Pressure and temperature cooperative measurement method of piezoresistive MEMS pressure sensor

Abstract

The invention provides a pressure and temperature cooperative measurement method for a piezoresistive MEMS pressure sensor, and the method comprises the following steps: S1, switching a resistor connection mode of an MEMS header of the piezoresistive MEMS pressure sensor through an MOS switch, and obtaining pressure and temperature signals in a time-sharing manner; s2, eliminating the influence of pressure on temperature measurement by using the equivalent resistance Req; and S3, based on the pre-stored temperature-pressure characteristic curve, compensating the temperature drift error in real time through a digital algorithm. According to the invention, cooperative measurement of pressure and temperature is realized by using a piezoresistive MEMS sensor gauge head piezoresistor, and calibration and compensation of temperature and pressure are realized through a digital algorithm; the design difficulty and process requirements of the piezoresistive temperature and pressure integrated sensor chip on the piezoresistive MEMS sensor header and the signal conditioning circuit are reduced, the measurement precision of temperature and pressure is improved, and the development and manufacturing cost of the piezoresistive temperature and pressure integrated sensor chip is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit design, and in particular to a pressure-temperature coordinated measurement method of a piezoresistive MEMS pressure sensor. Background Art

[0002] In existing technologies, MEMS piezoresistive pressure sensors often use complex mechanical structures (such as double-sided bonded sandwich structures) or additional temperature-sensitive elements (such as thermocouples and thermistors) to achieve coordinated temperature and pressure measurement, leading to the following problems:

[0003] 1. Cross-sensitivity and temperature drift: Temperature and pressure measurements can affect each other, a phenomenon known as cross-sensitivity, which can lead to inaccurate measurement results. Some integrated sensors suppress crosstalk in dual-parameter measurements by constructing new spatially orthogonal temperature-pressure integrated sensing mechanisms, such as integrating "in-plane thermoelectrics" and "out-of-plane piezoresistors." Others use structural design to isolate the operating temperature of the temperature-sensitive element and the pressure-sensitive element from each other, keeping both within their optimal operating temperature range. If the optimal operating temperature ranges of the pressure-sensitive element and the temperature-sensitive element are inconsistent, the temperature-sensitive element will function normally, but the pressure-sensitive element may experience severe temperature drift or even fail. Currently, some sensors are addressing this issue by increasing the contact surface and heat transfer efficiency between the temperature-sensitive element and the measured medium, reducing the contact surface and heat transfer efficiency between the pressure-sensitive element and the measured medium, providing appropriate thermal isolation between the temperature-sensitive element and other components, and providing thermal compensation for the pressure-sensitive element. Because the resistance of varistors is significantly affected by temperature, traditional hardware compensation methods require the addition of thermal isolation structures or complex conditioning circuits, which are costly to manufacture and difficult to miniaturize.

[0004] 2. High process complexity: For example, a two-step bonding process is used to prepare a cavity structure. Although it reduces the risk of wafer breakage, it requires the temporary bonding sheet to be bonded to the substrate twice, and the process steps are cumbersome. Alternatively, the sensitivity can be improved through a peninsula groove structure, but a special layout of the varistor is required, and the process tolerance is low.

[0005] 3. Complex signal processing: Using a multi-material array to establish a set of equations to decouple temperature and pressure, but it requires multiple sets of detection materials, is difficult to integrate, and relies on high-precision algorithms. Summary of the Invention

[0006] To solve the above problems, the present invention aims to propose a pressure-temperature coordinated measurement method for a piezoresistive MEMS pressure sensor, which utilizes the piezoresistive resistor of the piezoresistive MEMS sensor head to realize the coordinated measurement of pressure and temperature, and realizes the calibration and compensation of temperature and pressure through a digital algorithm; reduces the design difficulty and process requirements of the piezoresistive MEMS sensor head and signal conditioning circuit of the piezoresistive temperature and pressure integrated sensor chip, improves the measurement accuracy of temperature and pressure, and reduces the development and manufacturing costs of the piezoresistive temperature and pressure integrated sensor chip.

