High-precision silicon piezoresistive pressure sensing device and method

Abstract

The invention provides a high-precision silicon piezoresistive pressure sensing device and method. Comprising a pressure sensitive assembly, a circuit assembly and a supporting structure. The pressure-sensitive assembly comprises a pressure chip with an isolation packaging structure and a pressure-sensitive connecting nozzle, the pressure chip and the pressure-sensitive connecting nozzle are combined into a whole in a welding manner, and the pressure-sensitive connecting nozzle provides a transmission channel for the pressure of a measured medium; the pressure sensitive assembly is connected with the circuit assembly in a wire-free connection mode, a signal of a pressure chip is transmitted to the circuit assembly, and the circuit assembly is fixed on the supporting structure; the pressure sensitive assembly comprises a pressure chip with an isolation packaging structure and a pressure sensitive connecting nozzle, and the pressure chip and the pressure sensitive connecting nozzle are combined into a whole in a welding manner; a constant current source instead of a traditional constant voltage source is used for supplying power to the pressure chip in an excitation mode. On the premise that a traditional isolation packaging structure is not changed, high pressure measurement precision is achieved by constructing different circuit forms.

Description

Technical Field

[0001] This invention belongs to the field of airborne sensor technology, specifically relating to a high-precision silicon piezoresistive pressure sensing device and method. Background Technology

[0002] In the field of airborne aviation, pressure sensors are required to measure the pressure of liquid or gaseous media in systems such as hydraulics, fuel systems, and cockpit systems. Silicon piezoresistive pressure sensors are the most commonly used in these applications. The core of a silicon piezoresistive pressure sensor is a Wheatstone bridge, whose output signal is extremely weak (on the order of millivolts) and is severely affected by temperature drift (zero-point drift and sensitivity drift) and nonlinear errors.

[0003] Currently, the silicon piezoresistive pressure sensors used on airborne systems often employ, for example... Figure 1 The proposed solution involves protecting the pressure chip through an isolated packaging structure, followed by using a dedicated conditioning chip to condition the pressure chip's output into an analog voltage or current output. However, the introduction of the isolated packaging structure directly results in a loss of pressure measurement accuracy. Furthermore, the dedicated conditioning chip requires an independent temperature sensor to measure the ambient temperature, but the temperature of this sensor differs from that of the pressure chip, leading to inaccurate compensation. Consequently, the highest accuracy of existing pressure sensors across the entire temperature range can only reach 0.5%FS. Summary of the Invention

[0004] The purpose of this invention is to provide a high-precision silicon piezoresistive pressure sensing device and method, which improves the measurement accuracy of the sensing device without changing the isolation packaging structure.

[0005] According to a first aspect of the present invention, a high-precision silicon piezoresistive pressure sensing device is provided, comprising a pressure-sensitive component, a circuit component, and a support structure; the pressure-sensitive component includes a pressure chip with an isolated encapsulation structure and a pressure-sensing connector, which are integrated by welding, wherein the pressure-sensing connector provides a transmission channel for the pressure of the measured medium; the pressure-sensitive component and the circuit component are connected by a wireless connection, transmitting the signal from the pressure chip to the circuit component; the circuit component is fixed on the support structure and is used to condition and process the signal from the pressure chip, thereby improving the accuracy of the sensor.

[0006] The pressure-sensitive component comprises a pressure chip with an isolated encapsulation structure and a pressure-sensitive connector, which are bonded together as a single unit. Its miniaturized design allows it to be used in a wider range of installation applications, especially in space-constrained locations. A constant current source, rather than a traditional constant voltage source, is used to power the pressure chip to partially compensate for sensitivity temperature drift.

[0007] In one possible embodiment, the pressure chip includes a glass substrate, a silicon wafer, and four resistor strips symmetrically distributed on the silicon wafer. The resistor strips are manufactured using micromachining processes, and the four resistor strips are interconnected by wires on the silicon wafer to form a Wheatstone bridge, enabling the transformation of physical quantities. The glass substrate and the silicon wafer are bonded together by electrostatic bonding.

