CN219495522U - Piezoresistive pressure sensor detection circuit - Google Patents
Piezoresistive pressure sensor detection circuit Download PDFInfo
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- CN219495522U CN219495522U CN202320313421.4U CN202320313421U CN219495522U CN 219495522 U CN219495522 U CN 219495522U CN 202320313421 U CN202320313421 U CN 202320313421U CN 219495522 U CN219495522 U CN 219495522U
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Abstract
The utility model discloses a piezoresistive pressure sensor detection circuit which comprises a constant voltage circuit unit, a piezoresistive pressure sensor, a reference power supply unit, a three operational amplifier instrument amplifier, an analog-to-digital conversion unit and a microprocessor, wherein the piezoresistive pressure sensor adopts a Wheatstone bridge structure, and the reference power supply unit comprises a voltage follower U3; the output end of the constant voltage circuit unit is connected with the input end of the piezoresistive pressure sensor, and the output end of the piezoresistive pressure sensor is connected with the input end of the three operational amplifier instrument amplifier; the output end of the constant voltage circuit unit is connected with the non-inverting input end of the voltage follower U3 after the reference voltage is obtained through the voltage division of the resistor R5 and the resistor R8, the inverting input end of the voltage follower U3 is connected with the output end and the first input end of the three operational amplifier instrument amplifier and the analog-digital conversion unit, and the output end of the analog-digital conversion unit is connected with the input end of the microprocessor. The utility model can be widely applied to various piezoresistive pressure sensor signal detection occasions.
Description
Technical Field
The utility model relates to the technical field of pressure sensors, in particular to a piezoresistive pressure sensor detection circuit.
Background
The piezoresistive pressure sensor has the advantages of high precision, high sensitivity, quick frequency response, small volume, high reliability and the like, and is widely applied to various fields of aerospace, aviation, navigation, chemical industry, electric power, medical treatment, weather, water conservancy, geology and the like. The piezoresistive pressure sensor is divided into a constant current source excitation pressure sensor and a constant voltage source excitation pressure sensor according to different temperature compensation modes of the piezoresistive bridge.
Under the excitation condition of the constant current source, the input impedance of the pressure-resistance pressure sensor is influenced, the power supply voltage of the power supply loop is required to be larger than the working voltage of the pressure sensor in the constant current mode, the recommended value of the constant current power supply current of the pressure sensor is 1mA, the input impedance is about 4KΩ, the working voltage is about 4V, and the 5V power supply system is suitable for the analog acquisition circuit in consideration of the voltage allowance.
However, at present, the detection instrument is more and more miniaturized and convenient, and the detection instrument in a 3.7V lithium battery power supply mode is more and more popular, and if the lithium battery is adopted to supply power to the piezoresistive pressure sensor in a constant current mode, the voltage value of the piezoresistive pressure sensor can meet the working requirement of the pressure sensor only through a DC-DC boost conversion circuit with lower conversion efficiency; in the constant current source mode, the battery utilization efficiency is low, and in order to improve the battery utilization efficiency, a power supply mode of a constant voltage source is adopted to provide excitation for the pressure sensor, so that the technology development trend is more met.
Disclosure of Invention
In order to solve the above problems, an object of the present utility model is to provide a piezoresistive pressure sensor detection circuit.
In order to achieve the aim of the utility model, the utility model adopts the following technical scheme:
the piezoresistive pressure sensor detection circuit comprises a constant voltage circuit unit, a piezoresistive pressure sensor, a reference power supply unit, a three operational amplifier instrument amplifier, an analog-to-digital conversion unit and a microprocessor, wherein the piezoresistive pressure sensor adopts a Wheatstone bridge structure, and the reference power supply unit comprises a voltage follower U3; the output end of the constant voltage circuit unit is connected with the input end of the piezoresistive pressure sensor, and the output end of the piezoresistive pressure sensor is connected with the input end of the three operational amplifier instrument amplifiers; the output end of the constant voltage circuit unit is connected with the non-inverting input end of the voltage follower U3 after the reference voltage is obtained through the voltage division of the resistor R5 and the resistor R8, the inverting input end of the voltage follower U3 is connected with the output end and the first input end of the three operational amplifier instrument amplifier and the analog-digital conversion unit, and the output end of the analog-digital conversion unit is connected with the input end of the microprocessor.
Further, the constant voltage circuit unit includes a voltage stabilizing source U1 and an operational amplifier U2, where the dc power VCC is connected to the cathode of the voltage stabilizing source U1 and the non-inverting input terminal of the operational amplifier U2 through a resistor R6, and the reference electrode of the voltage stabilizing source U1 is connected to the non-inverting input terminal of the operational amplifier U2 through a resistor R7 and a capacitor C2 connected in parallel, and is connected to the anode through a resistor R9 and grounded; the inverting input end of the operational amplifier U2 is connected with the output end and is connected with the positive input end of the piezoresistive pressure sensor and the input end of the reference power supply unit.