[0007] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0008] A method for collaboratively measuring pressure and temperature of a piezoresistive MEMS pressure sensor comprises the following steps:

[0009] S1, switching the resistance connection mode of the MEMS head of the piezoresistive MEMS pressure sensor through the MOS switch to obtain the pressure and temperature signals in a time-sharing manner;

[0010] S2, using equivalent resistance Req to eliminate the influence of pressure on temperature measurement;

[0011] S3. Based on the pre-stored temperature-pressure characteristic curve, the temperature drift error is compensated in real time through a digital algorithm.

[0012] Furthermore, the piezoresistive MEMS pressure sensor includes a piezoresistive MEMS head, a MOS switch, a temperature measurement bridge, an instrument amplifier, a non-volatile memory, an analog-to-digital converter, a clock oscillator, a timing control circuit, an interface circuit, and a control logic and compensation algorithm circuit; the piezoresistive MEMS head is used to sense pressure and temperature; the temperature measurement bridge is a Wheatstone bridge for measuring temperature composed of a conditioning circuit and a piezoresistive MEMS head, and is used to measure temperature values; the MOS switch is used to switch the circuit connection relationship to achieve time-sharing sampling of temperature and pressure; the instrument amplifier is used to condition the voltage difference of the Wheatstone bridge so that its changes in the entire measurement range are connected The analog-to-digital converter samples and quantizes the amplified voltage to generate digital code values corresponding to different temperatures and pressures. The clock oscillator is used to generate the clock signal required for chip operation. The non-volatile memory is used to store the chip's adjustment coefficients and the configuration values of each module. The interface circuit is used to realize communication between the chip and an external controller, realize the configuration of internal circuit modules and update NVM data. The control logic and compensation algorithm circuit uses the temperature and pressure information collected by the analog-to-digital converter and the compensation algorithm in the NVM to perform real-time compensation for temperature and pressure, realize coordinated measurement and compensation of pressure and temperature curves, and compensate for errors caused by offset and process deviation.

[0013] Furthermore, in the pressure measurement mode, the piezoresistive MEMS head is a Wheatstone bridge composed of four piezoresistors R1, R2, R3, and R4, the common node of the resistors R1 and R4 is connected to the power supply VDD, the common node of R2 and R3 is grounded, the V1 node and the V2 node serve as output ends, and the output voltage is V12.

[0014] Furthermore, during the working process of measuring pressure: the piezoresistors are located in the arms of the Wheatstone bridge, and all four arms are composed of piezoresistors. When pressure acts on the piezoresistors, the resistances R1 and R3 of the two opposing piezoresistors increase, while the resistances R2 and R4 of the other two opposing piezoresistors decrease. According to Kirchhoff's law and Ohm's law, when the bridge is balanced, the output voltage V12 = 0, that is, R2:R1 = R4:R3; when pressure causes the strain gauge resistance to change, the bridge loses balance, and the output voltage V12 is no longer zero; the relationship between the output voltage V12 and the power supply voltage VDD and each resistor is: V12 = VDD × (R1 ÷ (R1 + R2) - R3 ÷ (R3 + R4)); under the action of pressure, changes in R1, R2, R3, and R4 will cause the result of this equation to change, that is, the output voltage V12 will change with the resistance change caused by pressure. When the output voltage of the bridge is measured, the corresponding pressure value can be obtained based on the calibration relationship.

[0015] Furthermore, in the temperature measurement mode, the four piezoresistors R1 , R2 , R3 , and R4 in the piezoresistive MEMS meter head form an equivalent resistance Req.

[0016] Furthermore, the resistance of the equivalent resistor Req is determined by the series-parallel combination of piezoresistors, so that the symmetrical resistance changes of Req cancel each other out when the pressure changes.

[0017] Furthermore, the equivalent resistor Req and R5, R6, and R7 in the conditioning chip of the instrumentation amplifier form a quadrilateral Wheatstone bridge, the common node of the resistor Req and R7 is connected to the power supply VDD, the common node of R5 and R6 is grounded, the V3 node and the V5 node serve as output ends, and the output voltage is V35.

