Temperature compensation hybrid integrated circuit for silicon piezoresistive pressure sensors

Abstract

The application discloses a temperature compensation hybrid integrated circuit of a silicon piezoresistive pressure sensor. When the pressure sensor senses pressure, a pressure sensing bridge outputs corresponding voltage signals. The input end of a control unit is connected with the pressure sensing unit, which is used for collecting voltage signals after voltage division of a voltage division resistor, so that corresponding temperature of the pressure sensor is obtained according to the voltage signals after voltage division, and corresponding zero point compensation signals and sensitivity compensation signals are output according to the temperature. The input end of a zero point compensation unit is connected with the first output end of the control unit, and the zero point compensation unit compensates according to the zero point compensation signals. The input end of a sensitivity compensation unit is connected with the second output end of the control unit, and the sensitivity compensation unit compensates according to the sensitivity compensation signals. The output ends of the pressure sensing unit and the zero point compensation unit are connected with an amplification unit respectively, the amplification unit amplifies and compensates the voltage signals, and outputs standard signals, so that the output precision is improved.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a temperature-compensated hybrid integrated circuit for a silicon piezoresistive pressure sensor. Background Technology

[0002] In related technologies, existing pressure sensor temperature compensation methods mainly include analog compensation and signal conditioning chip compensation. Analog compensation typically has an output voltage ≤100mV, a typical room temperature accuracy of 0.5%FS, and a typical full-temperature accuracy of 1.5%FS. Its accuracy is relatively poor, and the output varies proportionally with the supply voltage, affecting the output accuracy. Signal conditioning chip compensation generally uses the ZSC31015 chip from ZMD (Germany) or the MAX1452 chip from Maxim Integrated. The ZSC31015 chip has fewer temperature and pressure compensation points, and it uses an AD converter to acquire the sensor signal first, then a DA converter for output. The conversion speed affects the sensor's response time, and the number of bits in the DA converter affects the output accuracy. The MAX1452 chip can only use its internal temperature sensor. When there is a temperature gradient between the pressure sensor (silicon piezoresistive chip) and the MAX1452 chip, or when the product requires rapid temperature change (temperature change rate ≥10℃ / min) testing, the output accuracy is poor, exceeding 1%FS. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in the aforementioned technologies. Therefore, the objective of this invention is to propose a temperature-compensated hybrid integrated circuit for a silicon piezoresistive pressure sensor. By utilizing the resistance temperature drift characteristics of the pressure sensor and using the silicon piezoresistive chip as a temperature reference, there is no temperature field gradient problem between the pressure sensor and the temperature compensation chip. Even when the product is in a rapidly changing temperature environment, high-precision output can still be guaranteed.

[0004] To achieve the above objectives, this invention proposes a temperature compensation hybrid integrated circuit for a silicon piezoresistive pressure sensor, comprising: a pressure sensing unit, which includes a pressure-sensing bridge and a voltage-dividing resistor, the pressure-sensing bridge being connected to the voltage-dividing resistor, and the pressure sensing unit outputting a corresponding voltage signal when the pressure sensor senses pressure; and a control unit, the input terminal of which is connected to the pressure sensing unit, the control unit being used to acquire the voltage signal after voltage division by the voltage-dividing resistor, so as to obtain the temperature corresponding to the pressure sensor based on the voltage signal after voltage division, and output corresponding zero-point compensation signal and sensitivity compensation signal based on the temperature; A zero-point compensation unit, the input of which is connected to the first output of the control unit, performs temperature compensation based on the zero-point compensation signal; a sensitivity compensation unit, the input of which is connected to the second output of the control unit, and the output of which is connected to the pressure sensing unit, performs temperature compensation based on the sensitivity compensation signal; and an amplification unit, connected to the outputs of both the pressure sensing unit and the zero-point compensation unit, amplifies and temperature-compensates the voltage signal, and outputs a standard signal.

