CN2676210Y - Driver and signal collector for resonant transducer - Google Patents

Abstract

The utility model relates to a driver and signal collector for the resonant transducer which can measure the electronic device of the impedance spectrum in real time and is particularly used for driving and measuring for the resonant transducer. The whole driver and signal collector circuit comprises a sine signal generating circuit 1 comprising DDS, AGC, and Amp1, a transducer driving circuit 2 comprising an operational amplifier, a transducer (such as QCM), and a referential resistor, an analog signal collecting and processing circuit 3 comprising an analog multiplier and a low pass filter and level conversion operational amplifier, and a digit signal collecting processing and control circuit 4 comprising a multi-way switch, an analogue-to-digital converter, and a central processing unit. A sine signal is acted on two inverter ratio circuits to drive the QCM to vibrate; the amplitude value and the phase angle of the equivalent impedance of the QCM can be achieved through the output signal of each inverter ratio circuits. The voltage acting on the QCM remains constant, and the circuit structure and the subsequent calculation are simplified; the speed is improved, and the driver and signal collector for the resonant transducer which can measure the electronic device has two work patterns.

Description

The driving of resonant transducer and signal picker

Technical field

The utility model relates to a kind of electron device that can measure impedance spectrum in real time, in particular for the driving and the measurement of resonant transducer.It designs at crystal microbalance (QCM), but also can be used for the resonant transducer of other type.

Background technology

Crystal microbalance is to plate a kind of resonant transducer that circular gold electrode constitutes in the upper and lower surface that circular AT cuts piezoid.It has simple in structure, and cost is low, and is highly sensitive, but real-time online detect, advantage such as vibration loss is little in liquid phase, very extensive in field application prospects such as biology, chemistry, environmental protection, food.

At present, the method that drives the QCM vibration and gather its output signal mainly contains two kinds: the method for (1) oscillatory circuit; (2) method of spectrum analysis.The ultimate principle of oscillatory circuit method is: QCM is inserted in the self-maintained circuit, make it constitute the frequency-selecting element, the oscillation frequency of circuit equals the resonance frequency of QCM.Variation by the circuit oscillation frequency can obtain the QCM change of resonance frequency, thereby can infer the variation of test substance character.The ultimate principle of frequency spectrum analysis method is: near scanning QCM frequency spectrum in the band frequency scope (amplitude-frequency of QCM equiva lent impedance and phase-frequency characteristic) its resonance frequency can obtain the many parameters of resonance frequency, Q value or the like of QCM by this frequency spectrum.Compare with the method for oscillatory circuit, the major advantage of spectrum analysis has: can failure of oscillation in big resisting medium, and measurement result contains much information, and is visual in image, calculates and explains easily.When QCM vibrated in liquid, the output signal of QCM can be subjected to influence of various factors in addition, as: the surfaceness of the viscosity of liquid, density, conductivity, electrode and water wettability etc.Output by spectrum analysis can be distinguished these phenomenons effectively.Though have recently the researchist to propose to measure simultaneously that resonance frequency changes and the variation of Q value (or bandwidth, equivalent resistance, dissipation) improves the method for oscillatory circuit performance with oscillatory circuit, frequency spectrum analysis method is still irreplaceable owing to above-mentioned peculiar advantage.

Yet the required spectrum analyzer of frequency spectrum analysis method is bulky, costs an arm and a leg, and be unsuitable for the application in the actual production, and its real-time is relatively poor, can not bring into play the advantage that QCM measures in real time.

J.Schr der etc. has proposed a kind of way (Advancedinterface electronics and methods for QCM that realizes spectrum analysis with monolithic integrated circuit in paper, Sensors and Actuators is (2002) 543-547 A.97-98, J.Schr der et.al).Its ultimate principle is (referring to Fig. 1): (frequency that the DDS chip produces is f for Logic Cell Array, LCA) synthetic (DDS) chip of control Direct Digital signal by logical cell array ₀Sinusoidal signal after low-pass filtering, drive the series circuit of forming by resistance R s and QCM, by measuring amplitude and the phase angle that dividing potential drop Vq on total driving voltage Vg and the QCM then can obtain the QCM equiva lent impedance.The total driving voltage and the dividing potential drop on the QCM of taking out are f with the frequency that another DDS sends respectively ₀The signal mixing of+10K, and after low-pass filtering, remain two signals that frequency is 10K.Can obtain the phase differential of these two low frequency signals by phase difference detecting circuit, the core of phase difference detecting circuit is a high-speed comparator.This two-way low frequency signal is sent to rectification, filtering circuit more simultaneously.The phase differential of the amplitude by the two-way direct current signal that obtains after the filtering and two low frequency signals that obtain previously can calculate the amplitude and the phase angle of QCM equiva lent impedance.The signal frequency f that LCA can produce by the control word control DDS of DDS ₀, constantly change f ₀Can obtain the amplitude and the phase angle of QCM equiva lent impedance under the different frequency, be the amplitude-frequency and the phase-frequency characteristic of QCM equiva lent impedance.