[0018] Furthermore, during the temperature measurement process, resistor Req is located in an arm of the Wheatstone bridge as a thermistor, and the other three arms are fixed resistors R5, R6, and R7. When the temperature changes, the resistance value of Req will change accordingly, and the bridge balance will be broken. According to Kirchhoff's law and Ohm's law, when the bridge is balanced, the output voltage V35 = 0, that is, R5:Req = R7:R6. When pressure causes the strain gauge resistance to change, the bridge loses balance and the output voltage V35 is no longer zero. The relationship between the output voltage V12, the power supply voltage VDD, and each resistor is: V35 = VDD × (Req ÷ (Req + R5) – R6 ÷ (R6 + R7)). Under the influence of temperature, changes in Req will cause the result of this equation to change, that is, the output voltage V35 will change with the resistance change caused by temperature. When the output voltage of the bridge is measured, the corresponding temperature value can be obtained based on the calibration relationship.

[0019] Furthermore, the digital compensation algorithm compensates the pressure measurement results in real time through the temperature information collected by the ADC and the compensation algorithm in the NVM, thereby realizing errors caused by temperature curvature, offset and process deviation.

[0020] Beneficial effects: The present invention utilizes the piezoresistor of the piezoresistive MEMS sensor head to realize the coordinated measurement of pressure and temperature, and realizes the calibration and compensation of temperature and pressure through digital algorithms; reduces the design difficulty and process requirements of the piezoresistive temperature and pressure integrated sensor chip for the piezoresistive MEMS sensor head and signal conditioning circuit, improves the measurement accuracy of temperature and pressure, and reduces the development and manufacturing costs of the piezoresistive temperature and pressure integrated sensor chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 This is a flowchart of the steps of the pressure-temperature coordinated measurement method of the piezoresistive MEMS pressure sensor according to an embodiment of the present invention;

[0023] Figure 2 A schematic structural diagram of a piezoresistive MEMS pressure sensor in a pressure-temperature coordinated measurement method for a piezoresistive MEMS pressure sensor according to an embodiment of the present invention;

[0024] Figure 3 An equivalent circuit of the pressure measurement mode in the pressure-temperature coordinated measurement method of the piezoresistive MEMS pressure sensor according to an embodiment of the present invention;

[0025] Figure 4 The equivalent circuit of the temperature measurement mode in the pressure-temperature coordinated measurement method of the piezoresistive MEMS pressure sensor according to an embodiment of the present invention;

[0026] Figure 5 The Req mode equivalent circuit of the pressure-temperature coordinated measurement method of the piezoresistive MEMS pressure sensor according to an embodiment of the present invention;

[0027] Figure 6 This is a structural diagram of a typical instrumentation amplifier in the pressure-temperature coordinated measurement method of a piezoresistive MEMS pressure sensor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other.

[0029] Piezoresistive MEMS pressure sensors are pressure sensors manufactured using microelectronics and micromachining technologies. They work based on the piezoresistive effect. The specific principles are as follows:

[0030] The sensitive element senses pressure: The sensitive element of a piezoresistive MEMS pressure sensor is typically made of semiconductor materials such as single-crystal silicon. It often consists of a planar elastic silicon diaphragm with a sealed perimeter and fixed supports. The silicon material on the back of the diaphragm is removed, forming an inverted quadrilateral pyramidal cavity. When pressure acts on the sensitive element, the diaphragm elastically deforms.

[0031] The piezoresistive effect causes resistance changes: Semiconductor materials exhibit a piezoresistive effect. When subjected to stress, their internal lattice structure deforms, causing changes in the mobility and concentration of charge carriers (electrons or holes), and thus in the material's resistivity. As pressure increases, resistance also increases, and this change is proportional to the pressure.

[0032] Wheatstone bridge detection of resistance changes: Four high-precision semiconductor strain gauges (piezoresistive resistors) are typically arranged in a Wheatstone bridge configuration and placed near the edge or center of a planar diaphragm. When there's no pressure, the bridge is in equilibrium, and the output is zero. When pressure causes the resistance of the sensitive element to change, the Wheatstone bridge becomes unbalanced, outputting a pressure-dependent voltage signal. For example, when the measured pressure is applied, the resistance of one pair of arms increases while the resistance of the other pair decreases, causing the bridge to output an unbalanced voltage that varies linearly with the measured pressure.