[0008] In one possible embodiment, the circuit assembly includes an excitation circuit module, a pressure signal amplification and acquisition circuit module, a temperature signal amplification and acquisition circuit module, and a data storage circuit module. The excitation circuit module processes the external power supply and provides excitation to other modules and the pressure-sensitive component within the circuit assembly. The pressure signal amplification and acquisition circuit module amplifies and processes the pressure characterization signal output by the pressure-sensitive component and transmits it via an SPI interface. The temperature signal amplification and acquisition circuit module amplifies and processes the temperature characterization signal output by the pressure-sensitive component and transmits it via an SPI interface. The data storage module stores various coefficients for calculating pressure and temperature signals and transmits these coefficients to an upstream system or device via the SPI interface for calculating temperature and pressure values.

[0009] In one possible embodiment, the excitation circuit module consists of a voltage conversion circuit and a constant current source generation circuit; the voltage conversion circuit converts the input supply voltage VCC into a 3.3V output for use by other modules in the circuit assembly; the constant current source generation circuit generates a constant current Iref under the excitation of the supply voltage VCC to power the pressure-sensitive component.

[0010] In one possible embodiment, the pressure signal amplification and acquisition circuit module uses a 24-bit analog-to-digital converter U1 with a programmable amplifier, wherein the AIN1+ and AIN1- pins are signal input pins of the on-chip amplifier. The AIN1+ pin is connected to the junction of R2 and R4 of the Wheatstone bridge of the pressure chip, and the AIN1- pin is connected to the junction of R1 and R3 of the Wheatstone bridge of the pressure chip to acquire the signal characterizing the pressure.

[0011] In one possible embodiment, the temperature signal amplification and acquisition circuit module uses a 16-bit analog-to-digital converter U2 with a programmable amplifier. The AIN1+ and AIN1- pins are the signal input pins of the analog-to-digital converter. The AIN- pin is connected to ground potential, and the AIN+ pin is connected to the junction of R1 and R2 of the Wheatstone bridge of the pressure chip for acquiring signals characterizing temperature.

[0012] In one possible embodiment, the SPI signal processed by the pressure signal amplification and acquisition circuit module and the temperature signal amplification and acquisition circuit module can also be converted into an analog voltage / current signal by a high-precision DAC.

[0013] According to a second aspect of the present invention, a high-precision silicon piezoresistive pressure sensing method is provided, employing the aforementioned high-precision silicon piezoresistive pressure sensing device, comprising the following steps: Step 1: Select m temperature points within the operating temperature range of the pressure sensing device, and perform n pressure tests on the device at each temperature point; obtain m voltage data representing the temperature, denoted as {T1, T2, ..., T...} m}; and m n voltage data representing pressure, denoted as

[0014] Step 2: Solve for the temperature calculation coefficients according to formula (1); (1) in, The m actual temperature values ​​from step 1, in °C; T represents the voltage data representing the m temperatures tested in step 1; g1...g4 are the calculated temperature coefficients. Step 3: Solve for the pressure calculation coefficients according to formula (2); (2) in, m actually applied in step 1 n pressure values, in kPa; P is the m tested in step 1. n voltage data representing pressure; T represents the voltage data representing the temperature obtained in step 1; b ji To obtain the pressure solution coefficients; Step 4: Calculate the temperature and pressure values ​​under the current environment using formulas (1) and (2); Substitute g1……g4 into formula (1) and b respectively. ji Substituting into formula (2), the actual temperature and pressure values ​​can be calculated based on the measured voltage signals representing temperature and pressure.