[0005] The temperature compensation hybrid integrated circuit for the silicon piezoresistive pressure sensor proposed in this invention outputs a corresponding voltage signal when the pressure sensor senses pressure via a pressure-sensing bridge. The input terminal of the control unit is connected to the pressure-sensing unit to collect the voltage signal after voltage division by the voltage divider resistor, so as to obtain the temperature corresponding to the pressure sensor based on the voltage signal after voltage division, and output corresponding zero-point compensation signal and sensitivity compensation signal based on the temperature. The input terminal of the zero-point compensation unit is connected to the first output terminal of the control unit, and the zero-point compensation unit performs temperature compensation based on the zero-point compensation signal. The input terminal of the sensitivity compensation unit is connected to the second output terminal of the control unit, and the output terminal of the sensitivity compensation unit is connected to the pressure-sensing unit, and the sensitivity compensation unit performs temperature compensation based on the sensitivity compensation signal. The amplification unit is connected to the output terminals of the pressure-sensing unit and the zero-point compensation unit respectively, and the amplification unit amplifies the voltage signal and performs temperature compensation, and outputs a standard signal. Thus, by utilizing the resistance temperature drift characteristics of the pressure sensor and using the silicon piezoresistive chip as the temperature reference, there is no temperature field gradient problem between the pressure sensor and the temperature compensation chip, and high-precision output can be guaranteed even when the product is in a rapidly changing temperature environment.

[0006] In addition, the temperature compensation hybrid integrated circuit for the silicon piezoresistive pressure sensor proposed above according to the present invention may also have the following additional technical features:

[0007] Optionally, the voltage-sensing bridge includes a first resistor, a second resistor, a third resistor, and a fourth resistor, wherein the first resistor, the second resistor, the third resistor, and the fourth resistor are connected in series, and the voltage divider resistor is connected between the second resistor and the third resistor.

[0008] Optionally, the first input terminal of the control unit is connected between the voltage divider resistor and the voltage-sensing bridge.

[0009] Optionally, the second input terminal of the control unit is used to communicate with the outside in order to write temperature compensation data.

[0010] Optionally, the amplification unit includes an instrumentation amplifier, the positive input terminal of which is connected between the third resistor and the fourth resistor, and the negative input terminal of which is connected between the first resistor and the second resistor.

[0011] Optionally, the zero-point compensation unit includes a fifth resistor, a first capacitor, and a first operational amplifier. The output terminal of the first operational amplifier is connected to the amplification unit, the first input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier, the second input terminal of the first operational amplifier is connected to the first output terminal of the control unit through the fifth resistor, and the second input terminal of the first operational amplifier is also connected to ground through the first capacitor.

[0012] Optionally, the sensitivity compensation unit includes a sixth resistor, a second capacitor, and a second operational amplifier. The output terminal of the second operational amplifier is connected between the first resistor and the fourth resistor. The first input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier. The second input terminal of the second operational amplifier is connected to the second output terminal of the control unit through the sixth resistor. The second input terminal of the second operational amplifier is also connected to ground through the second capacitor.

[0013] Optionally, the amplification unit is also connected to an adjustment resistor so that the amplification factor can be adjusted via the adjustment resistor. Attached Figure Description

[0014] Figure 1 This is a circuit diagram of a temperature compensation hybrid integrated circuit for a silicon piezoresistive pressure sensor according to an embodiment of the present invention. Detailed Implementation

[0015] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0016] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0017] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0018] refer to Figure 1 As shown, the temperature compensation hybrid integrated circuit of the silicon piezoresistive pressure sensor proposed in this embodiment of the invention includes a pressure sensing unit 10 and a temperature compensation hybrid integrated unit 20. The temperature compensation hybrid integrated unit 20 includes a control unit, a zero-point compensation unit, a sensitivity compensation unit, and an amplification unit.

[0019] The pressure sensing unit 10 includes a pressure-sensing bridge and a voltage-dividing resistor R7. The pressure-sensing bridge is connected to the voltage-dividing resistor R7. The pressure sensing unit 10 is used to output a corresponding voltage signal when the pressure sensor senses pressure.

[0020] It should be noted that the voltage divider resistor R7 is a standard resistor, i.e., a fixed resistor.

[0021] As one embodiment, the voltage-sensing bridge includes a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4, which are connected in series. A voltage divider resistor R7 is connected between the second resistor R2 and the third resistor R3.

[0022] In other words, the bridge arm resistors of the voltage-sensing bridge include a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 are connected end to end, and the voltage divider resistor R7 is connected to the common terminal of the second resistor R2 and the third resistor R3.

[0023] It should be noted that the pressure-sensing bridge is the Wheatstone bridge of a silicon piezoresistive pressure sensor. When the piezoelectric sensor senses pressure, the resistance of the bridge arms of the pressure-sensing bridge changes and outputs a millivolt voltage signal. The resistance of the bridge arms of the silicon piezoresistive pressure sensor's pressure-sensing bridge changes with temperature. That is, when the temperature increases, the resistance of the bridge arms increases. A small temperature-drift fixed resistor, namely the voltage divider resistor R7, is connected in series at the lower end of the pressure-sensing bridge. According to the voltage divider principle, the voltage across the voltage divider resistor R7 changes with the temperature.