[0033] Signal Conditioning and Output: The voltage signal output by the bridge is typically very weak and requires amplification by a signal conditioning circuit for subsequent signal processing, display, and transmission. Furthermore, because temperature changes can also affect the resistance of semiconductor materials, sensors often incorporate a temperature sensor. Temperature compensation algorithms implemented in software or hardware correct for temperature-related resistance changes, improving measurement accuracy.

[0034] In order to simultaneously measure pressure and temperature and reduce the impact of cross-sensitivity, thermal isolation, and temperature drift, traditional piezoresistive temperature and pressure integrated sensor chips use complex MEMS mechanical structures, which increases the design and manufacturing costs of MEMS. At the same time, they also require complex signal conditioning circuits, which increases the design difficulty and chip power consumption.

[0035] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0036] Example 1

[0037] Based on the design defects of the above existing technologies, see Figure 1-6 A pressure-temperature coordinated measurement method of a piezoresistive MEMS pressure sensor according to this embodiment includes the following steps:

[0038] S1, switching the resistance connection mode of the MEMS head of the piezoresistive MEMS pressure sensor through the MOS switch to obtain the pressure and temperature signals in a time-sharing manner;

[0039] S2, using equivalent resistance Req to eliminate the influence of pressure on temperature measurement;

[0040] S3. Based on the pre-stored temperature-pressure characteristic curve, the temperature drift error is compensated in real time through a digital algorithm.

[0041] This embodiment utilizes the piezoresistive MEMS sensor head piezoresistors to achieve coordinated measurement of pressure and temperature, and implements temperature and pressure calibration and compensation through digital algorithms; reduces the design difficulty and process requirements of the piezoresistive temperature and pressure integrated sensor chip for the piezoresistive MEMS sensor head and signal conditioning circuit, improves the measurement accuracy of temperature and pressure, and reduces the development and manufacturing costs of the piezoresistive temperature and pressure integrated sensor chip.

[0042] This embodiment realizes the coordinated measurement of temperature and pressure through time-sharing switching, equivalent resistance model and digital compensation algorithm; corresponding advantages: time-sharing multiplexing architecture: through switching by a single MEMS head and MOS switch, the hardware redundancy of the traditional dual-bridge parallel design is avoided, and the chip area and power consumption are reduced; cross-sensitivity suppression: the symmetry of the equivalent resistance Req is used to offset the interference of pressure on temperature measurement, avoiding the signal coupling problem when the traditional thermistor and piezoresistor are designed independently; dynamic compensation capability: based on the digital algorithm of the pre-stored temperature-pressure curve, the temperature drift error is corrected in real time, and the accuracy is greatly improved compared with hardware compensation.

[0043] In a specific embodiment, the piezoresistive MEMS pressure sensor includes a piezoresistive MEMS head, a MOS switch, a temperature measurement bridge, an instrument amplifier, a non-volatile memory, an analog-to-digital converter, a clock oscillator, a timing control circuit, an interface circuit, and a control logic and compensation algorithm circuit; the piezoresistive MEMS head is used to sense pressure and temperature; the temperature measurement bridge is a Wheatstone bridge for measuring temperature composed of a conditioning circuit and a piezoresistive MEMS head, and is used to measure temperature values; the MOS switch is used to switch the circuit connection relationship to achieve time-sharing sampling of temperature and pressure; the instrument amplifier is used to condition the voltage difference of the Wheatstone bridge so that it varies within the entire measurement range. The analog-to-digital converter samples and quantizes the amplified voltage to generate digital code values corresponding to different temperatures and pressures. The clock oscillator is used to generate the clock signal required for chip operation. The non-volatile memory is used to store the chip's adjustment coefficients and the configuration values of each module. The interface circuit is used to realize communication between the chip and an external controller, realize the configuration of internal circuit modules and update NVM data. The control logic and compensation algorithm circuit uses the temperature and pressure information collected by the analog-to-digital converter and the compensation algorithm in the NVM to perform real-time compensation for temperature and pressure, realize coordinated measurement and compensation of pressure and temperature curves, and compensate for errors caused by offset and process deviation.