[0015] Advantages and beneficial effects of the present invention: This invention achieves high pressure measurement accuracy by constructing different circuit configurations without altering the traditional isolated packaging structure. By synchronously acquiring pressure and temperature signals, it eliminates compensation errors caused by temperature measurement lag. The pressure chip within the pressure-sensitive component simultaneously senses temperature and pressure, reducing the need for external temperature sensing compared to traditional solutions, thus improving the reliability of temperature compensation from the source and further reducing the overall product size. All compensation coefficients are written into the data storage module during automated factory calibration, ensuring product consistency and interchangeability. Pressure-sensitive components with different ranges and performance levels can all be adapted to the same compensation algorithm, demonstrating a high degree of platformization. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram showing the configuration of an existing pressure sensor; Figure 2 This is a schematic diagram showing the configuration of the pressure sensor of the present invention; Figure 3 This is a schematic diagram of the pressure chip structure; Figure 4 This is a schematic diagram of the excitation circuit module; Figure 5 This is a detailed circuit diagram of the pressure / temperature signal amplification and acquisition circuit module. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0020] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0022] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0024] This invention implements a comprehensive cockpit ergonomics evaluation tool based on an indicator system. It consists of six parts: a data synchronization module, a comprehensive processing module, a test task module, an analysis results module, a comprehensive evaluation module, and a data management module. Residing at the test workstation, it collects test data and clock source signals through a time synchronization controller, completing the test task planning and organization, process data processing and analysis, and subjective and objective comprehensive evaluation of cockpit ergonomics. The following describes the composition of each module in this evaluation tool and its usage process.

[0025] This invention provides a high-precision silicon piezoresistive pressure sensor. Without changing the traditional isolation packaging structure, the overall size is reduced by miniaturizing the pressure-sensing connector, making it applicable to more space-constrained situations. The measurement accuracy of the sensor can be improved by constructing different circuit configurations.

[0026] like Figure 2 As shown: The high-precision silicon piezoresistive pressure sensor includes a pressure-sensitive component, a circuit component, and a support structure. The pressure-sensitive component and the circuit component are connected wirelessly, transmitting the signal from the pressure chip to the circuit component. The support structure is integrated with the pressure-sensitive component using screws, providing an effective mounting and securing method for the circuit component. The circuit component contains various functional circuit modules that condition and process the signal from the pressure chip, thereby improving the sensor's measurement accuracy.

[0027] The pressure-sensitive component comprises a pressure chip with an isolated encapsulation structure and a pressure-sensing connector, which are welded together as a single unit. The pressure-sensing connector provides a transmission channel for the pressure of the measured medium, and its miniaturized design allows it to be used in a wider range of installation applications, especially in space-constrained locations. The pressure chip converts the sensed pressure into a change in the resistance of its own bridge circuit. Under electrical signal excitation, it outputs a millivolt-level voltage signal corresponding to the measured pressure. Innovatively, it utilizes the temperature sensitivity of the bridge resistance itself to achieve temperature sensing, serving as a temperature measurement source for pressure chip temperature compensation, which is more accurate than external temperature sensors. For excitation, a constant current source is used instead of a traditional constant current source to power the bridge circuit, compensating for some of the pressure chip's sensitivity temperature drift.

[0028] like Figure 3 , Figure 4 As shown, the circuit components include an excitation circuit module, a pressure signal amplification and acquisition circuit module, a temperature signal amplification and acquisition circuit module, and a data storage circuit module.

[0029] The excitation circuit module processes the external power supply and provides excitation to both the internal circuit module and the pressure-sensitive component. The internal circuit module uses voltage excitation, while the pressure-sensitive component uses current excitation.

[0030] The pressure signal amplification and acquisition circuit module amplifies and processes the pressure characterization signal output by the pressure-sensitive component, and then transmits it through the SPI interface; the temperature signal amplification and acquisition circuit module amplifies and processes the temperature characterization signal output by the pressure-sensitive component, and then transmits it through the SPI interface.

