CN105973509A - Pressure transducer circuit and commissioning method thereof - Google Patents
Pressure transducer circuit and commissioning method thereof Download PDFInfo
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- CN105973509A CN105973509A CN201610296426.5A CN201610296426A CN105973509A CN 105973509 A CN105973509 A CN 105973509A CN 201610296426 A CN201610296426 A CN 201610296426A CN 105973509 A CN105973509 A CN 105973509A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
- G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
- G01L1/225—Measuring circuits therefor
- G01L1/2262—Measuring circuits therefor involving simple electrical bridges
Abstract
The invention belongs to the pressure sensing technology and provides a pressure transducer circuit and a commissioning method thereof. The pressure transducer circuit comprises four parts including a circuit voltage reference circuit (1), a sensitive electrical bridge (2), a voltage amplifier circuit (3) and a current conversion circuit (4). The pressure transducer circuit, by reasonably selecting voltage reference, operational amplifier and other mainly devices, reduces supply voltage of a Wheatstone pressure sensitive electrical bridge and increases the resistance of a zero voltage dividing adjusting resistor, so that the static consumption current of the transducer signal conditioning circuit is no greater than 3.8mA, and the commissioning requirement of the pressure transducer is satisfied. High magnification of weak signals of a pressure sensitive electrical bridge is realized through reasonably determining the amplification times of a three op-amp instrumentation amplification circuit and the capacity of parallel porcelain capacitors on a negative feedback resistor of a voltage amplifier circuit, and the circuit is provided with excellent stability.
Description
Technical field
The invention belongs to pressure sensing technology, relate to a kind of pressure sensor circuit and adjustment method thereof.
Background technology
Pressure transducer uses two-wire system 4mA～20mA normalized current ring design, it is possible to achieve telecommunications
Number long-distance transmissions, have signal transmission accurately, strong, static to consume electric current low for capacity of resisting disturbance
Advantage；Two-wire system design simultaneously is effectively reduced between pressure transducer and system electrical connection electricity
The quantity of cable.The pressure transducer of two-wire system 4mA～20mA output necessarily requires pressure transducer
Circuit static consumes electric current and should be less than 3.8mA, otherwise cannot debug.
Pressure transducer is quick frequently with sputtered film presser sensor principle or titanium/silicon-on-sapphire pressure
The pressure sensitive core of sense principle, above-mentioned sensitivity principle is that the deformation by flexible sheet causes pressure
Sensitive electric bridge arm resistance change, thus realize being converted to pressure signal the purpose of resistance signal.
The distinguishing feature of the pressure sensitive core sensitivity electric bridge of these principles has: 1) sensitivity is low, the fullest
Range output is only 1mV/V～3mV/V；2) the arm resistance value of sensitive electric bridge is usually 2.5k Ω
To 5k Ω.Pressure based on sputtered film presser sensor principle or sapphire pressure sensitivity principle passes
, there is following contradiction: in order to subtract in sensor two-wire system 4mA to be realized～the design requirement of 20mA output
The static of little pressure sensor circuit consumes electric current, needs to use the device of low consumption electric current in circuit,
Reduce the supply voltage of sensitive electric bridge the most as far as possible；But when reducing the supply voltage of sensitive electric bridge
Time, its output signal reduces therewith, in order to realize the output of 4mA～20mA current signal, needs to carry
The amplification of high circuit, its amplification typically requires and reaches 1000 times of multiples the most higher.
After amplification improves, its bridge output signal becomes more sensitive to faint circuit noise,
Cause exporting saltus step and unstable phenomenon, it is impossible to meet the design requirement of pressure transducer.
Summary of the invention
It is an object of the invention to: provide and a kind of static consume that electric current is low, capacity of resisting disturbance strong, stable
Pressure sensor circuit that property is good and adjustment method thereof.
The technical scheme that the present invention takes is: a kind of pressure sensor circuit, including voltage reference electricity
Road 1, sensitive electric bridge 2, voltage amplifier circuit 3, current converter circuit 4 four part, wherein, pressure
Force transducer includes electrical node VCC, IOUT、SGND、V+、Vref、Earth、+Vin、-Vin
And Vout；Voltage reference circuit 1 and node VCC, IOUT, SGND, V+, Vref and Earth
Being connected, sensitive electric bridge 2 is connected with voltage reference circuit 1 by node SGND, V+, sensitive
Electric bridge 2 is connected with voltage amplifier circuit 3 by node+Vin ,-Vin, and voltage amplifier circuit 3 leads to
Crossing node V+, SGND, Vref to be connected with voltage reference circuit 1, voltage amplifier circuit 3 passes through
Node Vout is connected with current converter circuit 4, and current converter circuit 4 is by node V+, SGND
It is connected with voltage reference circuit 1, wherein, described electrical node VCC, IOUT、SGND、V+、
The electrical Location of Vref, Earth ,+Vin ,-Vin, Vout is respectively the power supply input of pressure transducer
End, the current output terminal of pressure transducer, signal ground, the outfan of voltage reference circuit, zero-bit
Debugging voltage output end, shielding ground, the positive input terminal of voltage amplifier circuit 3, voltage amplifier circuit 3
Negative input end, the outfan of voltage amplifier circuit 3.