Though the frequency spectrum that QCM driving that J.Schr der etc. is proposed and signal picker can record QCM with monolithic integrated circuit also exists following shortcoming:

(1), the own structure more complicated of circuit.Remove outside the essential parts such as analog switch, modulus conversion chip ADC and control circuit, it comprises each two of DDS chips, frequency mixer, precise rectification circuit altogether, also has the different low-pass filter of six cutoff frequencys and the phase difference detecting circuit of a special use.The components and parts of circuit are more.

(2), the required calculation of complex of digital signal.Circuit obtains three digital signals altogether, is respectively: two digital signals relevant with the two paths of signals amplitude from ADC output, a digital signal that is obtained by phase detecting circuit.Because the equiva lent impedance of QCM is a plural number, so can not directly obtain the amplitude of equiva lent impedance by two digital signals from ADC output; And be not the phase angle of equiva lent impedance from the phase differential that phase detecting circuit obtains yet.Obtain the amplitude and the phase angle of QCM equiva lent impedance, must carry out the complex mathematical computing by these three digital signals and obtain.

(3), the speed of circuit also needs further to improve.

Summary of the invention

The utility model proposes driving and signal picker that another can measure the resonant transducer of QCM equiva lent impedance frequency spectrum, can address the above problem.

Technical solution of the present utility model is as follows: whole driving and signal picker circuit comprise that sinusoidal signal produces circuit 1, sensor drive driving circuit 2, collection of simulant signal and treatment circuit 3, digital signal acquiring is handled and control circuit 4 four parts.Wherein, sinusoidal signal produces circuit and is made up of Direct Digital signal synthesis chip DDS, automatic gaining controling chip AGC and level and impedance transformation operational amplifier A mp1; Sensor drive driving circuit is made up of operational amplifier A mp2 and Amp3, sensor (for example QCM), reference resistance R1 and R2 and R3; Collection of simulant signal and treatment circuit are made up of analog multiplier MLPR1 and MLPR2, low-pass filter LPF1 and LPF2 and level conversion operational amplifier A mp4 and Amp5; Digital signal acquiring is handled and control circuit is made up of multi-way switch MUX, analog to digital converter ADC and central processor CPU.The input end of DDS links to each other with the control port of CPU; DDS, AGC link to each other in proper order with Amp1 then; The output terminal of Amp1 links to each other with the input end of sensor, the input end of R2 simultaneously; The output terminal of sensor and R2 links to each other with the inverting input of Amp2, Amp3 respectively; The in-phase end of Amp2, Amp3 is ground connection simultaneously, and reference resistance R2 and R3 then are connected across respectively between the output terminal and inverting input of operational amplifier A mp2 and Amp3; The output terminal of Amp2, Amp3 links to each other with the X input end with the Y input end of multiplier MLPR2 respectively; The output terminal of Amp2 then also links to each other with the Y input end with the X input end of multiplier MLPR1 simultaneously; The output terminal of two analog multiplier MLPR1 and MLPR2 links to each other with Amp5 with Amp4, LPF2 in proper order with LPF1 respectively; The output terminal of Amp4, Amp5 links to each other with two different input ends of multi-way switch MUX respectively, and the input end of analog signal of two corresponding output termination analog to digital converter ADC of multi-way switch; The numerical data output port of ADC links to each other with the numerical data input port of central processor CPU; The control port of CPU also links to each other with the channel selecting port of multi-way switch MUX and the control input end of ADC respectively.

The course of work of the present utility model is as follows: send steering order by central processor CPU to the DDS chip, make it produce sinusoidal signal.The output signal of DDS is imported two anti-phase ratio circuits that are barricaded as by operational amplifier A mp2, Amp3 and corresponding reference resistance behind AGC and Amp1.Two analog multiplier MLPR1 are sent in the output of these two anti-phase ratio circuits and MLPR2 carries out analog signal processing.The output signal of two analog multipliers is sent into ADC by multi-way switch respectively after low-pass filtering, voltage amplification.ADC accepts the control of control CPU, and the result of ADC conversion is sent into CPU.CPU carries out calculation process with the digital signal of ADC input at last, can also send into the usefulness of PC demonstration for further analysis through the PC interface.

