CN110207891A - A kind of silicon micro resonance type pressure sensor closed loop detection system - Google Patents
A kind of silicon micro resonance type pressure sensor closed loop detection system Download PDFInfo
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- CN110207891A CN110207891A CN201910390213.2A CN201910390213A CN110207891A CN 110207891 A CN110207891 A CN 110207891A CN 201910390213 A CN201910390213 A CN 201910390213A CN 110207891 A CN110207891 A CN 110207891A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L25/00—Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
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Abstract
The invention discloses a kind of silicon micro resonance type pressure sensor closed loop detection systems, including analog module and digital circuit blocks, the analog module is by pre-amplifying module, signal processing module and excitation module composition, the digital circuit blocks are by analog-to-digital conversion module, all-digital phase-locked loop module and D/A converter module composition, the pre-amplifying module is made of detection circuit and filtering and amplifying circuit, the signal processing module is made of phase shifter, the all-digital phase-locked loop module is by frequency divider, digital phase discriminator, digital loop filters and digital controlled oscillator composition.The invention avoids the complexity of circuit structure existing for analog circuit, signal anti-interference is weak, wave distortion, the disadvantages of null offset, compared to analog phase-locked look, frequency divider can be configured according to input signal difference, meet two divided-frequency, three frequency division etc. is not easily susceptible to the influence of ambient temperature and voltage, and interference free performance is stronger and has higher precision.
Description
Technical field
The present invention relates to resonance type pressure sensor technical fields more particularly to a kind of silicon micro resonance type pressure sensor to close
Ring detection system.
Background technique
After the nineties in last century, using the silicon micro resonance type pressure sensor of monocrystalline silicon material and miromaching
It has gradually developed.Silicon micro resonant sensor major advantage has: first is that measurement accuracy is the major parameter of sensor, and frequency
With the period compared to resistance value, capacitance etc., there is higher measurement accuracy, be optimal measurement object；Second is that as one
Signal, frequency signal have stronger anti-interference ability compared to amplitude signal；Third is that silicon micro resonance type pressure sensor test essence
Degree is mainly influenced by resonance micro-structure mechanical performance, the existing influence of temperature drift and circuit noise to its measurement accuracy itself
It is the influence much smaller than structural-mechanical property, from measurement overall accuracy just it is found that pressure resistance type and measurement by capacitance overall accuracy are usual only
0.1% can be reached, and it is 0.01% that resonant silicon microsensor, which generally can reach measurement overall accuracy,.
The excitation of silicon micro resonance type pressure sensor has open-loop excitation and closed loop to motivate two kinds.Open-loop excitation is to sensor
Applying an excitation identical with resonator resonance frequency in sensor makes it with intrinsic frequency starting of oscillation.The advantages of open-loop excitation, exists
It is relatively simple in exciting circuit, and disadvantage is that input stimulus cannot follow the variation of resonator resonance frequency automatically and change,
This brings larger impact to the detection of silicon micro resonance type pressure sensor.Resonance frequency measurement essence can be improved in closed loop mode of operation
Degree and speed, range extension, and the dynamic characteristic of system can be improved.Using closed loop Resonant tube frequency detection circuit, work as ring
When the pressure change of border, by the feedback effect of closed-loop system, the output frequency of resonator can be responded correspondingly, automatically be made
Resonator is in resonant state always, and output signal can automatically real-time reflect the information of tested parameter, improve system
Sensitivity and measurement accuracy.
The closed-loop system of resonance type pressure sensor can be divided into self-oscillation, automatic growth control, three kinds of phaselocked loop.Self-excitation
Oscillation closed loop is to constitute feedback closed loop by adjusting the DC component of driving electrostatic force, and automatic gain control loop is to pass through control
System drives the AC compounent of electrostatic force to constitute feedback closed loop, and phase-locked loop is to realize close loop resonance by locking phase.Mesh
The preceding closed loop autonomous system based on phaselocked loop can only tracking frequency variation and the variation of phase can not be tracked, be easily destroyed closed loop
Phase condition needed for system maintains self-excitation state.If the later difference of phase lock loop locks is not fixed, each resonance
The variation of frequency all can cause the phase of system to change, reduce system stability and output signal frequency it is reliable
Property.
The prior art mostly uses greatly the mode of analog circuit regardless of being still based on PHASE-LOCKED LOOP PLL TECHNIQUE based on automatic growth control
Either part uses digital circuit, all existing some disadvantages, such as circuit structure complicated, and signal anti-interference is weak, waveform
Distortion, null offset etc..