[0044] This embodiment integrates a piezoresistive meter, MOS switches, signal conditioning circuits, a storage module, and a compensation algorithm. Advantages: Fully integrated solution: A single chip integrates signal acquisition, processing, and compensation functions, eliminating the need for external temperature-sensitive components or complex conditioning circuits, making it suitable for miniaturized scenarios (such as wearable devices). Modular design: Non-volatile memory (NVM) independently stores calibration parameters, supporting chip reuse and dynamic parameter updates, improving production line yield and flexibility. Low-power optimization: Through time-sharing sampling and dynamic clock management, power consumption is reduced compared to traditional parallel acquisition solutions.

[0045] To achieve coordinated measurement of temperature and pressure, see Figure 2 : In this embodiment, the time-sharing measurement of pressure and temperature is achieved through the combination of S0, S1, S2, S3, S4, S5, R5, R6, R7 and the timing control circuit in the conditioning circuit.

[0046] In pressure measurement mode, if Figure 2 As shown in Figure 1, switches S0, S4, and S5 are closed, switches S1, S2, S3, and S4 are open, the voltage at node V7 is equal to the voltage at node V1, and the voltage at node V6 is equal to the voltage at node V2. Node V3 is connected to ground through switch S0. The equivalent circuit is shown in Figure 1. Figure 3 shown.

[0047] In a specific example, in the pressure measurement mode, the piezoresistive MEMS head is a Wheatstone bridge composed of four piezoresistors R1, R2, R3, and R4, a quadrilateral structure, the common node of the resistors R1 and R4 is connected to the power supply VDD, the common node of R2 and R3 is grounded, the V1 node and the V2 node serve as output ends, and the output voltage is V12.

[0048] In the pressure mode of this embodiment, the varistors (R1-R4) form a quadrilateral Wheatstone bridge; corresponding advantages: high sensitivity: the response sensitivity of the four-varistor full-bridge structure to pressure deformation is more than twice that of the half-bridge design; symmetry suppresses common-mode interference: R1-R4 are symmetrically distributed in the center of the silicon membrane, offsetting the common-mode noise caused by the temperature gradient and improving the signal-to-noise ratio.

[0049] In a specific example, during pressure measurement, the following operating process occurs: piezoresistors are located in the arms of a Wheatstone bridge, with all four arms comprised of piezoresistors. When pressure is applied to the piezoresistors, the resistances of two opposing piezoresistors, R1 and R3, increase, while the resistances of two opposing piezoresistors, R2 and R4, decrease. According to Kirchhoff's law and Ohm's law, when the bridge is balanced, the output voltage V12 = 0, i.e., R2:R1 = R4:R3. When pressure causes the strain gauge resistance to change, the bridge loses balance, and the output voltage V12 is no longer zero. The relationship between the output voltage V12, the power supply voltage VDD, and the resistors is: V12 = VDD × (R1 ÷ (R1 + R2) - R3 ÷ (R3 + R4)). Under pressure, changes in R1, R2, R3, and R4 cause the result of this equation to change, i.e., the output voltage V12 varies with the resistance change caused by pressure. When the bridge output voltage is measured, the corresponding pressure value can be obtained based on the calibration relationship.

[0050] This embodiment's pressure measurement is based on the linear relationship between the bridge output voltage and resistance change. Advantages: Linear response: The bridge output voltage exhibits a linear relationship with pressure deformation (non-linearity <0.1% FS), simplifying the calibration process. Direct calibration capability: The direct mapping between V12 and pressure values reduces algorithm fitting complexity and computing resource requirements.

[0051] In temperature measurement mode, if Figure 2 As shown, switches S0, S4, and S5 are open, switches S1, S2, S3, and S4 are closed, the voltage at node V7 is equal to the voltage at nodes V3 and V4, and the voltage at node V6 is equal to the voltage at node V5. The equivalent circuit is shown in Figure 4 shown.

[0052] In a specific example, see Figure 5 : In the temperature measurement mode, the four piezoresistors R1, R2, R3, and R4 in the piezoresistive MEMS meter head form an equivalent resistance Req.