Further, the piezoresistive pressure sensor is a wheatstone bridge structure composed of four pressure strain gauges, and comprises a pressure strain gauge R1, a pressure strain gauge R2, a pressure strain gauge R4 and a pressure strain gauge R3 which are connected end to end in sequence, wherein the output end of the constant voltage circuit unit is electrically connected between the pressure strain gauge R1 and the pressure strain gauge R3, and the pressure strain gauge R2 and the pressure strain gauge R4 are indirectly grounded; the first output end is used between the pressure strain gauge R3 and the pressure strain gauge R4, the second output end is used between the pressure strain gauge R1 and the pressure strain gauge R2, and the three operational amplifier instrument amplifiers are all electrically connected.
Further, the three operational amplifier instrument amplifier comprises an operational amplifier U4, an operational amplifier U5 and an operational amplifier U6, wherein the non-inverting input ends of the operational amplifier U4 and the operational amplifier U6 are respectively connected with a first output end and a second output end of the piezoresistive pressure sensor, a resistor R13 is connected between the inverting input ends of the operational amplifier U4 and the operational amplifier U6, the inverting input end of the operational amplifier U4 is connected with the output end through a resistor R12 and is connected with the non-inverting input end of the operational amplifier U5 through a resistor R10, and the inverting input end of the operational amplifier U6 is connected with the output end through a resistor R14 and is connected with the inverting input end of the operational amplifier U5 through a resistor R15; the non-inverting input end of the operational amplifier U5 is connected with the output end of the voltage follower U3 of the reference power supply unit and the first negative input end of the analog-to-digital conversion unit through a resistor R11, and the inverting input end is connected with the output end through a resistor R16 and the first positive input end of the analog-to-digital conversion unit.
Further, the second input end of the analog-to-digital conversion unit is connected with the ambient temperature monitoring unit.
Furthermore, the output end of the microprocessor is also connected with the RS485 communication unit and the display unit.
By adopting the technical scheme, the utility model has the following advantages:
the piezoresistive pressure sensor detection circuit utilizes a voltage stabilizing source of a constant voltage circuit unit to be matched with a resistor and a follower of a reference power supply unit to provide a high-precision constant voltage excitation power supply for the piezoresistive pressure sensor, utilizes the reference power supply unit to realize the control of differential signal output voltage, and utilizes a three-operational amplifier instrument amplifier to differentially amplify differential voltage signals output by the piezoresistive pressure sensor; the pressure sensor has the advantages of simple structure, low cost, high precision, wide temperature range and high stability, and can be widely applied to various piezoresistive pressure sensor signal detection occasions.
Drawings
FIG. 1 is a schematic diagram of a piezoresistive pressure sensor detection circuit according to the present utility model.
Description of the embodiments
The technical scheme of the utility model is further described in detail below with reference to the accompanying drawings and examples.
As shown in fig. 1, the piezoresistive pressure sensor detection circuit comprises a constant voltage circuit unit, a piezoresistive pressure sensor, a reference power supply unit, a three-operational amplifier, an analog-to-digital conversion unit and a microprocessor, wherein the constant voltage circuit unit comprises a voltage stabilizing source U1 and an operational amplifier U2, a direct current power supply VCC is connected with a cathode of the voltage stabilizing source U1 and a non-inverting input end of the operational amplifier U2 through a resistor R6, a reference electrode of the voltage stabilizing source U1 is connected with the non-inverting input end of the operational amplifier U2 through a resistor R7 and a capacitor C2 which are connected in parallel, and is connected with an anode of the voltage stabilizing source U1 through a resistor R9 and grounded; the inverting input end of the operational amplifier U2 is connected with the output end and is connected with the positive input end of the piezoresistive pressure sensor and the input end of the reference power supply unit; the piezoresistive pressure sensor adopts a Wheatstone bridge (Wheatstone bridge) structure formed by four pressure strain gauges, and comprises a pressure strain gauge R1, a pressure strain gauge R2, a pressure strain gauge R4 and a pressure strain gauge R3 which are sequentially connected end to end, wherein each pressure strain gauge is a pressure strain gauge with resistance changing along with pressure, the output end of the operational amplifier U2 is electrically connected between the pressure strain gauge R1 and the pressure strain gauge R3, and the pressure strain gauge R2 and the pressure strain gauge R4 are indirectly grounded; the first output end is used between the pressure strain gauge R3 and the pressure strain gauge R4, the second output end is used between the pressure strain gauge R1 and the pressure strain gauge R2, and the three operational amplifier instrument amplifiers are electrically connected; the reference power supply unit comprises a voltage follower