WO2021022459A1 - 电桥传感器的检测电路、芯片及检测*** - Google Patents

电桥传感器的检测电路、芯片及检测*** Download PDF

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Publication number
WO2021022459A1
WO2021022459A1 PCT/CN2019/099316 CN2019099316W WO2021022459A1 WO 2021022459 A1 WO2021022459 A1 WO 2021022459A1 CN 2019099316 W CN2019099316 W CN 2019099316W WO 2021022459 A1 WO2021022459 A1 WO 2021022459A1
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Prior art keywords
bridge sensor
switch
detection circuit
excitation
voltage source
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PCT/CN2019/099316
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English (en)
French (fr)
Inventor
李国炮
蒋宏
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深圳市汇顶科技股份有限公司
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Priority to CN201980004034.9A priority Critical patent/CN111051820B/zh
Priority to PCT/CN2019/099316 priority patent/WO2021022459A1/zh
Priority to EP19920638.4A priority patent/EP3957958B1/en
Priority to US17/060,015 priority patent/US11686598B2/en
Publication of WO2021022459A1 publication Critical patent/WO2021022459A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/16—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying resistance
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only
    • H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
    • H03F3/45475—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using IC blocks as the active amplifying circuit
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R17/00—Measuring arrangements involving comparison with a reference value, e.g. bridge
    • G01R17/10—AC or DC measuring bridges
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
    • G05B19/042—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using digital processors
    • G05B19/0428—Safety, monitoring
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H03K17/945—Proximity switches
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/20—Pc systems
    • G05B2219/26—Pc applications
    • G05B2219/2612—Data acquisition interface
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/129—Indexing scheme relating to amplifiers there being a feedback over the complete amplifier
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/261—Amplifier which being suitable for instrumentation applications
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/321—Use of a microprocessor in an amplifier circuit or its control circuit
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45116—Feedback coupled to the input of the differential amplifier
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45138—Two or more differential amplifiers in IC-block form are combined, e.g. measuring amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45528—Indexing scheme relating to differential amplifiers the FBC comprising one or more passive resistors and being coupled between the LC and the IC
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
    • H03K2217/94—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated
    • H03K2217/9401—Calibration techniques
    • H03K2217/94031—Calibration involving digital processing

Definitions

  • This application relates to the field of detection technology, and in particular to a detection circuit, chip, and detection system of a bridge sensor.
  • Bridge sensors are often used as sensing elements for pressure, temperature and other sensors. They are widely used in machinery, automobiles and other transportation, electrical, electrical, civil engineering, medicine, food and other fields; because of their good linear characteristics and can be used To be very thin, in recent years, the application in the field of human-computer interaction has become more and more extensive, such as touch screen pressure detection, electronic product button pressure detection, optical fingerprint pressure detection, smart watch pressure detection, etc.
  • the bridge sensor when a resistance strain gauge is used to form a bridge sensor for pressure detection, the bridge sensor can be installed on a specific surface of the elastic element. When the elastic element is strained, the resistance value of the resistance strain gauge will change slightly, which will be processed by the bridge circuit. Output in the form of electrical signals, this is the working principle of the bridge pressure sensor.
  • a DC voltage source or a DC current source is applied to the bridge, and the voltage signal output by the bridge is processed by a processing circuit to obtain pressure data or temperature data.
  • the purpose of some embodiments of the present application is to provide a detection circuit, chip, and detection system of a bridge sensor, which can greatly suppress the white noise of the system, improve the signal-to-noise ratio of the system, and thereby improve the detection performance of the bridge sensor.
  • An embodiment of the application provides a detection circuit for a bridge sensor, including: an AC excitation module, and a signal conditioning module, an analog-to-digital conversion module, and a processing module connected in sequence; the AC excitation module is used to apply to the bridge sensor AC excitation signal; the signal conditioning module and the analog-to-digital conversion module are used to sequentially process the output signal of the bridge sensor; the processing module is used to demodulate the processed output signal, and Obtain the detection information of the bridge sensor according to the demodulated output signal.