[0053] In the temperature mode of this embodiment, the piezoresistors are reorganized into equivalent resistors Req. The corresponding advantages are: hardware reuse: the MEMS meter head piezoresistors are reused as temperature sensors, eliminating the need for additional temperature-sensitive components (such as thermistors), reducing costs and packaging complexity; temperature isolation: the symmetrical structural design of Req eliminates the interference of pressure on temperature measurement.

[0054] In a specific example, the resistance of the equivalent resistor Req is determined by a series-parallel combination of piezoresistors, so that the symmetrical resistance changes of Req cancel each other out when the pressure changes.

[0055] The equivalent resistor Req of this embodiment is designed to symmetrically offset pressure variations. The corresponding advantages include: cross-sensitivity suppression: Pressure-induced resistance changes in R1-R4 are offset in Req (for example, R1↑ and R3↑, R2↓ and R4↓), ensuring that Req only responds to temperature changes; high stability: The resistance of Req is insensitive to process variations (tolerance <±1%), improving the repeatability of temperature measurements.

[0056] In a specific implementation, when pressure is applied to the piezoresistive MEMS meter head, the resistance of the two opposing piezoresistors increases (such as R1 and R3), while the resistance of the other two opposing piezoresistors decreases (such as R2 and R4). According to Formula 1, through reasonable design, the changes in R1 and R3 and R2 and R4 can offset each other, and the resistance value Req will not change with pressure. The temperature coefficient of resistance TC can be used to measure the piezoresistive MEMS meter head.

[0057] In a specific example, see Figure 4 : The equivalent resistor Req and R5, R6, and R7 in the conditioning chip of the instrumentation amplifier form a quadrilateral Wheatstone bridge. The common node of the resistor Req and R7 is connected to the power supply VDD, the common node of R5 and R6 is grounded, and the V3 node and the V5 node serve as output terminals, and the output voltage is V35.

[0058] The temperature measurement bridge of this embodiment consists of Req and fixed resistors (R5-R7). The corresponding advantages include: optimized temperature sensitivity: the fixed resistors R5-R7 use low temperature coefficient materials (such as thin film resistors), so that the bridge output only reflects the temperature variation characteristics of Req (sensitivity > 0.5mV / °C); anti-interference ability: the fixed resistors are placed in a low-stress area to avoid the influence of mechanical deformation on temperature measurement.

[0059] In a specific example, during temperature measurement, resistor Req serves as a thermistor in one arm of a Wheatstone bridge, while the other three arms contain fixed resistors R5, R6, and R7. When the temperature changes, the resistance of Req changes accordingly, disrupting the bridge's balance. According to Kirchhoff's law and Ohm's law, when the bridge is balanced, the output voltage V35 = 0, i.e., R5:Req = R7:R6. When pressure causes the strain gauge resistance to change, the bridge loses balance, and the output voltage V35 is no longer zero. The relationship between the output voltage V12, the power supply voltage VDD, and the resistors is: V35 = VDD × (Req ÷ (Req + R5) – R6 ÷ (R6 + R7)). Changes in Req under temperature cause the result of this equation to change, meaning that the output voltage V35 varies with the temperature-induced resistance change. By measuring the bridge's output voltage, the corresponding temperature value can be obtained based on the calibration relationship.

[0060] The temperature measurement of this embodiment is based on the linear relationship between the bridge output voltage and the temperature change of Req; the corresponding advantages are:

[0061] Temperature linearization: The temperature variation characteristics of Req are mapped with high precision through multi-point calibration and piecewise linear interpolation;

[0062] High signal-to-noise ratio: A low-pass filter is embedded in the temperature mode to suppress high-frequency noise.

[0063] In a specific example, the digital compensation algorithm compensates the pressure measurement results in real time through the temperature information collected by the ADC and the compensation algorithm in the NVM to achieve errors caused by temperature curvature, offset and process deviation.

[0064] The digital algorithm of this embodiment compensates for temperature curvature, offset and process deviation in real time; corresponding advantages:

[0065] Multi-dimensional compensation: Synchronously corrects zero temperature drift (α), sensitivity temperature drift (β), and nonlinear error (γ) through table lookup or polynomial fitting, achieving an accuracy of ±0.1% FS over the entire temperature range.