Described operational amplifier N2A, N2B, N2C and N2D select low-power consumption four-way computing to put
Big device.Voltage reference circuit 1 should select the voltage reference device of low-power consumption.
The output voltage amplitude of voltage reference circuit 1 determines by the following method: Uo ＜ 3.8-I1-I2?
×RB.Wherein Uo is the output voltage of voltage reference, RBThe minimum internal resistance value of sensitive electric bridge 2,
I1Maximum static for four-way operational amplifier consumes electric current, I2For setting the maximum static of voltage reference
Consume electric current.
Described fixed resister R2, R3, R4 ... R13, R14 select the resistor of low inductance
Part, wherein resistance value R3=R4≤50k Ω, R5=R6=R7=R8 >=10k Ω, R9=R10,
R11=R12, should meet R13≤0.1% × R11, and R13 >=100 Ω.
The computational methods determining checking for zero benchmark fixed resister R2 resistance value span are:
R2 >=3.8-I1-I2-Uo/RB?.
According to the resistance value of each fixed resister preset in current converter circuit 4, calculate voltage and put
The magnitude of voltage Uout of big circuit 3 output end vo ut, computational methods are: Uout=(IOMAX×R13)
×R9/R12.Wherein IOMAXMaximum output current amplitude for pressure transducer.
Amplification A=Uout/ (Vs × Uo) of voltage amplifier circuit 3, wherein presser sensor electric bridge
Output voltage sensitivity be Vs, amplification A of voltage amplifier circuit 3 should be not more than 150；
If amplification A of voltage amplifier circuit 3 is unsatisfactory for requirement, then should again change electric current conversion
The resistance value that in circuit 4, fixed resister is preset, method particularly includes: keep R11, R12, R13
Resistance value constant, synchronize reduce R9, R10 resistance value, until making voltage amplifier circuit 3
Amplification A≤150.
Maximum input offset current I according to operational amplifierBWith maximum input bias current IOS, with
And the minimum zero-bit output voltage U of sensitivity electric bridgeBMIN, determine that amplification adjusts resistor R100
Maximum occurrences scope.Computational methods are as follows: R100≤UBMIN/(IB+IOS)。
When debugging, the output of presser sensor electric bridge being maintained at zero-bit output, keeping R100 is
Big value is constant, adjusts the resistance of R200, and the output current value making pressure sensor circuit is 4mA,
Observe the saltus step situation of current value.Under these conditions, by the capacitance of ceramic capacitor C3, C4
From 0.01uF gradually, until after output is stable, being further continued for the capacitance of C3, C4 is increased 50%,
Final value as C3, C4 capacitance.
The adjustment method of pressure sensor circuit, detailed process is as follows: step 1, selection voltage reference
Low-power consumption accurate device operational amplifier and voltage reference in circuit 1, the sensitive electric bridge 2 of step 2, mensuration
Minimum internal resistance value, step 3, determines the output voltage amplitude of voltage reference in voltage reference circuit 1,
Step 4, determine the resistance value of checking for zero benchmark fixed resister in voltage reference circuit 1, pass through
Step 1,2,3,4 main devices determined respectively, pressure benchmark output voltage amplitude span,
The span of checking for zero benchmark fixed resister R2 resistance value, it is ensured that pressure sensor circuit
The static electric current that consumes, less than 3.8mA, meets the commissioning requirements of pressure transducer；Step 5, preset electricity
In stream change-over circuit 4, the resistance value of fixed resister, makes voltage signal amplify the most accurate, improves electricity
The output impedance of stream change-over circuit 4；Step 6, the voltage of calculating voltage amplifier circuit 3 output end vo ut
Value, step 7, determines the amplification of voltage amplifier circuit 3, step 8, determines voltage amplifier circuit
In 3, amplification adjusts the maximum occurrences of resistor, is used in step 9, selected voltage amplifier circuit 3
The resistance value span of the negative feedback fixed resister of two operational amplifiers of differential amplification, logical
Cross step 6,7,8,9 realize amplification in voltage amplifier circuit 3 adjust resistor maximum occurrences,
Voltage amplifier circuit 3 is used for the negative feedback fixed resister of two operational amplifiers of differential amplification
Resistance value span, make operational amplifier be operated in optimum state, reduce due to operation amplifier
The impact that small-signal is amplified by the input offset current of device and bias current, improves and amplifies voltage
Stability；The resistance value of remaining fixed resister in step 10, selected voltage amplifier circuit 3；Step
11, the negative feedback electric capacity of two operational amplifiers for differential amplification in voltage amplifier circuit 3 is determined
The capacitance of device, to ensure that amplifying circuit 3 is operated in steady statue, it is to avoid the fluctuation of output voltage and
Affect the output of pressure transducer；Step 12, determine the parameter of other components and parts in circuit；Step
13, adjust in voltage reference circuit 1 and checking for zero rheostat and voltage amplifier circuit 3 amplify
Multiple adjusts the resistance value of resistor, makes to export during zero-bit output and the maximum pressure of pressure transducer
Value meets requirement.