  • the embodiment of the present application also provides a chip, including: the detection circuit of the above-mentioned bridge sensor.
  • An embodiment of the present application also provides a detection system, including: a bridge sensor and a detection circuit of the above-mentioned bridge sensor.
  • the embodiment of the application adopts an AC excitation signal for the bridge sensor; since the bandwidth of the signal extracted in the demodulation of the AC signal is narrow, the white noise of the system can be greatly suppressed and the system signal-to-noise ratio can be improved. Thereby improving the detection sensitivity of the bridge sensor; and, the demodulation of the AC signal supports frequency hopping, which can avoid the interference frequency band of strong external noise and greatly improve the reliability of the system in harsh environments.
  • the processing module processes the demodulated output signal based on the correlated double sampling technology to obtain the detection information of the bridge sensor.
  • the output signal is processed based on the correlated double sampling technology, which can eliminate the output signal offset caused by the low frequency noise in the bridge sensor and the detection circuit as much as possible, thereby improving the signal-to-noise ratio.
  • the AC excitation module includes a first DC voltage source, a second DC voltage source, and a first excitation for switching and connecting the first DC voltage source and the second DC voltage source to the bridge sensor.
  • the first switch at the application end; the processing module is used to control the first switch to perform a switching action; the output voltages of the first direct current voltage source and the second direct current voltage source are different.
  • the AC excitation module is a hardware circuit, through which the AC excitation signal is generated.
  • the AC excitation module further includes a second switch for switching and connecting the first DC voltage source and the second DC voltage source to the second excitation applying end of the bridge sensor; the processing module Used to control the second switch to perform a switching action; in the first state, the processing module controls the first direct current voltage source to be connected to the first excitation applying terminal through the first switch, and controls The second DC voltage source is connected to the second excitation application terminal through the second switch; in the second state, the processing module controls the second DC voltage source to be connected through the first switch To the first excitation applying terminal, and controlling the first direct current voltage source to be connected to the second excitation applying terminal through the second switch.
  • This embodiment provides a specific example of the hardware implementation of the AC excitation module.
  • the two excitation application terminals of the bridge sensor are switched at the same time input voltage, which can suppress power supply noise.
  • the voltages output by the first DC voltage source and the second DC voltage source are the same in magnitude and opposite in direction.
  • the two DC voltage sources used for switching and connecting to form an AC excitation signal output voltages of the same magnitude and opposite directions, which can maximize the effective voltage signal amount of the AC excitation signal.
  • the signal conditioning module includes an instrumentation amplifier and an anti-aliasing filter; the first input end of the instrumentation amplifier is connected to the output end of the bridge sensor, and the output end of the instrumentation amplifier is connected to the anti-aliasing filter.
  • the input end of the anti-aliasing filter is connected to the input end of the analog-to-digital conversion module.
  • the signal conditioning module further includes a cancellation circuit; the cancellation circuit is connected to the second input end of the instrumentation amplifier, and the cancellation circuit is configured to: when no external force acts on the bridge sensor, the The voltage value output by the instrumentation amplifier meets the preset requirements.
  • a new cancellation circuit is added to the signal conditioning module, which can offset the signal offset problem caused by the incomplete matching of each bridge arm in the bridge sensor as much as possible; thereby, it can reduce the matching degree of the bridge arm in the bridge sensor. It is required that the existing bridge sensors can achieve high-quality detection.
  • the instrumentation amplifier has two second input terminals;
  • the cancellation circuit includes a first direct current source, a second direct current source, and is used to combine the first direct current source and the second direct current source.
  • Source switching is connected to a third switch of one of the second input terminals, and a fourth switch for switching and connecting the first direct current source and the second direct current source to the other of the second input terminals Switch;
  • the processing module is used to control the third switch and the fourth switch to perform a switching action; the first direct current source and the second direct current source output currents of the same magnitude and opposite directions.
  • the processing module is configured to demodulate the processed output signal based on a quadrature demodulation technology.