[0031] like Figure 5 As shown: The pressure / temperature signal amplification and acquisition circuit module includes high-precision ADC chips U1 and U2 with programmable amplifiers, capacitors C1-C4, and inductor L1. U1 adaptively amplifies the millivolt-level voltage signal representing the pressure signal output from the pressure chip and transmits the converted data via an SPI interface. U2 performs analog-to-digital conversion on the voltage signal representing the temperature signal output from the pressure chip and transmits the data via an SPI interface. C1 is connected to the power supply pin VDD of U2 to filter the power supply and ensure stable power supply to U2. C4 is connected to the digital power supply pin DVDD of U1 to filter the power supply and ensure stable power supply to U1. C2 and C3 are connected to the analog power supply pin AVDD of U1 to filter and stabilize the analog power supply of U1, and then connected to the digital power supply pin DVDD of U1 via a ferrite bead L1 to isolate the digital and analog power supplies and filter out fluctuations caused by the digital power supply.

[0032] The data storage module stores various coefficients for calculating pressure and temperature signals and transmits these coefficients to the upper-level system or equipment via the SPI interface. During factory calibration, five temperature points and six pressure points are selected within the full temperature range of (-55~125)℃. The outputs of U1 and U2 at each test point are recorded. All coefficients required for the pressure calculation model are calculated using a pre-set calculation template, and these coefficients are stored in the data storage module in a standardized format. In use, these coefficients are loaded via the SPI interface, and the measured pressure signal is obtained according to the calculation model.

[0033] Testing showed that the pressure sensor's accuracy is better than ±0.08%FS across the entire temperature range, significantly superior to similar traditional products.

[0034] Optionally, the SPI signal processed by the pressure signal amplification and acquisition circuit module and the temperature signal amplification and acquisition circuit module can also be converted into an analog voltage / current signal by a high-precision DAC.

[0035] A high-precision silicon piezoresistive pressure sensing method, employing the aforementioned high-precision silicon piezoresistive pressure sensing device, includes the following steps: Step 1: Select 5 temperature points within the operating temperature range of the pressure sensor, and perform 6 pressure tests at each temperature point. Obtain the voltage data for 5 temperature points, denoted as {T1, T2, ..., T5}; and the voltage data for 30 pressure points, denoted as...

[0036] Step 2: Solve for the temperature calculation coefficient according to formula (1).

[0037] (1) in, These are the five actual temperature values ​​from step 1, in °C. T represents the voltage data {T1, T2, ..., T6} for the five temperatures tested in step 1; g1……g4 are the temperature calculation coefficients obtained from the solution.

[0038] Step 3: Solve for the pressure calculation coefficients according to formula (2).

[0039] (2) in, These are the 30 pressure values ​​actually applied in step 1, in kPa. P represents the voltage data representing the pressure measured in step 1. ; T represents the voltage data {T1, T2, ..., T5} for the five temperatures tested in step 1; b ji The pressure calculation coefficient is obtained by solving for it.

[0040] Step 4: Combine formulas (1) and (2) to calculate the temperature and pressure values ​​under the current environment.

[0041] Substitute g1……g4 into formula (1) and b respectively. ji Substituting into formula (2), the actual temperature and pressure values ​​can be calculated based on the measured voltage signals representing temperature and pressure.

[0042] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A high-precision silicon piezoresistive pressure sensing device, characterized in that, The device includes a pressure-sensitive component, a circuit assembly, and a support structure. The pressure-sensitive component comprises a pressure chip with an isolated encapsulation structure and a pressure-sensing connector, which are welded together to form a single unit. The pressure-sensing connector provides a transmission channel for the pressure of the measured medium. The pressure-sensitive component is connected to the circuit assembly via a wireless connection, transmitting the signal from the pressure chip to the circuit assembly. The circuit assembly is fixed to the support structure. The device uses a constant current source instead of a traditional constant voltage source to power the pressure chip.

2. The high-precision silicon piezoresistive pressure sensing device according to claim 1, characterized in that, The pressure chip includes a glass substrate, a silicon wafer, and four resistor strips symmetrically distributed on the silicon wafer. The resistor strips are manufactured using micromachining technology, and the four resistor strips are interconnected by wires on the silicon wafer to form a Wheatstone bridge, thereby realizing the transformation of physical quantities.