The present invention has and provides the benefit that: pressure transducer of the present invention include circuit voltage reference circuit 1,
Sensitive electric bridge 2, voltage amplifier circuit 3, current converter circuit 4 four part.This pressure transducer electricity
Road, by rationally selecting the main devices such as voltage reference, operational amplifier, reduces wheatstone pressure quick
The supply voltage of inductance bridge, increase total null voltage dividing potential drop adjust the resistance of resistor, make sensor believe
The static electric current that consumes of number modulate circuit is not more than 3.8mA, thus meets the debugging of pressure transducer
Requirement；By rationally determining the amplification of three amplifier magnifiers, determining voltage amplification
The capacity of the ceramic capacitor in parallel in degeneration resistors in circuit, it is achieved to presser sensor electric bridge
The high multiple of small-signal amplifies, and makes circuit have stability well simultaneously.The present invention provides
Pressure sensor circuit and adjustment method thereof, it is possible to achieve low to sputtered film presser sensor electric bridge etc.
The amplification of sensitivity sensitive electrical bridge output signal, it is achieved 4mA～20mA two-wire system standard current signal
Output, has static consumption electric current little, working stability, the feature that precision is high.
Accompanying drawing explanation
Fig. 1 is pressure sensor circuit structural representation of the present invention；
Fig. 2 is pressure transducer adjustment method flow chart of the present invention；
Wherein: 1 voltage reference circuit, 2 sensitive electric bridges, 3 voltage amplifier circuits, 4 electricity
Stream change-over circuit.
Detailed description of the invention
Below in conjunction with Figure of description 1, the present invention is described in further detail.
As it is shown in figure 1, pressure sensor circuit includes voltage reference circuit 1, sensitive electric bridge 2, electricity
Pressure amplifying circuit 3, current converter circuit 4 four part；Pressure sensor circuit includes electrical node
VCC、IOUT, SGND, V+, Vref, Earth ,+Vin ,-Vin and Vout；Voltage reference electricity
Road 1 and node VCC, IOUT, SGND, V+, Vref be connected with Earth, sensitive electric bridge 2
Be connected with voltage reference circuit 1 by node SGND, V+, sensitive electric bridge 2 by node+Vin,
-Vin is connected with voltage amplifier circuit 3, voltage amplifier circuit 3 by node V+, SGND,
Vref is connected with voltage reference circuit 1, and voltage amplifier circuit 3 is changed with electric current by node Vout
Circuit 4 connects, and current converter circuit 4 is by node V+, SGND with voltage reference circuit 1 even
Connect.
Voltage reference circuit 1 is power-switching circuit, including three end filter Z1 and Z2, switch
Diode D1, fixed resister R1 and R2, transient voltage suppressor D2, capacitor C1,
C2 and C3, voltage reference N1, adjustable resistor R200.Voltage reference circuit 1 comprises six electricity
Moral point source anode VCC, current output terminal IOUT, signal ground SGND, voltage reference output
End V+, zero-bit adjustable voltage Vref and shielding ground Earth.The input of three end filter Z1 connects
The positive terminal of the outfan connecting valve diode D1 of node VCC, three end filter Z1；Three ends
The outfan of wave filter Z2 connects IOUT；The earth terminal of three end filter Z1, Z2 all with node Earth
Connect；The negative pole end of one end connecting valve diode D1 of fixed resister R1, the other end is simultaneously
Connect the negative pole end of transient voltage suppressor D2, one end of electric capacity C1 and C2, voltage base
The power input of quasi-N1；The outfan of three end filter Z2, connection transient voltage diode D2
Positive terminal, the other end of capacitor C1 and C2, the power supply negative terminal of voltage reference N1 connect all
It is connected with node SGND.One end of fixed resister R2 is connected with node V+, the other end and joint
Point Vref connects；One end of rheostat R200 is connected with node Vref, the other end and node
SGND connects.The function of voltage reference circuit 1 be by supply voltage through power input VCC and
Current output terminal current output terminal IOUTBy three end filter Z1 and Z2, switching diode D1,
Fixed resister R1, transient voltage suppressor D2, the device such as capacitor C1, C2 and C3
After process, inputing to voltage reference device, voltage reference device is high-precision by node V+ output
Reference voltage, provides work electricity to sensitive electric bridge 2, power amplifier circuit 3 and current converter circuit 4
Pressure, meanwhile, the precision voltage reference utilizing voltage reference circuit 1 to export passes through fixed resister
R2 and adjustable resistor R200 carries out dividing potential drop, to provide adjustable high-accuracy voltage, by joint
Point Vref inputs to voltage amplifier circuit 3, for adjusting the zero-bit output electricity of voltage amplifier circuit 3
Pressure.
Wheatstone presser sensor electric bridge 2 is the four quick electric bridges of arm strength, has tetra-nodes of a, b, c, d,
Node a is the output plus terminal of electric bridge, and node b is the power positive end of electric bridge, and node c is electric bridge
Output negative terminal, node d is the power supply negative terminal of electric bridge.Node b and the node of voltage reference circuit 1
V+ connects, and node d is connected with voltage reference circuit 2 node SGND.Wheatstone presser sensor electricity
Bridge 2 for the pressure signal that pressure transducer inputs is converted into the signal of telecommunication, by node a and
Node c output differential voltage signal.