  • the quadrature demodulation method is adopted, and the calculation amount is small.
  • Fig. 1 is a schematic diagram of a detection circuit of a bridge sensor according to a first embodiment of the present application
  • FIG. 2 is a specific circuit diagram of the detection circuit of the bridge sensor according to the first embodiment of the present application.
  • Fig. 3 is a specific circuit diagram of the instrumentation amplifier according to the first embodiment of the present application.
  • FIG. 4 is a specific circuit diagram of the detection circuit of the bridge sensor according to the second embodiment of the present application.
  • Fig. 5 is a schematic diagram of a signal conditioning module including a cancellation circuit according to a fourth embodiment of the present application.
  • Fig. 6 is a schematic diagram of a timing waveform of a detection circuit according to a fourth embodiment of the present application.
  • Fig. 7 is an equivalent diagram of the detection circuit at a certain moment in the fourth embodiment of the present application.
  • the first embodiment of the present application relates to a detection circuit of a bridge sensor.
  • the detection circuit 1 includes: an AC excitation module 11 and a signal conditioning module 12, an analog-to-digital conversion module 13, and a processing module 14 connected in sequence.
  • the AC excitation module 11 is used to apply AC excitation signals to the bridge sensor 2;
  • the signal conditioning module 12 and the analog-to-digital conversion module 13 are used to process the output signal of the bridge sensor 2 in sequence;
  • the processing module 14 is used to process the processed output
  • the signal is demodulated, and the detection information of the bridge sensor 2 is obtained according to the demodulated output signal.
  • the bridge sensor 2 may be a sensor with different functions.
  • the bridge sensor is, for example, a pressure sensor, where the detection information is a pressure value; or, the bridge sensor is, for example, a temperature sensor, where the detection information is a temperature value.
  • the detection circuit 1 is a part of the touch chip.
  • the bridge sensor 2 and the touch chip can be located on the PCB at the same time.
  • the detection circuit 1 outputs the detection information to the host.
  • the host can be the CPU or other control of electronic devices such as mobile phones or tablets. Device.
  • the bridge sensor 2 in this embodiment includes four bridge arms.
  • Each bridge arm can be a sensor composed of a resistance strain gauge.
  • the bridge sensor 2 has two excitation application ends, which are the first The excitation application terminal 21-1 and the second excitation application terminal 21-2; the bridge sensor 2 also has two output terminals, a first output terminal 21-3 and a second output terminal 21-4, respectively.
  • the two output terminals of the bridge sensor 2 output a differential output voltage Voffset.
  • the signal conditioning module 12 includes an instrumentation amplifier 121 and an anti-aliasing filter 122.
  • the instrumentation amplifier is represented by INA
  • the anti-aliasing filter is represented by AAF.
  • the instrumentation amplifier 121 has two first input terminals 121-1 and 121-2, which are connected to the two output terminals 21-3 and 21-4 of the bridge sensor 2 respectively.
  • the output end of the instrumentation amplifier 121 is connected to the input end of the anti-aliasing filter 122, and the output end of the anti-aliasing filter 122 is connected to the input end of the analog-to-digital conversion module 13, which is represented by ADC in the figure.
  • the instrumentation amplifier 121 also has two second input terminals 121-3, 121-4, and a resistor Rg is connected between the two second input terminals; the resistor Rg can be set outside the instrumentation amplifier 121 or integrated in the instrument Inside the amplifier 121.
  • the instrumentation amplifier 121 also has a third input terminal 121-5 for inputting a reference voltage Vref.
  • the reference voltage Vref is the common mode voltage provided by the subsequent circuit such as the analog-to-digital conversion module 13 in this embodiment, that is, the reference voltage Vref. It is a common reference point for the instrumentation amplifier 121 and the analog-to-digital conversion module 13.
  • the reference voltage Vref is zero, that is, the third input terminal 121-5 is grounded; for a single power supply instrumentation amplifier 121, the reference voltage Vref is half of the power supply voltage; The third input terminal 121-5 is grounded.