Sinusoidal signal produces circuit and is made up of the synthetic DDS of Direct Digital signal, automatic gain control AGC and amplifier Amp1.DDS accepts the control of CPU, produces the controlled sinusoidal signal of frequency; The signal that AGC adjusts DDS output makes the amplitude of its output signal remain a predetermined value; Amp1 then finishes the level and the impedance transformation of signal.Make the voltage magnitude of its generation keep constant because the signal generator branch has increased automatic gain control AGC, and reduced the number of measured signal.

Different with the circuit that J.Schr der etc. proposes, the signal that sinusoidal signal produces circuit output is not to act on the series circuit of QCM and resistance, again amplitude and the phase angle that obtains the QCM equiva lent impedance by total voltage on the measurement series circuit and the dividing potential drop on the QCM; But sinusoidal signal is acted on as shown in the figure two anti-phase ratio circuits, drive the QCM vibration.Can obtain the amplitude and the phase angle of QCM equiva lent impedance by the output signal of two anti-phase ratio circuits.According to the principle of anti-phase ratio circuit virtual earth, the voltage that acts on the QCM remains the output voltage of signal generator branch and the voltage difference between the ground.Adopt the benefit of this structure to be:

(1), the voltage magnitude that acts on the QCM keeps constant.

(2), make follow-up calculating simple.

(3), (calculating by the back will obtain this conclusion only can to obtain the amplitude of QCM equiva lent impedance separately by the output signal of an anti-phase ratio circuit.)

The core of collection of simulant signal and processing section is two analog multipliers and two low-pass filters.If the output voltage of signal generating circuit is: u=u ⁰Cos (ω t).The anti-phase ratio circuit that then contains QCM is output as:

$u_1=-u^0\frac{{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="Y20032012423000091.png,Y20032012423000092.png"\; state="\{\{state\}\}">R</figure-callout>}}_1}{\left|Z\right|}\cos (\mathrm{\&omega;}t-\mathrm{\&phi;})$

In the formula: R ₁Be reference resistance R ₁Resistance, | Z| and φ are respectively the amplitude and the phase angle of the equiva lent impedance of QCM.Another anti-phase ratio circuit is output as:

$u_2=-u^0\frac{R_3}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="Y20032012423000101.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}\cos \mathrm{\&omega;t}$

In the formula: R ₂, R ₃Be respectively reference resistance R ₂And R ₃Resistance.

This two paths of signals is admitted to two analog multipliers.

Multiplier 1 makes the AC signal involution of the anti-phase ratio circuit output that comprises QCM in the QCM drive part, and it is output as:

${\mathrm{<figure-callout\; id="1"\; label="u\; m"\; filenames="Y20032012423000091.png,Y20032012423000092.png"\; state="\{\{state\}\}">u</figure-callout>}}_m={[-u^0\frac{{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="Y20032012423000091.png,Y20032012423000092.png"\; state="\{\{state\}\}">R</figure-callout>}}_1}{\left|Z\right|}\cos (\mathrm{\&omega;t}-\mathrm{\&phi;})]}^2=\frac{1}{2}{\left(\frac{u^0{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="Y20032012423000091.png,Y20032012423000092.png"\; state="\{\{state\}\}">R</figure-callout>}}_1}{\left|Z\right|}\right)}^2[1+\cos (2\mathrm{\&omega;t}-2\mathrm{\&phi;})];$

The AC signal that multiplier 2 will comprise anti-phase ratio circuit AC signal of exporting and the anti-phase ratio circuit output that does not comprise QCM of QCM multiplies each other, and it is output as:

${\mathrm{<figure-callout\; id="2"\; label="u\; m"\; filenames="Y20032012423000101.png"\; state="\{\{state\}\}">u</figure-callout>}}_m={\left(u^0\right)}^2\frac{R_1{R}_3}{R_2\left|Z\right|}\cos \left(\mathrm{\&omega;t}\right)\cos (\mathrm{\&omega;t}-\mathrm{\&phi;})={\left(u^0\right)}^2\frac{R_1{R}_3}{2R_2\left|Z\right|}[\cos \mathrm{\&phi;}+\cos (2\mathrm{\&omega;t}-\mathrm{\&phi;})];$