Voltage amplifier circuit 3 is the three amplifier magnifiers improved, and voltage amplifier circuit 3 wraps
Include operational amplifier N2A, N2B and N2C, fixed resister R3, R4, R5, R6, R7
And R8, capacitor C4, C5 and C6, rheostat R100.Node+Vin and wheatstone pressure
The node a of power sensitivity electric bridge 2 connects, node-Vin and the node c of wheatstone presser sensor electric bridge 2
Connect；The positive input terminal of operational amplifier N2A is connected with node+Vin, operational amplifier N2A
Input be connected with one end of fixed resister R4 and capacitor C4, operational amplifier N2A's
Outfan is connected with the other end of fixed resister R4 and capacitor C4.Operational amplifier N2B's
Positive input terminal is connected with node-Vin, and the input of operational amplifier N2B is simultaneously and fixed resister
One end of R3 and capacitor C5 connects, and the outfan of operational amplifier N2B is simultaneously and fixed resistance
The other end of device R3 and capacitor C5 connects.One end of rheostat R100 and operation amplifier
The negative input end of device N2A connects, the other end of rheostat R100 and operational amplifier N2B
Negative input end connect.One end of resistor R5 is connected with the outfan of operational amplifier N2A,
The other end of resistor R5 is connected with the negative input end of operational amplifier N2C.The one of resistor R6
End is connected with the node Vref of voltage reference circuit 1, the other end of resistor R6 and operation amplifier
The positive input terminal of device N2C connects.One end of resistor R7 and the outfan of operational amplifier N2B
Connecting, the other end of resistor R7 is connected with the positive input terminal of operational amplifier N2C.Computing is put
The negative input end of big device N2C one end with resistor R8 and capacitor C6 respectively is connected, and computing is put
The outfan of the big device N2C other end with resistor R8 and capacitor C6 respectively is connected.Node
Vout is connected with the outfan of operational amplifier N2C.Operational amplifier N2A, N2B, N2C's
Power positive end is connected with node V+, the power supply negative terminal of operational amplifier N2A, N2B, N2C and joint
Point SGND connects.Voltage amplifier circuit 3 is to realize exporting sensitivity electric bridge 2 by above-mentioned device
Difference voltage signal be amplified after, by node Vout input to electric current conversion 4, pass through R200
Realize the adjustment to amplification.In voltage amplifier circuit 3, C4, C5 are connected in parallel on operation amplifier respectively
On device N2A, N2B degeneration resistors R3, R4, Main Function is when presser sensor electric bridge 2
When the difference voltage signal of output is less, eliminate the noise during voltage amplification and interference signal.
Current converter circuit 4 is the Howland current pump circuit improved, including operational amplifier N2D,
Fixed resister R9, R10, R11, R12, R13 and R14, capacitor C7 and C8, three poles
Pipe D3.One end of fixed resister R9 is connected with the node Vout of voltage amplifier circuit 3, fixing
The other end of resistor R9 is connected with the positive input terminal of operational amplifier N2D, and and fixed resistance
One end of R12 connects.One end of fixed resister R10 is connected with node SGND；Fixed resistance
The other end of device R10 is connected with the negative input end of operational amplifier N2D.Fixed resister R11's
One end is connected with one end of capacitor C11, and is connected to the negative input end of operational amplifier N2D
Together；The other end of fixed resister R11 is connected with the other end of capacitor C11, and with fixing
One end of resistor R13, one end of capacitor C8, the emitter stage of audion D3 link together.
The other end of fixed resister R13 and node SGND, and with the other end of fixed resistance R12 even
Connect；The other end of capacitor C8 is connected with the base stage of audion D3, and with operational amplifier N2D
Outfan link together；One end of fixed resister R14 connects with the colelctor electrode of audion D3
Connecing, the other end of fixed resister R14 is connected with node V+.The power supply of operational amplifier N2D
Anode is connected with node V+, and the power supply negative terminal of operational amplifier N2D is connected with node SGND；
Current converter circuit 4 is to realize amplifying amplifying circuit 3 output voltage further, and is converted into ratio
The current signal output of example.
The adjustment method of pressure sensor circuit of the present invention, in conjunction with Fig. 2 pressure transducer adjustment method
Flow chart, is described in detail as follows specific implementation process:
Step 1:
Low-power consumption accurate device operational amplifier and voltage reference is selected, to ensure according to Fig. 1 circuit
The static electric current that consumes of pressure sensor circuit, less than 3.8mA, meets two-wire system 4mA～20mA electricity
The condition of stream output；
The alternative condition of operational amplifier is: the low static electric current that consumes: described operational amplifier N2A,
The maximum static electric current summation that consumes of N2B, N2C and N2D four-operational amplifier is I1；Allow
Single supply, normally works under low-voltage initial conditions；Output voltage amplitude is as close possible to work electricity
Source voltage, track to track operational amplifier is especially suitable；
The alternative condition of voltage reference is: low static consumption electric current, if voltage reference is maximum static
Consumption electric current is I2；Output voltage amplitude can be programmed by output pin or adjustable；Output electricity
Pressing element has high-precision feature；
Step 2:
In the case of sensitive electric bridge difference energising, in maximum operating range, measure sensitive electric bridge
Minimum internal resistance value R(B), as the foundation determining that voltage reference output voltage amplitude calculates；
Step 3:
The computational methods of the output voltage amplitude span of voltage reference are: Uo ＜ 3.8-I1-I2?
