CN211013318U - Pressure sensor measuring circuit - Google Patents
Pressure sensor measuring circuit Download PDFInfo
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- CN211013318U CN211013318U CN201922290692.9U CN201922290692U CN211013318U CN 211013318 U CN211013318 U CN 211013318U CN 201922290692 U CN201922290692 U CN 201922290692U CN 211013318 U CN211013318 U CN 211013318U
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Abstract
The utility model relates to a pressure sensor measuring circuit, including wheatstone bridge circuit, differential input amplifier circuit, voltage follower circuit. The piezoresistive strain gauge is used as a bridge arm of a Wheatstone bridge, and when the pressure changes, the resistance value of the piezoresistive strain gauge changes, so that the output voltage of the bridge changes. The changed tiny voltage is amplified by the differential input amplifying circuit and then output by the voltage follower circuit. The utility model discloses the circuit is simple, job stabilization, and the line is brief.
Description
Technical Field
The utility model relates to a pressure sensor measuring circuit.
Background
The pressure sensor is a device for converting pressure into an electric signal, can be used for measuring water pressure, oil pressure, mechanical pressure and the like, and is widely applied to various intelligent devices. The silicon/germanium piezoresistive sensor belongs to one of the silicon/germanium piezoresistive sensor, and the conventional silicon/germanium piezoresistive sensor measuring circuit has the defects of more silicon/germanium strain gauges, complex measuring circuit, larger zero offset and difficulty in adjustment, so that a simple and convenient pressure sensor measuring circuit with stable work is required.
Disclosure of Invention
The utility model aims at overcoming the deficiencies of the prior art, providing a simple circuit, job stabilization, brief pressure sensor measuring circuit of line.
The technical scheme of the utility model is that:
a pressure sensor measuring circuit comprises a Wheatstone bridge circuit, a differential input amplifying circuit and a voltage follower circuit.
The Wheatstone bridge circuit detects pressure and converts the pressure into voltage, the output voltage of the bridge changes when the pressure changes, and the changed voltage is sent to the differential input amplifying circuit. The differential input amplifying circuit amplifies the changed tiny voltage, common mode interference can be effectively inhibited by adopting a differential input mode, and the amplified voltage signal is sent to the voltage follower circuit. And the voltage follower circuit is used for outputting the signals after the signals are isolated and buffered, so that the load capacity of the output signals is improved.
The Wheatstone bridge circuit comprises germanium strain gauges QT and QC which are used for respectively detecting expansion pressure and contraction pressure, wherein the QT and the QC are respectively connected in series with compensation resistors R4 and R5 to form a first branch, R4 and R5 change near 5 ohms to ensure that the resistance values of the QT and the QC are completely equal after compensation, the QT and the QC are connected with a D point, a 7.25K resistor R2 and a 10K resistor R3 are connected in series to form a second branch, R2 and R3 are connected with a C point, the first branch and the second branch are connected in parallel to form four bridge arms of the bridge, a connection point A of the resistor R2 and a resistor R4 is connected with a +5V power supply through a 25-ohm resistor R1, a connection point B of the resistor R3 and the resistor R5 is grounded through a 50-ohm resistor R6, the R1 and R6 are mainly used for adjusting the current magnitude of the bridge, the potential of the D point changes along with.
The differential input amplifying circuit comprises an operational amplifier U1A, and the voltage follower circuit comprises an operational amplifier U1B, U1A and U1B belong to a double-operational-amplifier integrated chip, such as L M358, but not limited to L M358.
The differential input amplifying circuit input signal comes from the output of the Wheatstone bridge circuit, the D point of the Wheatstone bridge circuit is connected to the No. 2 pin of the inverting input end of the operational amplifier U1A through the 5K resistor R7, the C point of the Wheatstone bridge circuit is directly connected to the No. 3 pin of the non-inverting input end of the operational amplifier U1A, the 350K resistor R8 is connected to the No. 1 pin of the output end of the operational amplifier U1A and the No. 2 pin of the inverting input end of the operational amplifier U1 1 in parallel to form a feedback branch, the capacitor C1 plays a role in phase compensation, the self-excitation phenomenon under the depth feedback is avoided, and the tiny voltage between the D point and the C point is amplified and then is output from the No. 1 pin of the.