The output of two-way output signal behind low-pass filter LPF is respectively: ${\mathrm{<figure-callout\; id="1"\; label="u\; f"\; filenames="Y20032012423000091.png,Y20032012423000092.png"\; state="\{\{state\}\}">u</figure-callout>}}_f=\frac{1}{2}{\left(\frac{u^0{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="Y20032012423000091.png,Y20032012423000092.png"\; state="\{\{state\}\}">R</figure-callout>}}_1}{\left|Z\right|}\right)}^2\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(1\right);$

With: $u_{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="Y20032012423000101.png"\; state="\{\{state\}\}">f</figure-callout>}2}={\left(u^0\right)}^2\frac{R_1{\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="Y20032012423000101.png"\; state="\{\{state\}\}">R</figure-callout>}}_3}{2{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="Y20032012423000101.png"\; state="\{\{state\}\}">R</figure-callout>}}_2\left|Z\right|}\cos \mathrm{\&phi;}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(2\right);$

These two direct current signals are sent to analog to digital converter ADC through voltage transitions and the multi-way switch of amplifier Amp4 and Amp5, and the result of AD conversion is sent to the usefulness of PC for analysis, demonstration again after CPU handles.

Analysis circuit and arrangement are 1., 2. two formulas can get:

The amplitude of QCM equiva lent impedance: $\left|Z\right|=\frac{u^0{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="Y20032012423000091.png,Y20032012423000092.png"\; state="\{\{state\}\}">R</figure-callout>}}_1}{\sqrt{2u_{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="Y20032012423000091.png,Y20032012423000092.png"\; state="\{\{state\}\}">f</figure-callout>}1}}}......\left(3\right)$

The phase angle of QCM equiva lent impedance: $\mathrm{\&phi;}=\mathrm{co}{s}^{-1}\frac{2{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="Y20032012423000101.png"\; state="\{\{state\}\}">R</figure-callout>}}_2\left|Z\right|u_{f2}}{R_1{R}_3{\left(u^0\right)}^2}......\left(4\right)$

Above R in two formulas ₁, R ₂, R ₃And u ⁰Be the given value relevant with circuit parameter.So by the signal u that gathers _F1And u _F2, by 3., 4. two formulas can calculate the amplitude and the phase angle of QCM equiva lent impedance respectively.The frequency of the signal that change to produce by DDS can obtain the amplitude and the phase angle of QCM equiva lent impedance under the different frequency, i.e. the frequency spectrum of QCM.

As seen pass through u by 3. formula _F1Can obtain the amplitude of QCM equiva lent impedance separately, obtain the amplitude-versus-frequency curve of QCM.Therefore this circuit can be set two kinds of mode of operations: 1, make only acquired signal u of circuit _F1Thereby, can obtain the amplitude-versus-frequency curve of QCM, can obtain the parameter such as resonance frequency (impedance magnitude minimum point), bandwidth, Q value of QCM by this curve.Because one road signal is only gathered, handled to this pattern, so pattern 1 operating rate is very fast.2, gather, handle two paths of signals u simultaneously _F1And u _F2Thereby, can obtain amplitude versus frequency characte and the phase-frequency characteristic curve of QCM.Adopt this pattern can obtain the most comprehensive information of QCM, but its operating rate is slow than pattern 1.

Compare with the method for propositions such as J.Schr der, the utility model has the advantages that fairly obvious:

(1), the signal generator that has improved circuit divides and signal acts on the mode that makes its vibration on the QCM.Make the voltage that acts on the QCM keep constant, simplified follow-up required calculating, improved speed, and made circuit have two kinds of mode of operations of speed.

(2), improve and simplified collection of simulant signal and processing section.As think the frequency mixer equivalence that multiplier in this circuit and J.Schr der are adopted, and then having saved three wave filters, two precision rectifers, DDS and phase detecting circuit in this circuit, simplification is fairly obvious.And, can improve speed so reduce filtering circuit because filtering circuit has time-lag action.

Description of drawings

Accompanying drawing 1 is the circuit theory diagrams of prior art.

Accompanying drawing 2 is circuit theory diagrams of the present utility model.

Accompanying drawing 3 is that the physical circuit figure of the utility model embodiment (illustrates: for the sake of clarity, omitted some non-main elements in the drawings, as the decoupling capacitance of power supply, the configuration element of integrated circuit etc.; Because the pin of DSP is a lot, so also do not draw with the incoherent pin of the utility model function.The concrete numerical value of this type of abridged element and pin and connected mode all can find on the databook of respective element).