×RB；
Step 4:
In order to ensure that the static electric current that consumes of pressure sensor circuit is not more than 3.8mA with satisfied described
Pressure sensor circuit has the condition of adjustable.Then have and determine checking for zero benchmark fixed resister
The span of R2 resistance value is: R2 >=3.8-I1-I2-Uo/RB?.
By step 1,2,3,4 main devices determined respectively, the output voltage amplitude of pressure benchmark
Span, the span of checking for zero benchmark fixed resister R2 resistance value, it is ensured that pressure
The static electric current that consumes of sensor circuit, less than 3.8mA, meets the commissioning requirements of pressure transducer.
Step 5:
The resistance value of main fixed resister in preset current change-over circuit 4, should meet following condition:
R9=R10, R11=R12, R11, the resistance value of R12 are much larger than R13, should meet R13≤0.1%
× R11, and R13 >=100 Ω.
It is the most accurate that R9 and R10, the coupling of R11 and R12 make voltage signal amplify, R13≤0.1%
× R11, it is therefore an objective to improve the output impedance of current converter circuit 4.
Step 6:
The resistance value of the above-mentioned preset each fixed resister according to current converter circuit 4, calculates pressure
During force transducer Full-span output, the magnitude of voltage calculating formula of voltage amplifier circuit 3 output end vo ut is:
Uout=(IOMAX×R13)×R9/R12.Wherein IOMAXMaximum output electricity for pressure transducer
Stream amplitude.
Step 7:
According to the output sensitivity of presser sensor electric bridge, determine the amplification of voltage amplifier circuit 3.
If the output voltage sensitivity of presser sensor electric bridge is Vs, then the amplification of voltage amplifier circuit 3
A=Uout/ (Vs × Uo).Amplification A of voltage amplifier circuit 3 should be not more than 150.
If being unsatisfactory for above-mentioned requirements, then should again change in current converter circuit 4 according to step 5
The resistance value that fixed resister is preset, suitably reduces the resistance of R9 during concrete amplification.
Step 8:
Maximum input offset current I according to operational amplifierBWith maximum input bias current IOS, with
And the minimum zero-bit output voltage U of sensitivity electric bridgeBMIN, determine that amplification adjusts resistance R100's
Maximum occurrences.Computational methods are as follows: R100≤UBMIN/(IB+IOS)。
Step 9:
Amplification A and amplification according to voltage amplifier circuit 3 adjust resistance R100, calculate
The resistance value span of fixed resister R3, R4, computational methods are: R3=R4≤R100 ×
(A-1)/2。
Control the Standard resistance range of R100 by step 8, step 9 controls the value model of R3 and R4
Enclose, make operational amplifier be operated in optimum state, reduce owing to the input of operational amplifier is lacked of proper care electric
The impact that small-signal is amplified by stream and bias current, improves the stability amplifying voltage.
Step 10:
The resistance value of remaining fixed resister in selected voltage amplifier circuit 3.Should meet following condition:
R5=R6=R7=R8 >=10k Ω.
Step 11:
When debugging, the output of presser sensor electric bridge being maintained at zero-bit output, keeping R100 is
Big value is constant, adjusts the resistance of R200, and the output current value making pressure sensor circuit is 4mA,
Observe the saltus step situation of current value.In above-mentioned condition, from ceramic capacitor C3=C4=0.01uF gradually
Increase the capacitance of C3, C4, until after output is stable, then the capacitance of C3, C4 is increased
50%, as the final value of C3, C4 capacitance, to ensure that amplifying circuit 3 is operated in stable shape
State, it is to avoid the fluctuation of output voltage and affect the output of pressure transducer.
Step 12:
Electro Magnetic Compatibilities according to pressure transducer etc. require to determine the parameter of other components and parts in circuit,
Specification and parameter such as devices such as Z1, Z2, D1, D2, C1, C2, R1, R14.
Step 13:
By adjusting rheostat R100 and R200, the zero-bit of pressure transducer is made to be output as 4mA,
20mA it is output as during maximum pressure.
Embodiment
As in figure 2 it is shown, sensitive electric bridge 2 selects sputtered film presser sensor electric bridge, its output is sensitive
Degree is 1.5mV, and the bridge resistance minima of sensitive electric bridge is 3.2k Ω, and minimum zero-bit output voltage is
0.1mV, implements step as follows:
Step 1, selection low-power consumption accurate device operational amplifier and voltage reference:
Main low-power consumption accurate device operational amplifier and voltage reference is selected according to Fig. 1 circuit.
The alternative condition of operational amplifier is: the low static electric current that consumes: described operational amplifier N2A,
The maximum static electric current summation that consumes of N2B, N2C and N2D four-operational amplifier is I1, then should have
I1≤1.5mA；Allow normally to work under single supply, low-voltage initial conditions；Output voltage amplitude
As close possible to working power voltage, track to track operational amplifier is especially suitable.As selected track to track
The low-power consumption four-way operational amplifiers such as four-way operational amplifier OP491 or ADA4091-4,
Commissioning requirements can be met.
