U in : In formula 1: V—Power supply voltage, which is a known value; V out —Full-scale output voltage, which is the target value; V FS —The full-scale output voltage of the pressure-sensitive core at each temperature is calculated using resistance; U in —Full-scale output voltage is V out The corresponding Wheatstone bridge supply voltage at that time is the value obtained from Formula 1; When the output voltage V at each temperature FS Substitute each U into Formula 1 to calculate each U in , get U in Temperature variation curve; S23, Construction U in To compensate for the full-scale output voltage, we need to find the voltage divider voltage U of the voltage divider resistor network. Then: U = Vcc - U in Formula 2; In formula 2: Vcc—Product power supply voltage; U in —Full-scale output voltage is V FS The corresponding bridge supply voltage is obtained using Formula 1; S24. If the voltage divider resistor network and the Wheatstone bridge arms are connected in series and the current I is the same, then the voltage ratio is equal to the resistance ratio. Therefore: In formula 3: U—the voltage divided by the voltage divider resistor network; U in —Full-scale output voltage is V FS The corresponding Wheatstone bridge supply voltage at that time R B —The equivalent resistance of the Wheatstone bridge arm is calculated from the resistance data; R—the resistance value of the voltage divider network, which is the value obtained from formula 3; By calculating the required values ​​of the voltage divider resistor network R at various temperatures, the temperature curve of R is obtained. This temperature curve of R is the resistance curve required to compensate for the pressure-sensitive core.

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