Summary of the invention
To solve problems of the prior art, the present invention provides a kind of inspections of silicon micro resonance type pressure sensor closed loop
Examining system solves the problems, such as to mention in above-mentioned background technique.
To achieve the above object, the invention provides the following technical scheme: a kind of silicon micro resonance type pressure sensor closed loop is examined
Examining system, including analog module and digital circuit blocks, the analog module is by pre-amplifying module, signal processing
Module and excitation module composition, the digital circuit blocks are by analog-to-digital conversion module, all-digital phase-locked loop module and digital-to-analogue conversion
Module composition, the pre-amplifying module are made of detection circuit and filtering and amplifying circuit, and the signal processing module is by phase shift
Device composition, the all-digital phase-locked loop module is by frequency divider, digital phase discriminator, digital loop filters and digital controlled oscillator group
At the small-signal of the resonator output after testing amplified by filtering and amplifying circuit again by circuit detection, and filtering clutter is simultaneously
Tailored waveforms are adjusted by phase of the phase shifter to system, and signal is input to digital phase detection after analog-to-digital conversion module
Device, the feedback signal in digital phase discriminator with digital controlled oscillator output compare, and detect the two phase difference, and will test
Phase signal out is converted into voltage signal output, and signal is filtered by digital loop filters, then acts on numerical control vibration
Swing device, the output signal of digital controlled oscillator first pass around frequency divider by signal two divided-frequency using D/A converter module conversion again into
Enter excitation module, reduces after its amplitude as pumping signal excitation resonator, realize the all-digital phase-locked loop closed loop inspection of sensor
Examining system.
Preferably, the detection circuit in the pre-amplifying module is across resistance amplification detection circuit.
Preferably, the filtering and amplifying circuit in the pre-amplifying module is by a voltage controlled voltage source second order bandpass filtering
What circuit and three unlimited gain multiple feedback bandwidth-limited circuits formed.
Preferably, the digital phase discriminator in the all-digital phase-locked loop module is lead-lag phase discriminator.
Preferably, the digital loop filters in the all-digital phase-locked loop module mainly use PI to control, single by modulation
Member, proportional unit, integral unit and addition unit composition.
Preferably, the digital controlled oscillator in the all-digital phase-locked loop module is realized by accumulator.
Preferably, the all-digital phase-locked loop module is to be realized using verilog HDL Programming with Pascal Language using FPGA
's.
Preferably, the analog-to-digital conversion module is realized with ADC0804 chip.
Preferably, the D/A converter module is realized with AD5721 chip.
Preferably, the excitation module is built by two-stage reverse phase scaling circuit.
The beneficial effects of the present invention are: avoiding some disadvantages existing for analog circuit, such as circuit structure is complicated, signal is anti-
Interference is weak, wave distortion, null offset etc., and the frequency divider in all-digital phase-locked loop can be set according to input signal difference
It sets, meets such as two divided-frequency, three frequency division etc., all-digital phase-locked loop is not easily susceptible to the influence of ambient temperature and voltage, anti-interference
It can be stronger and with higher precision.
Detailed description of the invention
Fig. 1 is silicon micro resonance type pressure sensor closed loop detection system block diagram；
Fig. 2 is across resistance amplification detection circuit schematic diagram；
Fig. 3 is filtering and amplifying circuit figure；
Fig. 4 is voltage controlled voltage source second order bandwidth-limited circuit figure；
Fig. 5 is unlimited gain multiple feedback bandwidth-limited circuit figure；
Fig. 6 is digital loop filters structure chart；
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment shall fall within the protection scope of the present invention.
Fig. 1-6 is please referred to, the present invention provides a kind of technical solution: a kind of silicon micro resonance type pressure sensor closed loop detection system
System, including analog module and digital circuit blocks, the analog module is by pre-amplifying module, signal processing module
It is formed with excitation module, the digital circuit blocks are by analog-to-digital conversion module, all-digital phase-locked loop module and D/A converter module
Composition, the pre-amplifying module are made of detection circuit and filtering and amplifying circuit, and the signal processing module is by phase shifter group
At the all-digital phase-locked loop module is made of frequency divider, digital phase discriminator, digital loop filters and digital controlled oscillator, institute
Stating the small-signal that resonator exports, circuit detection is amplified by filtering and amplifying circuit again after testing, and filtering clutter simultaneously modifies wave
Shape is adjusted by phase of the phase shifter to system, and signal is input to digital phase discriminator after analog-to-digital conversion module, in number
Feedback signal in digit phase discriminator with digital controlled oscillator output compares, and detects the two phase difference, and the phase that will test out
Potentiometer signal is converted into voltage signal output, and signal is filtered by digital loop filters, then acts on digital controlled oscillator, number
The output signal of control oscillator first passes around frequency divider and signal two divided-frequency is entered back into excitation using D/A converter module conversion
Module reduces after its amplitude as pumping signal excitation resonator, realizes the all-digital phase-locked loop closed loop detection system of sensor.