The alternative condition of voltage reference is: low static consumption electric current, if voltage reference is maximum static
Consumption electric current is I2, then should have I2≤1.2mA；Output voltage amplitude can be programmed by output pin or
Person's adjustable；Output voltage has high-precision feature.Such as high-precision voltage reference AD584 able to programme.
The minimum internal resistance value of the sensitive electric bridge of step 2, mensuration:
In the case of sensitive electric bridge difference energising, in maximum operating range, measure sensitive electric bridge
Minimum internal resistance value RB。
The sputtered film presser sensor electric bridge selected, the minimum internal resistance value R in operating temperature range(B)
=3.2k Ω.
Step 3, determine the output voltage amplitude of voltage reference:
The output voltage amplitude of voltage reference is determined: Uo ＜ 3.8-I by calculating formula1-I2× RB。
The track to track four-way operational amplifier OP491 that step 1 selects, its maximum static consumption electricity
Stream I1≤1.2mA；High-precision voltage reference AD584 able to programme, its maximum static consumption electric current I2
≤1.0mA.And the minimum internal resistance value R of sensitivity electric bridge(B)=3.2k Ω, then have Uo ＜ 3.8-I1-I2?
×R(B)=5.12V.
The output voltage of high-precision voltage reference AD584 able to programme is chosen as Uo=5V.
Step 4, determine the resistance value of checking for zero benchmark fixed resister R2:
Determine the resistance value of checking for zero benchmark fixed resister R2.In order to ensure pressure transducer electricity
The static electric current no more than 3.8mA that consumes on road has adjustable to meet described pressure sensor circuit
Condition.Then have: R2 >=3.8-I1-I2-Uo/RB?.
According to above-mentioned confirmable parameter, it may be determined that R2 >=133k Ω, desirable R2=200k Ω.
The resistance value of main fixed resister in step 5, preset current change-over circuit 4；
The resistance value of main fixed resister in preset current change-over circuit 4, should meet following condition:
R9=R10, R11=R12, R11, the resistance value of R12 are much larger than R13, typically should meet R13
≤ 0.1% × R11, and R13 >=100 Ω.
According to the resistance value of fixed resister main in above-mentioned condition preset current change-over circuit 4, as
Take R9=R10=47k Ω, R11=R12=200k Ω, R13=150 Ω.
Step 6, the magnitude of voltage of calculating voltage amplifier circuit (3) output end vo ut:
The resistance value of the above-mentioned preset each fixed resister according to current converter circuit 4, calculates pressure
During force transducer Full-span output, the magnitude of voltage calculating formula of voltage amplifier circuit (3) output end vo ut
For: Uout=(I(OMAX)×R13)×R9/R12.Wherein I(OMAX)For pressure transducer
Export greatly current amplitude, I(OMAX)=(20-4) mA=16mA.
Then Uout=(I(OMAX)× R13) × R9/R12=564mV.
Step 7, determine the amplification of voltage amplifier circuit 3:
According to the output sensitivity of presser sensor electric bridge, determine the amplification of voltage amplifier circuit 3.
If the output voltage sensitivity of presser sensor electric bridge is Vs, then the amplification of voltage amplifier circuit 3
A=Uout/ (Vs × Uo).Amplification A of voltage amplifier circuit 3 should be not more than 150.
If being unsatisfactory for above-mentioned requirements, then should again change in current converter circuit 4 according to step 5
The resistance value that fixed resister is preset, suitably reduces the resistance of R9 during concrete amplification.
The sputtered film presser sensor electric bridge of above-mentioned employing, the sensitivity of output voltage is 1.5mV/V,
Amplification A=Uout/ (Vs × Uo)=75.2 of voltage amplifier circuit 3 then can be calculated according to above formula
＜ 150, meets design requirement.
Step 8, determine amplification adjust resistance R100 maximum occurrences:
Maximum input offset current I according to operational amplifierBWith maximum input bias current IOS, with
And the minimum zero-bit output voltage U of sensitivity electric bridge(BMIN), determine that amplification adjusts resistance R100
Maximum occurrences scope.Computational methods are as follows: R100≤UBMIN/(IB+IOS)。
Inquiry OP491 tables of data understands: the maximum input offset current I of operational amplifierB=95nA,
Maximum input bias current IOS=22nA.The sputtered film presser sensor electric bridge measuring above-mentioned employing exists
Under the conditions of running voltage Uo, minimum output voltage UBMIN=0.1mV.
Amplification adjusts resistance R100≤U(BMIN)/(IB+IOS)=854.7 Ω.
Step 9, determine the span of fixed resister R3, R4:
Amplification A and amplification according to voltage amplifier circuit 3 adjust resistance R100, calculate
The resistance value of fixed resister R3, R4, computational methods are: R3=R4≤R100 × (A-1)/2.
The parameter determined according to abovementioned steps: A=75.2, R100≤854.7 Ω, calculates: R3=R4=
≤ R100 × (A-1)/2=31.709k Ω.
According to above-mentioned value of calculation, it is considered to the stability margin of holding circuit, take R3=R4=15k Ω.
The resistance value of remaining fixed resister in step 10, selected voltage amplifier circuit 3:
The resistance value of remaining fixed resister in selected voltage amplifier circuit 3, should meet following condition:
R5=R6=R7=R8 >=10k Ω.