3. The high-precision silicon piezoresistive pressure sensing device according to claim 1, characterized in that, The circuit assembly includes an excitation circuit module, a pressure signal amplification and acquisition circuit module, a temperature signal amplification and acquisition circuit module, and a data storage circuit module. The excitation circuit module processes the external power supply and provides excitation to other modules and the pressure-sensitive component within the circuit assembly. The pressure signal amplification and acquisition circuit module amplifies and processes the pressure characterization signal output from the pressure-sensitive component and transmits it via an SPI interface. The temperature signal amplification and acquisition circuit module amplifies and processes the temperature characterization signal output from the pressure-sensitive component and transmits it via an SPI interface. The data storage module stores various coefficients for calculating pressure and temperature signals and transmits these coefficients to an upstream system or device via the SPI interface for calculating temperature and pressure values.

4. The high-precision silicon piezoresistive pressure sensing device according to claim 1, characterized in that, The excitation circuit module consists of a voltage conversion circuit and a constant current source generation circuit. The voltage conversion circuit converts the input power supply voltage VCC into a 3.3V output for use by other modules in the circuit assembly. The constant current source generation circuit generates a constant current Iref under the excitation of the power supply VCC, which is used to power the pressure-sensitive component.

5. The high-precision silicon piezoresistive pressure sensing device according to claim 1, characterized in that, The pressure signal amplification and acquisition circuit module uses a 24-bit analog-to-digital converter U1 with a programmable amplifier. The AIN1+ and AIN1- pins are the signal input pins of the on-chip amplifier. The AIN1+ pin is connected to the junction of R2 and R4 of the Wheatstone bridge of the pressure chip, and the AIN1- pin is connected to the junction of R1 and R3 of the Wheatstone bridge of the pressure chip to acquire the signal representing the pressure.

6. The high-precision silicon piezoresistive pressure sensing device according to claim 1, characterized in that, The temperature signal amplification and acquisition circuit module uses a 16-bit analog-to-digital converter U2 with a programmable amplifier. The AIN1+ and AIN1- pins are the signal input pins of the analog-to-digital converter. The AIN- pin is connected to ground potential, and the AIN+ pin is connected to the junction of R1 and R2 of the Wheatstone bridge of the pressure chip to acquire the signal characterizing the temperature.

7. The high-precision silicon piezoresistive pressure sensing device according to claim 1, characterized in that, The SPI signal, after being processed by the pressure signal amplification and acquisition circuit module and the temperature signal amplification and acquisition circuit module, can also be converted into an analog voltage / current signal by a high-precision DAC.

8. A high-precision silicon piezoresistive pressure sensing method, characterized in that, The high-precision silicon piezoresistive pressure sensing device according to any one of claims 1-7 includes the following steps: Step 1: Select m temperature points within the operating temperature range of the pressure sensing device, and perform n pressure tests on the device at each temperature point; obtain m voltage data representing the temperature, denoted as {T1, T2, ..., T...} m }; and m n voltage data representing pressure, denoted as Step 2: Solve for the temperature calculation coefficients according to formula (1); （1） in, The m actual temperature values ​​from step 1, in °C; T represents the voltage data representing the m temperatures tested in step 1; g1...g4 are the calculated temperature coefficients. Step 3: Solve for the pressure calculation coefficients according to formula (2); （2） in, m actually applied in step 1 n pressure values, in kPa; P is the m tested in step 1. n voltage data representing pressure; T represents the voltage data representing the temperature obtained in step 1; b ji To obtain the pressure solution coefficients; Step 4: Calculate the temperature and pressure values ​​under the current environment using formulas (1) and (2); Substitute g1……g4 into formula (1) and b respectively. ji Substituting into formula (2), the actual temperature and pressure values ​​can be calculated based on the measured voltage signals representing temperature and pressure.

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