U3, wherein the non-inverting input end of the voltage follower U3 is connected with the output end of the operational amplifier U2 after the non-inverting input end of the voltage follower U3 is divided by a resistor R5 and a resistor R8 to obtain the required reference voltage, and the inverting input end of the voltage follower U3 is connected with the output end and is connected with a three-operational amplifier instrument amplifier and a first negative input end (AINN) of the analog-to-digital conversion unit; the three operational amplifier instrument amplifier comprises an operational amplifier U4, an operational amplifier U5 and an operational amplifier U6, wherein non-inverting input ends of the operational amplifier U4 and the operational amplifier U6 are respectively connected with a first output end and a second output end of a piezoresistive pressure sensor, a resistor R13 is connected between inverting input ends of the operational amplifier U4 and the operational amplifier U6, the inverting input end of the operational amplifier U4 is connected with the output end through a resistor R12 and is connected with the non-inverting input end of the operational amplifier U5 through a resistor R10, and the inverting input end of the operational amplifier U6 is connected with the output end through a resistor R14 and is connected with the inverting input end of the operational amplifier U5 through a resistor R15; the non-inverting input end of the operational amplifier U5 is connected with the output end of the voltage follower U3 of the reference power supply unit and the first negative input end (AINN) of the analog-to-digital conversion unit through a resistor R11, and the inverting input end is connected with the output end through a resistor R16 and the first positive input end (AINP) of the analog-to-digital conversion unit.
The second input end of the analog-to-digital conversion unit is connected with the ambient temperature monitoring unit and is used for correcting the ambient temperature of the piezoresistive pressure sensor, so that accurate measurement of the pressure at different temperatures is realized.
The output end of the microprocessor is also connected with the display unit and the RS485 communication unit, the pressure value corrected by the microprocessor is transmitted to other equipment through the RS485 communication unit, and the pressure value corrected by the microprocessor is displayed on the display screen through the display unit.
In the above constant voltage circuit unit, the model of the constant voltage source U1 is TL431, and the model of the operational amplifier U2 is GS8551-TR.
In the reference power supply unit, the voltage follower U3 is selected from the models GS8551-TR.
In the three operational amplifier instrument amplifiers, the model numbers of the operational amplifier U4, the operational amplifier U5 and the operational amplifier U6 are GS8551-TR.
The model of the analog-to-digital conversion chip selected by the analog-to-digital conversion unit is CS1232-TS.
The model of the microprocessor is APM32F103RET6.
The utility model relates to a piezoresistive pressure sensor detection circuit, which has the following working principle: the constant voltage source U1 of the constant voltage circuit unit provides constant and precise constant voltage power for the piezoresistive pressure sensor, and the bridge output voltage of the piezoresistive pressure sensor is
In piezoresistive pressure sensors: r1=r4=r0- Δr; r2=r3=r0+Δr; r0 is zero resistance of piezoresistive pressure sensor, which is pressureResistance change of the resistor after pressure sensing of the resistive pressure sensor
The three operational amplifier instrument amplifiers perform differential amplification on a voltage differential signal output by the piezoresistive pressure sensor, wherein R12=R14; r10=r15; r11=r16; the magnification is as follows:
the differential output voltage value of the three operational amplifier instrument amplifier is as follows:
the control of the differential signal output voltage by using the reference power supply unit is specifically as follows: the voltage value is obtained through two voltage dividing resistors, namely a resistor R5 and a resistor R8, and then the obtained voltage value is reduced in output impedance through a voltage follower U3 for the three operational amplifier instrument amplifier to ensure that the voltage value is usedThe voltage output ranges of the analog-to-digital conversion units are all within the voltage input range of the analog-to-digital conversion units.
The analog-to-digital conversion unit converts the voltage signal output by the front-end analog circuit into a digital signal which can be identified by the microprocessor, and transmits the digital signal to the microprocessor through corresponding digital interfaces such as SPI, IIC and the like; the microprocessor obtains the values of the linear relation curve coefficients k and b between the digital signal sampling value and the pressure value through calibration, and after the calibration is finished, the pressure value at the time can be calculated according to the k, the b and the read digital signal sampling value; and then carrying out temperature correction on the pressure value according to the detected ambient temperature value.
The above description is only of the preferred embodiments of the present utility model and is not intended to limit the present utility model, but various modifications and variations can be made to the present utility model by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model should be included in the protection scope of the present utility model.