The input signal of the voltage follower circuit comes from the output of the differential input amplifying circuit, the output of the voltage follower circuit is connected to the No. 5 pin of the non-inverting input end of the operational amplifier UIB, and the No. 6 pin of the inverting input end of the operational amplifier UIB is connected with the No. 7 pin of the output end.
The utility model discloses the advantage: the circuit has the advantages of less used circuit elements, short connecting line and simple circuit, and the compensation resistor, the bridge current adjusting resistor and the circuit follower circuit of the strain gauge are added, so that the work is stable.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and the detailed description.
As shown in FIG. 1, a pressure sensor measuring circuit includes a Wheatstone bridge circuit, a differential input amplifying circuit, and a voltage follower circuit.
The Wheatstone bridge circuit detects pressure and converts the pressure into voltage, the output voltage of the bridge changes when the pressure changes, and the changed voltage is sent to the differential input amplifying circuit. The differential input amplifying circuit amplifies the changed tiny voltage, common mode interference can be effectively inhibited by adopting a differential input mode, and the amplified voltage signal is sent to the voltage follower circuit. And the voltage follower circuit is used for outputting the signals after the signals are isolated and buffered, so that the load capacity of the output signals is improved.
The Wheatstone bridge circuit comprises germanium strain gauges QT and QC which are used for respectively detecting expansion pressure and contraction pressure, wherein the QT and the QC are respectively connected in series with compensation resistors R4 and R5 to form a first branch, R4 and R5 change near 5 ohms to ensure that the resistance values of the QT and the QC are completely equal after compensation, the QT and the QC are connected with a D point, a 7.25K resistor R2 and a 10K resistor R3 are connected in series to form a second branch, R2 and R3 are connected with a C point, the first branch and the second branch are connected in parallel to form four bridge arms of the bridge, a connection point A of the resistor R2 and a resistor R4 is connected with a +5V power supply through a 25-ohm resistor R1, a connection point B of the resistor R3 and the resistor R5 is grounded through a 50-ohm resistor R6, the R1 and R6 are mainly used for adjusting the current magnitude of the bridge, the potential of the D point changes along with.
The differential input amplifying circuit comprises an operational amplifier U1A, and the voltage follower circuit comprises an operational amplifier U1B, U1A and U1B belong to a double-operational-amplifier integrated chip, such as L M358, but not limited to L M358.
The differential input amplifying circuit input signal comes from the output of the Wheatstone bridge circuit, the D point of the Wheatstone bridge circuit is connected to the No. 2 pin of the inverting input end of the operational amplifier U1A through the 5K resistor R7, the C point of the Wheatstone bridge circuit is directly connected to the No. 3 pin of the non-inverting input end of the operational amplifier U1A, the 350K resistor R8 is connected to the No. 1 pin of the output end of the operational amplifier U1A and the No. 2 pin of the inverting input end of the operational amplifier U1 1 in parallel to form a feedback branch, the capacitor C1 plays a role in phase compensation, the self-excitation phenomenon under the depth feedback is avoided, and the tiny voltage between the D point and the C point is amplified and then is output from the No. 1 pin of the.
The input signal of the voltage follower circuit comes from the output of the differential input amplifying circuit, the output of the voltage follower circuit is connected to the No. 5 pin of the non-inverting input end of the operational amplifier UIB, and the No. 6 pin of the inverting input end of the operational amplifier UIB is connected with the No. 7 pin of the output end.
The present invention has been disclosed in the foregoing with reference to the preferred embodiments, but it is not intended to limit the present invention, and all technical solutions obtained by the equivalent replacement or equivalent replacement are within the scope of the present invention.