Detection circuit in the pre-amplifying module be across resistance amplification detection circuit, across resistance amplification detection circuit in,
It is available by formula Q (t)=C (t) × V (t) to be by the electric current of sensor for micro- capacitor ultrasonic sensor
When sensor is in reception state, extraneous applies DC offset voltage, therefore first item is zero, at this time sensor
The transient current i generated when by ultrasonic wave acoustic pressure(t)It can be represented simply as
This transient current is linked into the input terminal of trans-impedance amplifier, then the output end in amplifier will generate instantaneously
Voltage, if the capacitance high speed of capacitance sensor changes, trans-impedance amplifier will export the voltage value of consecutive variations, output electricity
The size of pressure value is not only related with the capacitance change of capacitance sensor, also related with transfiguration rate of change, the voltage letter of output
Number calculation formula is
It is illustrated in figure 2 the schematic diagram of trans-impedance amplifier detection circuit, wherein UiIt (s) is DC offset voltage, CsFor sensing
The Equivalent Static capacitor of device, C1With C2For anti-stray capacitance, if it between parallel two conducting wire of pcb board the same face,
Valuation is 50pF, therefore the circuit can effectively inhibit the influence of stray capacitance；RfFor feedback resistance, formed with amplifier instrument negative
Feedback is played a leading role in C/V conversion, is mainly detected capacitance variations across resistance amplification detection circuit, is realized capacitor to electricity
The conversion of pressure.Small capacitance variable quantity can be measured across resistance amplification detection circuit, sensitivity is up to 1.64mV/fF, detection accuracy
It is higher compared to other methods.
Voltage controlled voltage source second order bandwidth-limited circuit figure as shown in Figure 4, the bandpass filter include the second amplifier A2
And resistance R~resistance R4, the resistance R1 one terminate instrument amplifier 2 output end, the other end of resistance R1 respectively with
Resistance R3, capacitor C4, capacitor C5 one end be connected, the other end of capacitor C5 normal phase input end, the electricity with the second amplifier A2 respectively
The one end for hindering R2 is connected, and the inverting input terminal of the second amplifier A2 is connected with one end of resistance R, resistance R4 respectively, capacitor C4, resistance
R, altogether, the other end of resistance R4, the other end of resistance R3 meet the output end of the second amplifier A2, and the second amplifier A2 to resistance R2
Output end of the output end as bandpass filter.
Bandpass filter is mainly used to filtering clutter and tailored waveforms, due to containing very in the output signal of micro-resonator
The noise of more different frequencies causes output waveform more mixed and disorderly, and a good incoming wave can not be provided for all-digital phase-locked loop
Shape can not work normally phaselocked loop, so the voltage controlled voltage source type second order band logical high using input impedance, output impedance is low is filtered
Wave device.Wherein resistance R1 and capacitor C4 composition low-pass filter network, resistance R2 and capacitor C5 composition high-pass filter network, two
Person's series connection just constitutes bandwidth-limited circuit, and resistance R, resistance R4 and the second amplifier A2 constitute in-phase proportion amplifying circuit,
Gain is Avt=1+R4/R, quality factor q=1/ (3-Avt).
Unlimited gain multiple feedback bandwidth-limited circuit figure as shown in Figure 5, R7 and C6 constitutes two feedback branches in figure,
Feedback is strong and weak related with signal frequency, and the gain of ideal operational amplificr is infinity, because of referred to herein as unlimited gain multiple feedback
Filter circuit.
Filtering and amplifying circuit in the pre-amplifying module be by a voltage controlled voltage source second order bandwidth-limited circuit and
What three unlimited gain multiple feedback bandwidth-limited circuits formed.Unlimited gain multiple feedback bandwidth-limited circuit has high
Selective and precipitous intermediate zone, but passband amplification factor is smaller, and voltage controlled voltage source second order bandwidth-limited circuit may be implemented
Biggish passband amplification factor, the digital phase discriminator in the all-digital phase-locked loop module is lead-lag phase discriminator.
Digital loop filters in the all-digital phase-locked loop module mainly use PI to control, by modulation unit, ratio
Unit, integral unit and addition unit composition, wherein modulation unit need by digital phase discriminator export " anticipating signal " and
" delay signal " is modulated with matching ratio-integral element, by or door and can be realized with door；Proportional unit passes through modulation
The adjusting of unit output sequence can obtain；Integral unit is realized by adding up to digital phase discriminator output sequence using accumulator；Two
The addition unit of person is realized using full adder.