[0066] Real-time: The compensation algorithm is executed synchronously with ADC sampling to meet the needs of dynamic pressure measurement.

[0067] It should be noted that the instrumentation amplifier circuit of this embodiment is mainly composed of a two-stage differential amplifier circuit. Among them, the operational amplifiers A1 and A2 are in-phase differential input mode. The in-phase input can greatly increase the input impedance of the circuit and reduce the attenuation of the circuit to weak input signals; the differential input can make the circuit only amplify the differential mode signal, and only follow the common mode input signal, so that the amplitude ratio of the differential mode signal to the common mode signal sent to the subsequent stage (that is, the common mode rejection ratio CMRR) is improved. In this way, in the differential amplifier circuit composed of the operational amplifier A3 as the core component, under the condition that the CMRR requirements remain unchanged, the precision matching requirements for resistors R3 and R4, Rf and R5 can be significantly reduced, so that the instrumentation amplifier circuit has better common mode rejection capability than the simple differential amplifier circuit. Under the conditions of R1=R2, R3=R4, Rf=R5, the gain of the circuit in the example is: G=(1+2R1 / Rg)Rf / R3. It can be seen from the formula that the adjustment of the circuit gain can be achieved by changing the resistance value of Rg. As shown in the formula, the gain of the circuit can be adjusted by changing the resistance value of Rg. Figure 6 shown.

[0068] The ADC circuit can use SAR ADC, ΣΔ ADC, dual-slope ADC, and other ADC structures suitable for low speed and low power consumption. The number of ADC quantization bits should be selected according to the system accuracy requirements.

[0069] Since this application does not require high OSC frequency, the oscillation circuit can adopt a ring oscillator or relaxation oscillator structure, and generate the clock signals required by each module through a frequency division circuit.

[0070] NVM (non-volatile memory) is used to store the chip's trim coefficients and the configuration values of each module. It can use EEPROM, MTP, OTP, fuse or FLASH, and can be selected according to the specific process.

[0071] The digital interface circuit uses universal data interfaces such as I2C, SPI, UART or 1-wire to realize communication between the chip and the external controller, and to configure the internal circuit modules and update the NVM data.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for coordinating pressure and temperature measurement of a piezoresistive MEMS pressure sensor, characterized in that: The following steps are involved: S1, switching the resistance connection mode of the MEMS head of the piezoresistive MEMS pressure sensor through the MOS switch to obtain the pressure and temperature signals in a time-sharing manner; S2, using equivalent resistance Req to eliminate the influence of pressure on temperature measurement; S3. Based on the pre-stored temperature-pressure characteristic curve, the temperature drift error is compensated in real time through a digital algorithm.

2. The pressure-temperature coordinated measurement method of a piezoresistive MEMS pressure sensor according to claim 1, characterized in that: The piezoresistive MEMS pressure sensor includes a piezoresistive MEMS meter head, a MOS switch, a temperature measurement bridge, an instrumentation amplifier, a non-volatile memory, an analog-to-digital converter, a clock oscillator, a timing control circuit, an interface circuit, and a control logic and compensation algorithm circuit. The piezoresistive MEMS meter head is used to sense pressure and temperature. The temperature measurement bridge is a Wheatstone bridge composed of a conditioning circuit and the piezoresistive MEMS meter head, used to measure temperature values. The MOS switch is used to switch the circuit connection relationship to achieve time-sharing sampling of temperature and pressure. The instrumentation amplifier is used to condition the voltage difference of the Wheatstone bridge so that its variation within the entire measurement range is close to the full scale of the ADC. The analog-to-digital converter samples and quantizes the amplified voltage to generate digital code values corresponding to different temperatures and pressures; The clock oscillator is used to generate the clock signal required for chip operation; the non-volatile memory is used to store the chip's adjustment coefficients and the configuration values of each module; the interface circuit is used to realize communication between the chip and the external controller, realize the configuration of internal circuit modules and update NVM data; the control logic and compensation algorithm circuit uses the temperature and pressure information collected by the analog-to-digital converter and the compensation algorithm in the NVM to perform real-time compensation for temperature and pressure, realize coordinated measurement and compensation of pressure and temperature curves, and compensate for errors caused by offset and process deviation.