[0024] The input terminal of the control unit is connected to the pressure sensing unit. The control unit is used to acquire the voltage signal after voltage division by the voltage divider resistor R7, so as to obtain the temperature corresponding to the pressure sensor based on the voltage signal after voltage division, and output the corresponding zero-point compensation signal and sensitivity compensation signal based on the temperature.

[0025] As an example, the first input terminal ADC of the control unit is connected between the voltage divider resistor R7 and the voltage-sensing bridge.

[0026] In other words, the first input terminal ADC of the control unit is connected between the voltage divider resistor R7 and the pressure bridge to collect the voltage signal after voltage division by the voltage divider resistor R7. Based on the voltage signal, the temperature data corresponding to the silicon piezoresistive pressure sensor is obtained. Based on the temperature data, the duty cycle signals of PWM1 and PWM2 are output to compensate for the zero-point temperature drift and sensitivity temperature drift of the silicon piezoresistive pressure sensor, thereby achieving the purpose of high-precision output.

[0027] As one example, the second input terminal OWI of the control unit is used to communicate with the outside in order to write temperature compensation data.

[0028] In other words, the control unit obtains external temperature compensation data through the second input terminal OWI, so as to output the duty cycle signals of PWM1 and PWM2 according to the temperature data and the corresponding temperature compensation data to compensate for the zero-point temperature drift and sensitivity temperature drift of the silicon piezoresistive pressure sensor.

[0029] The input terminal of the zero-point compensation unit is connected to the first output terminal of the control unit, and the zero-point compensation unit performs temperature compensation based on the zero-point compensation signal.

[0030] As an example, the zero-point compensation unit includes a fifth resistor R5, a first capacitor C1, and a first operational amplifier A1. The output terminal of the first operational amplifier A1 is connected to the amplification unit, the first input terminal of the first operational amplifier A1 is connected to the output terminal of the first operational amplifier A1, the second input terminal of the first operational amplifier A1 is connected to the first output terminal of the control unit through the fifth resistor R5, and the second input terminal of the first operational amplifier A1 is also connected to ground through the first capacitor C1.

[0031] The input terminal of the sensitivity compensation unit is connected to the second output terminal of the control unit, and the output terminal of the sensitivity compensation unit is connected to the pressure sensing unit 10. The sensitivity compensation unit performs temperature compensation based on the sensitivity compensation signal.

[0032] As one embodiment, the sensitivity compensation unit includes a sixth resistor R6, a second capacitor C2, and a second operational amplifier A2. The input terminal of the second operational amplifier A2 is connected between the first resistor R1 and the fourth resistor R4. The first input terminal of the second operational amplifier A2 is connected to the output terminal of the second operational amplifier A2. The second input terminal of the second operational amplifier A2 is connected to the second output terminal of the control unit through the sixth resistor R6. The second input terminal of the second operational amplifier A2 is also connected to ground through the second capacitor C2.

[0033] The amplification unit is connected to the output terminals of the pressure sensing unit 10 and the zero-point compensation unit, respectively. The amplification unit amplifies the voltage signal and performs temperature compensation, and outputs a standard signal.

[0034] As one embodiment, the amplification unit includes an instrumentation amplifier PGA, the positive input terminal of which is connected between a third resistor R3 and a fourth resistor R4, and the negative input terminal of which is connected between a first resistor R1 and a second resistor R2.

[0035] It should be noted that, based on the circuit characteristics, the millivolt voltage signal output by the silicon piezoresistive pressure sensor is directly amplified and output through the instrumentation amplifier PGA. By using an instrumentation amplifier with a high slew rate or an operational amplifier with a high slew rate, the signal can be amplified without affecting the response time of the pressure sensor.

[0036] As one embodiment, the amplification unit is also connected to an adjustment resistor Rg so that the amplification factor can be adjusted by adjusting the resistor Rg.

[0037] It should be noted that, as Figure 1 As shown, the area within the dashed box is the high-frequency response, high-precision temperature compensation hybrid integrated unit 20 of the present invention, which mainly includes four units: an instrumentation amplifier (PGA), a control unit (MCU), a zero-point compensation PWM1+A1, and a sensitivity compensation PWM2+A2. This temperature compensation hybrid integrated circuit chip is designed with a VDD power supply positive pin and a GND power supply negative pin to power the internal instrumentation amplifier (PGA), control unit (MCU), and operational amplifier. Thus, by using a mature chip to fabricate a hybrid integrated circuit, there is no need to redesign and fabricate the chip, which shortens the development time and reduces the cost.