Digital controlled oscillator in the all-digital phase-locked loop module is realized by accumulator, the digital locking phase
Ring moulds block is realized using FPGA, the analog-to-digital conversion module is to use ADC0804 using verilog HDL Programming with Pascal Language
For chip come what is realized, the D/A converter module is realized with AD5721 chip, and the frequency divider passes through frequency dividing electricity
Road is realized, can be configured according to input signal difference, and such as two divided-frequency, three frequency division etc. are met.
The excitation module is built by two-stage reverse phase scaling circuit, and the main function of excitation module is
Phase-locked loop circuit output signal is handled, emphasis is to reduce its amplitude to meet resonator input requirements.
Although the present invention is described in detail referring to the foregoing embodiments, for those skilled in the art,
It is still possible to modify the technical solutions described in the foregoing embodiments, or part of technical characteristic is carried out etc.
With replacement, all within the spirits and principles of the present invention, any modification, equivalent replacement, improvement and so on should be included in this
Within the protection scope of invention.
Claims (10)
1. a kind of silicon micro resonance type pressure sensor closed loop detection system, it is characterised in that: including analog module and number
Circuit module, the analog module are made of pre-amplifying module, signal processing module and excitation module, the number electricity
Road module is made of analog-to-digital conversion module, all-digital phase-locked loop module and D/A converter module, and the pre-amplifying module is by examining
Slowdown monitoring circuit and filtering and amplifying circuit composition, the signal processing module is made of phase shifter, the all-digital phase-locked loop module by
The small-signal of frequency divider, digital phase discriminator, digital loop filters and digital controlled oscillator composition, the resonator output is passed through
Detection circuit detection is amplified by filtering and amplifying circuit again, filtering clutter and tailored waveforms, by phase shifter to the phase of system
It is adjusted, signal is input to digital phase discriminator after analog-to-digital conversion module, defeated with digital controlled oscillator in digital phase discriminator
Feedback signal out compares, and both detects phase difference, and to be converted into voltage signal defeated for the phase signal that will test out
Out, signal is filtered by digital loop filters, then acts on digital controlled oscillator, the output signal of digital controlled oscillator passes through first
It crosses frequency divider and signal two divided-frequency is entered back into excitation module using D/A converter module conversion, reduce after its amplitude as excitation
Signal excitation resonator realizes the all-digital phase-locked loop closed loop detection system of sensor.
2. silicon micro resonance type pressure sensor closed loop detection system according to claim 1, it is characterised in that: described preposition
Detection circuit in amplification module is across resistance amplification detection circuit.
3. silicon micro resonance type pressure sensor closed loop detection system according to claim 1, it is characterised in that: described preposition
Filtering and amplifying circuit in amplification module is by a voltage controlled voltage source second order bandwidth-limited circuit and three unlimited gain multichannels
Feed back bandwidth-limited circuit composition.
4. silicon micro resonance type pressure sensor closed loop detection system according to claim 1, it is characterised in that: described total
Digital phase discriminator in word phase-locked loop module is lead-lag phase discriminator.
5. silicon micro resonance type pressure sensor closed loop detection system according to claim 1, it is characterised in that: described total
Digital loop filters in word phase-locked loop module mainly use PI to control, and by modulation unit, proportional unit, integral unit and add
Method unit composition.
6. silicon micro resonance type pressure sensor closed loop detection system according to claim 1, it is characterised in that: described total
Digital controlled oscillator in word phase-locked loop module is realized by accumulator.
7. silicon micro resonance type pressure sensor closed loop detection system according to claim 1, it is characterised in that: described is complete
Digital phase-locked loop module is to be realized using ver i l og HDL Programming with Pascal Language using FPGA.
8. silicon micro resonance type pressure sensor closed loop detection system according to claim 1, it is characterised in that: the mould
Number conversion module is realized with ADC0804 chip.
9. silicon micro resonance type pressure sensor closed loop detection system according to claim 1, it is characterised in that: the number
Mould conversion module is realized with AD5721 chip.
10. silicon micro resonance type pressure sensor closed loop detection system according to claim 1, it is characterised in that: described
Excitation module is built by two-stage reverse phase scaling circuit.
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Cited By (3)
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| CN113030515A (en) * | 2021-03-11 | 2021-06-25 | 东南大学 | Device for directly measuring amplitude ratio of weak coupling resonator |
| CN113124744A (en) * | 2021-04-20 | 2021-07-16 | 电子科技大学 | Intelligent intervertebral trial mold, implant and control method |
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