3. The pressure-temperature coordinated measurement method of a piezoresistive MEMS pressure sensor according to claim 2, characterized in that: In the pressure measurement mode, the piezoresistive MEMS meter head is a Wheatstone bridge with a quadrilateral structure composed of four piezoresistors R1, R2, R3, and R4. The common node of the resistors R1 and R4 is connected to the power supply VDD, the common node of R2 and R3 is grounded, and the V1 node and the V2 node serve as output terminals, and the output voltage is V12.

4. The pressure-temperature coordinated measurement method of a piezoresistive MEMS pressure sensor according to claim 3, characterized in that: The working process when measuring pressure: Piezoresistors are located in the arms of a Wheatstone bridge, and all four arms are composed of piezoelectric resistors. When pressure acts on the piezoelectric resistors, the resistances of the two opposing piezoelectric resistors, R1 and R3, increase, while the resistances of the other two opposing piezoelectric resistors, R2 and R4, decrease. According to Kirchhoff's law and Ohm's law, when the bridge is balanced, the output voltage V12 = 0, that is, R2:R1 = R4:R3. When pressure causes the strain gauge resistance to change, the bridge loses balance, and the output voltage V12 is no longer zero. The relationship between the output voltage V12, the power supply voltage VDD, and the various resistors is: V12 = VDD × (R1 ÷ (R1 + R2) - R3 ÷ (R3 + R4)). Under the action of pressure, changes in R1, R2, R3, and R4 will cause the result of this equation to change, that is, the output voltage V12 will change with the resistance change caused by pressure. When the output voltage of the bridge is measured, the corresponding pressure value can be obtained based on the calibration relationship.

5. The pressure-temperature coordinated measurement method of a piezoresistive MEMS pressure sensor according to claim 2, characterized in that: In the temperature measurement mode, the four piezoresistors R1 , R2 , R3 , and R4 in the piezoresistive MEMS meter head form an equivalent resistance Req.

6. The pressure-temperature coordinated measurement method of a piezoresistive MEMS pressure sensor according to claim 5, characterized in that: The resistance of the equivalent resistor Req is determined by the series-parallel combination of the piezoresistors, so that the symmetrical resistance changes of Req cancel each other out when the pressure changes.

7. The pressure-temperature coordinated measurement method of a piezoresistive MEMS pressure sensor according to claim 6, characterized in that: The equivalent resistor Req and R5, R6, and R7 in the conditioning chip of the instrumentation amplifier form a quadrilateral Wheatstone bridge. The common node of the resistor Req and R7 is connected to the power supply VDD, the common node of R5 and R6 is grounded, and the V3 node and the V5 node serve as output terminals, and the output voltage is V35.

8. The pressure-temperature coordinated measurement method of a piezoresistive MEMS pressure sensor according to claim 7, characterized in that: During temperature measurement, resistor Req acts as a thermistor in one arm of a Wheatstone bridge circuit, while the other three arms contain fixed resistors R5, R6, and R7. When the temperature changes, the resistance of Req changes accordingly, disrupting the bridge's balance. According to Kirchhoff's and Ohm's laws, when the bridge is balanced, the output voltage V35 = 0, i.e., R5:Req = R7:R6. When pressure causes the strain gauge resistance to change, the bridge loses balance, and the output voltage V35 is no longer zero. The relationship between output voltage V12, power supply voltage VDD, and each resistor is: V35 = VDD × (Req ÷ (Req + R5) – R6 ÷ (R6 + R7)). Changes in Req under temperature change the result of this equation, meaning that output voltage V35 varies with the temperature-induced resistance change. By measuring the bridge's output voltage, the corresponding temperature value can be obtained based on the calibration relationship.

9. The pressure-temperature coordinated measurement method of a piezoresistive MEMS pressure sensor according to claim 1, characterized in that: The digital compensation algorithm uses the temperature information collected by the ADC and the compensation algorithm in the NVM to compensate the pressure measurement results in real time, realizing errors caused by temperature curvature, offset and process deviation.

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