Claims (5)
1. A pressure sensor measuring circuit comprises a Wheatstone bridge circuit, a differential input amplifying circuit and a voltage follower circuit, and is characterized in that the Wheatstone bridge circuit detects pressure and converts the pressure into voltage, the bridge output voltage changes when the pressure changes and sends the changed voltage to the differential input amplifying circuit, the differential input amplifying circuit amplifies the changed tiny voltage, common-mode interference can be effectively inhibited by adopting a differential input mode, an amplified voltage signal is sent to the voltage follower circuit, and the voltage follower circuit outputs the signal after isolation and buffering, so that the load capacity of the output signal is improved.
2. The pressure sensor measuring circuit of claim 1, wherein the wheatstone bridge circuit comprises germanium strain gauges QT and QC for respectively detecting the expansion pressure and the contraction pressure, the QT and QC are respectively connected in series with compensation resistors R4 and R5 and then connected in series to form a first branch, R4 and R5 are changed around 5 ohms to ensure that the resistance values of QT and QC are completely equal after compensation, the QT and QC are connected to a point D, a 7.25K resistor R2 and a 10K resistor R3 are connected in series to form a second branch, R2 and R3 are connected to a point C, the first branch and the second branch are connected in parallel to form four arms of the bridge, a connection point a between the resistor R2 and the resistor R4 is connected to a +5V power supply through a 25 ohm resistor R1, a connection point B between the resistor R3 and the resistor R5 is connected to the ground through a 50 ohm resistor R6, the R1 and R6 are mainly used for adjusting the current magnitude of the bridge, the potential of the point D changes with the pressure, and the output end of the wheatstone bridge is.
3. The pressure sensor measuring circuit of claim 1, wherein the differential input amplifying circuit comprises an operational amplifier U1A, the voltage follower circuit comprises an operational amplifier U1B, and U1A and U1B belong to a dual operational amplifier integrated chip.
4. The pressure sensor measuring circuit of claim 1, wherein the differential input amplifying circuit input signal is from the output of the wheatstone bridge circuit, the point D of the wheatstone bridge circuit is connected to the pin No. 2 of the inverting input terminal of the operational amplifier U1A through a 5K resistor R7, the point C of the wheatstone bridge circuit is directly connected to the pin No. 3 of the non-inverting input terminal of the operational amplifier U1A, a 350K resistor R8 is connected to the pin No. 1 of the output terminal and the pin No. 2 of the inverting input terminal of the operational amplifier U1A after being connected in parallel with a 10 μ F capacitor C1 to form a feedback branch, and a tiny voltage between the point D and the point C is amplified and then output from the pin No. 1 of the output terminal of the operational amplifier U1A.
5. The pressure sensor measuring circuit of claim 1, wherein the voltage follower circuit input signal is from the output of the differential input amplifier circuit, the output of the voltage follower circuit input signal is connected to pin 5 of the non-inverting input of the operational amplifier UIB, and pin 6 of the inverting input of the operational amplifier UIB is connected to pin 7 of the output.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922290692.9U CN211013318U (en) | 2019-12-19 | 2019-12-19 | Pressure sensor measuring circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922290692.9U CN211013318U (en) | 2019-12-19 | 2019-12-19 | Pressure sensor measuring circuit |
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| CN211013318U true CN211013318U (en) | 2020-07-14 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201922290692.9U Active CN211013318U (en) | 2019-12-19 | 2019-12-19 | Pressure sensor measuring circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113865757A (en) * | 2021-09-16 | 2021-12-31 | 歌尔微电子股份有限公司 | Detection circuit and detection method of piezoresistive pressure sensor and electronic equipment |
| CN114563127A (en) * | 2021-11-30 | 2022-05-31 | 重庆湃芯创智微电子有限公司 | Calibration method for zero position and sensitivity of invasive blood pressure sensing chip |
-
2019
- 2019-12-19 CN CN201922290692.9U patent/CN211013318U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113865757A (en) * | 2021-09-16 | 2021-12-31 | 歌尔微电子股份有限公司 | Detection circuit and detection method of piezoresistive pressure sensor and electronic equipment |
| CN114563127A (en) * | 2021-11-30 | 2022-05-31 | 重庆湃芯创智微电子有限公司 | Calibration method for zero position and sensitivity of invasive blood pressure sensing chip |
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