Select R5=R6=R7=R8=200k Ω.
Step 11, determine the capacitance of capacitor C3, C4:
When debugging, the output of presser sensor electric bridge being maintained at zero-bit output, keeping R100 is
Big value is constant, adjusts the resistance of R200, and the output current value making pressure sensor circuit is 4mA,
Observe the saltus step situation of current value.In above-mentioned condition, from ceramic capacitor C3=C4=0.01uF gradually
Increase the capacitance of C3, C4, until after output is stable, then the capacitance of C3, C4 is increased
50%.
According to said method, as C3=C4=0.47uF, zero current output is stable；The most final
Choose C3=C4=1uF.
Step 12, determines the parameter of other components and parts in circuit:
Electro Magnetic Compatibility according to pressure transducer etc. itself it is determined that the parameter of other components and parts in circuit,
Specification and parameter such as devices such as Z1, Z2, D1, D2, C1, C2, R1, R14.
Step 13, adjustment rheostat R100 and R200:
By adjusting rheostat R100 and R200, the zero-bit of pressure transducer is made to be output as 4mA,
20mA it is output as during maximum pressure.
By checking, the pressure transducer designed according to foregoing circuit structure and adjustment method, have
Good stability, in (-40～70) DEG C temperature range, synthetic error is respectively less than ± 1%.
Claims (10)
1. a pressure sensor circuit, it is characterised in that: include voltage reference circuit (1), quick
Inductance bridge (2), voltage amplifier circuit (3), current converter circuit (4) four part, wherein, pressure
Force transducer includes electrical node VCC, IOUT、SGND、V+、Vref、Earth、+Vin、-Vin
And Vout；Voltage reference circuit (1) and node VCC, IOUT, SGND, V+, Vref and
Earth is connected, and sensitive electric bridge (2) is by node SGND, V+ and voltage reference circuit (1)
Connecting, sensitive electric bridge (2) is connected with voltage amplifier circuit (3) by node+Vin ,-Vin,
Voltage amplifier circuit (3) is by node V+, SGND, Vref with voltage reference circuit (1) even
Connecing, voltage amplifier circuit (3) is connected with current converter circuit (4) by node Vout, electric current
Change-over circuit (4) is connected with voltage reference circuit (1) by node V+, SGND, wherein,
Described electrical node VCC, IOUT、SGND、V+、Vref、Earth、+Vin、-Vin、Vout
Electrical Location be respectively the power input of pressure transducer, the current output terminal of pressure transducer,
Signal ground, the outfan of voltage reference circuit, zero-bit debugging voltage output end, shielding ground, voltage
The positive input terminal of amplifying circuit (3), the negative input end of voltage amplifier circuit (3), voltage amplification
The outfan of circuit (3).
Pressure sensor circuit the most according to claim 1, it is characterised in that described computing
Amplifier N2A, N2B, N2C and N2D are low consumed power operational amplifier, voltage reference circuit (1)
Select the voltage reference device of low-power consumption.
Pressure sensor circuit the most according to claim 2, it is characterised in that voltage reference
The output voltage amplitude of circuit (1) determines by the following method: Uo ＜ 3.8-I1-I2× RB,
Wherein Uo is the output voltage of voltage reference, RBFor the minimum internal resistance value of sensitive electric bridge (2), I1
Maximum static for four-way operational amplifier consumes electric current, I2Disappear for setting the maximum static state of voltage reference
Power consumption stream.
Pressure sensor circuit the most according to claim 2, it is characterised in that described fixing
Resistor R2, R3, R4 ... R13, R14 select the resistance device of low inductance, wherein resistance
Value R3=R4≤50k Ω, R5=R6=R7=R8 >=10k Ω, R9=R10, R11=R12, meet
R13≤0.1% × R11, and R13 >=100 Ω.
Pressure sensor circuit the most according to claim 4, it is characterised in that determine zero-bit
The computational methods adjusting benchmark fixed resister R2 resistance value scope are: R2 >=
3.8-I1-I2-Uo/RB?.
Pressure sensor circuit the most according to claim 5, it is characterised in that according to electric current
The resistance value of each fixed resister preset in change-over circuit (4), calculates voltage amplifier circuit (3)
The magnitude of voltage Uout of output end vo ut, computational methods are: Uout=(IOMAX× R13) × R9/R12,
Wherein I(OMAX)Maximum output current amplitude for pressure transducer.
Pressure sensor circuit the most according to claim 6, it is characterised in that voltage amplification
Amplification A=Uout/ (Vs × Uo) of circuit (3), wherein the output electricity of presser sensor electric bridge
Pressure sensitivity is Vs, and amplification A of voltage amplifier circuit (3) should be not more than 150；If it is electric
Amplification A of pressure amplifying circuit (3) is unsatisfactory for requirement, then should again change current converter circuit
(4) resistance value that in, fixed resister is preset, method particularly includes: keep R11, R12, R13
Resistance value constant, synchronize reduce R9, R10 resistance value, until making voltage amplifier circuit (3)
Amplification A≤150.