Embodiment

(Fig. 2,3) makes a detailed explanation the utility model below in conjunction with accompanying drawing: in specific embodiment of the utility model, the fundamental frequency of QCM (Fundamental Frequency) is 5MHz.The DDS chip has used AD9835, and automatic gain control is then built by AD8367.AD8367 is the variable gain amplifier of integrated square-law detector (Square-LawDetector) on the sheet, uses this chip can be barricaded as automatic gain control amplifier AGC easily.Multiplier has then adopted AD835.CPU has adopted dsp chip TMS320F2810, because this dsp chip carries 12 A/D convertor circuits of 16 tunnel, has therefore in fact saved multi-way switch and the analog to digital converter in the schematic diagram in an embodiment.Communication between resonant transducer driving and signal picker and the PC realizes that by parallel port the parallel port mode of operation of selecting for use is the PS/2 pattern.Empirical tests embodiment circuit is when 1 time work of pattern, and the data of gathering a Frequency point need 0.5ms at most, and need 0.8ms at most 2 times in pattern.The performance of two kinds of patterns all is higher than the performance (1ms at least) of the circuit that J.Schr der etc. proposes.

Sensor drive that the utility model proposes and signal picker also are applicable to the resonant transducer of other type.Be lower than the resonant transducer of 10MHz [as tuning fork, torsional resonances sensor, semi-girder resonant transducer, low frequency vibrating diaphragm resonant transducer, magnetostriction resonant transducer, low frequency flexural plate wave (Flexural Plate Wave for resonance frequency, FPW) sensor etc.], the circuit that the foregoing description proposed can not add the direct application of change.For resonance frequency greater than 10MHz, and less than the resonant transducer of 50MHz [as surface acoustic wave (Surface Acoustic Wave, SAW) sensor, high frequency FPW sensor, high-frequency diaphragm resonant transducer, the dull and stereotyped mould of sound (Acoustic Plate Mode, APM) sensor, magnetosonic resonant transducer (Magnetic-acoustic-resonator sensors, MARS) etc.], then in the physical circuit selected chip, element etc. different with the foregoing description.For example, the DDS in the circuit should select the higher chip of sample frequency for use, and slew rate of multiplier and transport and placing device (Slew Rate) and unity gain bandwidth dynamic indicators such as (Gain BandwidthProduct) satisfy the requirement of frequency applications.

Claims (1)

1, a kind of driving of resonant transducer and signal picker is characterized in that: whole driving and signal picker circuit comprise that sinusoidal signal produces circuit (1), sensor drive driving circuit (2), collection of simulant signal and treatment circuit (3), digital signal acquiring is handled and control circuit (4) four parts; Wherein, sinusoidal signal produces circuit and is made up of Direct Digital signal synthesis chip DDS, automatic gaining controling chip AGC and level and impedance transformation operational amplifier A mp1; Sensor drive driving circuit is made up of operational amplifier A mp2 and Amp3, sensor, reference resistance R1 and R2 and R3; Collection of simulant signal and treatment circuit are made up of analog multiplier MLPR1 and MLPR2, low-pass filter LPF1 and LPF2 and level conversion operational amplifier A mp4 and Amp5; Digital signal acquiring is handled and control circuit is made up of multi-way switch MUX, analog to digital converter ADC and central processor CPU; The input end of DDS links to each other with the control port of CPU; DDS, AGC link to each other in proper order with Amp1 then; The output terminal of Amp1 links to each other with the input end of sensor, the input end of R2 simultaneously; The output terminal of sensor and R2 links to each other with the inverting input of Amp2, Amp3 respectively; The in-phase end of Amp2, Amp3 is ground connection simultaneously, and reference resistance R2 and R3 then are connected across respectively between the output terminal and inverting input of operational amplifier A mp2 and Amp3; The output terminal of Amp2, Amp3 links to each other with the X input end with the Y input end of multiplier MLPR2 respectively; The output terminal of Amp2 then also links to each other with the Y input end with the X input end of multiplier MLPR1 simultaneously; The output terminal of two analog multiplier MLPR1 and MLPR2 links to each other with Amp5 with Amp4, LPF2 in proper order with LPF1 respectively; The output terminal of Amp4, Amp5 links to each other with two different input ends of multi-way switch MUX respectively, and the input end of analog signal of two corresponding output termination analog to digital converter ADC of multi-way switch; The numerical data output port of ADC links to each other with the numerical data input port of central processor CPU; The control port of CPU also links to each other with the channel selecting port of multi-way switch MUX and the control input end of ADC respectively.

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