Claims (6)
1. A piezoresistive pressure sensor detection circuit is characterized in that: the piezoresistive pressure sensor comprises a constant voltage circuit unit, a piezoresistive pressure sensor, a reference power supply unit, a three-operational-amplifier instrument amplifier, an analog-to-digital conversion unit and a microprocessor, wherein the piezoresistive pressure sensor adopts a Wheatstone bridge structure, and the reference power supply unit comprises a voltage follower U3; the output end of the constant voltage circuit unit is connected with the input end of the piezoresistive pressure sensor, and the output end of the piezoresistive pressure sensor is connected with the input end of the three operational amplifier instrument amplifiers; the output end of the constant voltage circuit unit is connected with the non-inverting input end of the voltage follower U3 after the reference voltage is obtained through the voltage division of the resistor R5 and the resistor R8, the inverting input end of the voltage follower U3 is connected with the output end and the first input end of the three operational amplifier instrument amplifier and the analog-digital conversion unit, and the output end of the analog-digital conversion unit is connected with the input end of the microprocessor.
2. The piezoresistive pressure sensor detection circuit according to claim 1, wherein: the constant voltage circuit unit comprises a voltage stabilizing source U1 and an operational amplifier U2, wherein a direct current power supply VCC is connected with a cathode of the voltage stabilizing source U1 and a non-inverting input end of the operational amplifier U2 through a resistor R6, a reference electrode of the voltage stabilizing source U1 is connected with the non-inverting input end of the operational amplifier U2 through a resistor R7 and a capacitor C2 which are connected in parallel, and is connected with an anode through a resistor R9 and is grounded; the inverting input end of the operational amplifier U2 is connected with the output end and is connected with the positive input end of the piezoresistive pressure sensor and the input end of the reference power supply unit.
3. The piezoresistive pressure sensor detection circuit according to claim 1, wherein: the piezoresistive pressure sensor is a Wheatstone bridge structure composed of four pressure strain gauges, and comprises a pressure strain gauge R1, a pressure strain gauge R2, a pressure strain gauge R4 and a pressure strain gauge R3 which are connected end to end in sequence, wherein the output end of the constant voltage circuit unit is electrically connected between the pressure strain gauge R1 and the pressure strain gauge R3, and the pressure strain gauge R2 and the pressure strain gauge R4 are indirectly grounded; the first output end is used between the pressure strain gauge R3 and the pressure strain gauge R4, the second output end is used between the pressure strain gauge R1 and the pressure strain gauge R2, and the three operational amplifier instrument amplifiers are all electrically connected.
4. The piezoresistive pressure sensor detection circuit according to claim 1, wherein: the operational amplifier comprises an operational amplifier U4, an operational amplifier U5 and an operational amplifier U6, wherein the non-inverting input ends of the operational amplifier U4 and the operational amplifier U6 are respectively connected with a first output end and a second output end of the piezoresistive pressure sensor, a resistor R13 is connected between the inverting input ends of the operational amplifier U4 and the operational amplifier U6, the inverting input end of the operational amplifier U4 is connected with the output end through a resistor R12 and is connected with the non-inverting input end of the operational amplifier U5 through a resistor R10, and the inverting input end of the operational amplifier U6 is connected with the output end through a resistor R14 and is connected with the inverting input end of the operational amplifier U5 through a resistor R15; the non-inverting input end of the operational amplifier U5 is connected with the output end of the voltage follower U3 of the reference power supply unit and the first negative input end of the analog-to-digital conversion unit through a resistor R11, and the inverting input end is connected with the output end through a resistor R16 and the first positive input end of the analog-to-digital conversion unit.
5. The piezoresistive pressure sensor detection circuit according to claim 1, wherein: the second input end of the analog-to-digital conversion unit is connected with the ambient temperature monitoring unit.
6. The piezoresistive pressure sensor detection circuit according to claim 1, wherein: the output end of the microprocessor is also connected with the RS485 communication unit and the display unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320313421.4U CN219495522U (en) | 2023-02-25 | 2023-02-25 | Piezoresistive pressure sensor detection circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320313421.4U CN219495522U (en) | 2023-02-25 | 2023-02-25 | Piezoresistive pressure sensor detection circuit |
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| Publication Number | Publication Date |
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| CN219495522U true CN219495522U (en) | 2023-08-08 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202320313421.4U Active CN219495522U (en) | 2023-02-25 | 2023-02-25 | Piezoresistive pressure sensor detection circuit |
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| CN (1) | CN219495522U (en) |
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- 2023-02-25 CN CN202320313421.4U patent/CN219495522U/en active Active
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