Pressure sensor circuit the most according to claim 7, it is characterised in that according to computing
The maximum input offset current I of amplifierBWith maximum input bias current IOS, and sensitive electric bridge
Minimum zero-bit output voltage UBMIN, determine that amplification adjusts the maximum occurrences scope of resistance R100,
Computational methods are as follows: R100≤UBMIN/(IB+IOS)。
Pressure sensor circuit the most according to claim 8, it is characterised in that: when debugging,
The output of presser sensor electric bridge is maintained at zero-bit output, and keeping R100 is that maximum is constant, adjusts
The resistance of R200, the output current value making pressure sensor circuit is 4mA, observes the jumping of current value
Change situation, in above-mentioned condition, is gradually increased C3, C4 from ceramic capacitor C3=C4=0.01uF
Capacitance, until after output is stable, then increases 50% by the capacitance of C3, C4, as C3,
The final value of C4 capacitance.
10. an adjustment method based on the pressure transducer described in claim 1, it is characterised in that tool
Body process is as follows: in step 1, selection voltage reference circuit (1), low-power consumption accurate device computing is put
Big device and voltage reference, step 2, measure the minimum internal resistance value of sensitive electric bridge (2), step 3, determines
The output voltage amplitude of voltage reference in voltage reference circuit 1, step 4, determines voltage reference circuit
(1) resistance value of checking for zero benchmark fixed resister in, by step 1, step 2, step 3,
Main devices that step 4 determines respectively, the output voltage amplitude span of pressure benchmark, checking for zero
The span of benchmark fixed resister R2 resistance value, it is ensured that the static consumption of pressure sensor circuit
Electric current is less than 3.8mA, meets the commissioning requirements of pressure transducer；Step 5, preset current conversion electricity
The resistance value of fixed resister in road (4), makes voltage signal amplify the most accurate, improves electric current and turns
Change the output impedance of circuit (4)；Step 6, calculate voltage amplifier circuit (3) output end vo ut
Magnitude of voltage, step 7, determines the amplification of voltage amplifier circuit 3, step 8, determines voltage amplification
In circuit (3), amplification adjusts the maximum occurrences of resistor, step 9, selected voltage amplification electricity
In road 3, the resistance value for the negative feedback fixed resister of two operational amplifiers of differential amplification takes
Value scope, by step 6,7,8,9 realizes in voltage amplifier circuit (3) amplification and adjusts electricity
The maximum occurrences of resistance device, the negative feedback fixed resister of two operational amplifiers for differential amplification
Resistance value span, make operational amplifier be operated in optimum state, reduce due to operation amplifier
The impact that small-signal is amplified by the input offset current of device and bias current, improves and amplifies voltage
Stability；The resistance value of remaining fixed resister in step 10, selected voltage amplifier circuit (3)；
Step 11, determine two operational amplifiers negative for differential amplification in voltage amplifier circuit (3)
The capacitance of feedback condenser, to ensure that amplifying circuit (3) is operated in steady statue, it is to avoid output
The fluctuation of voltage and affect the output of pressure transducer；Step 12, determine other components and parts in circuit
Parameter；Checking for zero rheostat and voltage in step 13, adjustment voltage reference circuit (1)
In amplifying circuit (3), amplification adjusts the resistance value of resistor, and the zero-bit making pressure transducer is defeated
Go out and meet requirement with output valve during maximum pressure.
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| CN108151771A (en) * | 2017-12-20 | 2018-06-12 | 哈尔滨广瀚燃气轮机有限公司 | A kind of gas turbine throttle position transmitter |
| CN108692837A (en) * | 2017-04-06 | 2018-10-23 | 恩智浦美国有限公司 | Signal interface circuit and pressure sensor systems including signal interface circuit |
| CN108871633A (en) * | 2017-05-10 | 2018-11-23 | 盾安传感科技有限公司 | The signal conditioning circuit of pressure sensor |
| CN112014004A (en) * | 2019-05-29 | 2020-12-01 | 硅微结构股份有限公司 | Voltage zero setting pressure sensor preamplifier |
| CN112179528A (en) * | 2020-08-21 | 2021-01-05 | 武汉中航传感技术有限责任公司 | CMOS integrated circuit and pressure sensor |
| CN112379246A (en) * | 2020-11-17 | 2021-02-19 | 西安卓越智动科技有限公司 | Thin film type pressure sensor interface circuit debugging method based on wearable equipment |
| CN113984251A (en) * | 2021-10-26 | 2022-01-28 | 西安微电子技术研究所 | Debugging method of silicon piezoresistive pressure sensor |
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| CN108692837A (en) * | 2017-04-06 | 2018-10-23 | 恩智浦美国有限公司 | Signal interface circuit and pressure sensor systems including signal interface circuit |
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| CN112014004A (en) * | 2019-05-29 | 2020-12-01 | 硅微结构股份有限公司 | Voltage zero setting pressure sensor preamplifier |
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| CN112379246A (en) * | 2020-11-17 | 2021-02-19 | 西安卓越智动科技有限公司 | Thin film type pressure sensor interface circuit debugging method based on wearable equipment |
| CN113984251A (en) * | 2021-10-26 | 2022-01-28 | 西安微电子技术研究所 | Debugging method of silicon piezoresistive pressure sensor |
| CN113984251B (en) * | 2021-10-26 | 2023-09-22 | 西安微电子技术研究所 | Debugging method of silicon piezoresistive pressure sensor |
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