[0038] Furthermore, the temperature compensation hybrid integrated circuit of the silicon piezoresistive pressure sensor of the present invention can achieve multi-temperature point compensation with a temperature resolution of up to 0.5℃; the output path is fully analog, eliminating the need for AD and DA conversion, resulting in a very fast pressure response; based on the resistance temperature drift characteristics of the pressure sensor (silicon piezoresistive chip), the silicon piezoresistive chip is used as the temperature reference, eliminating the temperature field gradient problem between the pressure sensor (silicon piezoresistive chip) and the temperature compensation chip, ensuring high-precision output even when the product is handled in environments with rapid temperature changes (temperature change rate ≥ 10℃ / min).

[0039] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0041] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0043] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0044] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A temperature-compensated hybrid integrated circuit for a silicon piezoresistive pressure sensor, characterized in that, include: The pressure sensing unit includes a pressure-sensing bridge and a voltage-dividing resistor. The pressure-sensing bridge is connected to the voltage-dividing resistor. The pressure sensing unit is used to output a corresponding voltage signal when the pressure sensor senses pressure. A temperature compensation hybrid integrated unit is shown, which is connected to the pressure sensing unit. The temperature compensation hybrid integrated unit includes: The control unit has its input terminal connected to the pressure sensing unit. The control unit is used to acquire the voltage signal after voltage division by the voltage divider resistor, so as to obtain the temperature corresponding to the pressure sensor based on the voltage signal after voltage division, and output the corresponding zero-point compensation signal and sensitivity compensation signal based on the temperature. A zero-point compensation unit, the input of which is connected to the first output of the control unit, performs temperature compensation based on the zero-point compensation signal; A sensitivity compensation unit is provided, wherein the input terminal of the sensitivity compensation unit is connected to the second output terminal of the control unit, and the output terminal of the sensitivity compensation unit is connected to the pressure sensing unit. The sensitivity compensation unit performs temperature compensation based on the sensitivity compensation signal. An amplification unit is connected to the output terminals of the pressure sensing unit and the zero-point compensation unit, respectively. The amplification unit amplifies and compensates for the temperature of the voltage signal and outputs a standard signal. The zero-point compensation unit includes a fifth resistor, a first capacitor, and a first operational amplifier. The first input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier and is connected to the amplification unit. The second input terminal of the first operational amplifier is connected to the first output terminal of the control unit through the fifth resistor. The second input terminal of the first operational amplifier is also connected to ground through the first capacitor.

2. The temperature compensation hybrid integrated circuit for the silicon piezoresistive pressure sensor as described in claim 1, characterized in that, The voltage-sensing bridge includes a first resistor, a second resistor, a third resistor, and a fourth resistor, which are connected in series. The voltage divider resistor is connected between the second resistor and the third resistor.

3. The temperature compensation hybrid integrated circuit for the silicon piezoresistive pressure sensor as described in claim 2, characterized in that, The first input terminal of the control unit is connected between the voltage divider resistor and the pressure-sensing bridge to acquire the temperature of the silicon piezoresistive pressure sensor.

4. The temperature compensation hybrid integrated circuit of the silicon piezoresistive pressure sensor as described in claim 3, characterized in that, The second input terminal of the control unit is used to communicate with the outside world in order to write temperature compensation data.

5. The temperature compensation hybrid integrated circuit for the silicon piezoresistive pressure sensor as described in claim 4, characterized in that, The amplification unit includes an instrumentation amplifier, the positive input terminal of which is connected between the third resistor and the fourth resistor, and the negative input terminal of which is connected between the first resistor and the second resistor.

6. The temperature compensation hybrid integrated circuit of the silicon piezoresistive pressure sensor as described in claim 5, characterized in that, The sensitivity compensation unit includes a sixth resistor, a second capacitor, and a second operational amplifier. The output terminal of the second operational amplifier is connected between the first resistor and the fourth resistor. The first input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier. The second input terminal of the second operational amplifier is connected to the second output terminal of the control unit through the sixth resistor. The second input terminal of the second operational amplifier is also connected to ground through the second capacitor.

7. The temperature compensation hybrid integrated circuit of the silicon piezoresistive pressure sensor as described in claim 6, characterized in that, The amplification unit is also connected to an adjustment resistor so that the amplification factor can be adjusted via the adjustment resistor.

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