  • FIG. 2 is only an example, and the specific implementation of the signal conditioning module 2 is not limited in any way.
  • the detection circuit 1 is a part of the touch chip, where the bridge sensor 2 and the touch chip can be located on the PCB at the same time, and the detection circuit 1 outputs the detection information to the host.
  • the host can be the CPU or the CPU of an electronic device such as a mobile phone or a tablet. Other controllers.
  • the instrumentation amplifier 121 includes a first operational amplifier 1211, a second operational amplifier 1212, and a third operational amplifier 1213; the output terminal of the first operational amplifier 1211 is connected to the positive terminal of the third operational amplifier 1213.
  • Phase input terminal, the output terminal of the second operational amplifier 1212 is connected to the inverting input terminal of the third operational amplifier 1213; the non-inverting input terminal of the first operational amplifier 1211 and the non-inverting input terminal of the second operational amplifier 1212 are used as the instrumentation amplifier 121
  • the two first input terminals 121-1, 121-2 of the two are respectively connected to the two output terminals 21-3, 21-4 of the bridge sensor 2; the inverting input terminal of the first operational amplifier 1211 and the second operational amplifier
  • the inverting input terminal of 1212 serves as the two second input terminals 121-3 and 121-4 of the instrumentation amplifier 121; the output terminal of the third operational amplifier 1213 serves as the output terminal of the instrumentation amplifier 121.
  • the resistor Rf is connected between the inverting input terminal and the output terminal of the first operational amplifier 1211, the resistor Rf is connected between the inverting input terminal and the output terminal of the second operational amplifier 1212, and the inverting input terminal of the third operational amplifier 1213 is connected.
  • a resistor R1, the output terminal of the first operational amplifier 1211 and the non-inverting input terminal of the third operational amplifier 1213 are connected to the output terminal, and the resistor R1, the output terminal of the second operational amplifier 1212, and the third operational amplifier 1213 are connected between
  • a resistor R1 is connected between the inverting input terminals of the third operational amplifier 1213 and a resistor R1 is connected between the non-inverting input terminal of the third operational amplifier 1213 and the third input terminal 121-5.
  • the AC excitation module 11 is used to generate AC excitation signals.
  • the AC excitation module 11 may be a signal generator for generating AC voltage signals or AC current signals, or a hardware circuit for generating AC voltage signals or AC current signals. .
  • the AC excitation module 11 is a hardware circuit. Please refer to FIG. 2. It includes a first DC voltage source VDD, a second DC voltage source VSS, and the first DC voltage source VDD and the second DC voltage source VSS.
  • the first switch K1 connected to the first excitation applying terminal 21-1 of the bridge sensor 2 is switched. Wherein, the voltages output by the first DC voltage source VDD and the second DC voltage source VSS are different.
  • the first switch K1 is, for example, a single-pole double-throw switch.
  • the second excitation application terminal 21-2 is connected to a preset DC voltage source Vm, wherein the magnitude of the voltage output by the preset DC voltage source Vm is between the first DC voltage source VDD and the second DC voltage source VDD. Between the magnitude of the voltage output by the DC voltage source VSS.
  • the processing module 14 is used to control the first switching switch K1 to perform a switching action, so that the first DC voltage source VDD is connected to the first excitation applying terminal 21-1 through the first switching switch K1, or the second DC voltage source VSS passes through the A switch K1 is connected to the first excitation applying terminal 21-1.
  • connecting the first DC voltage source VDD to the first excitation applying terminal 21-1 is marked as the detection circuit being in the first state; connecting the second DC voltage source VSS to the first excitation applying terminal 21-1 is marked as The detection circuit is in the second state.
  • the control signal used by the processing module 14 to control the first switch S1 to realize the switching action may be periodically changed, such as a square wave signal.
  • VDD difference between VDD and Vm
  • VSS difference between Vm and VSS
  • Vm difference between Vm and VSS
  • the processing module 14 controls the first switching switch S1 to realize the switching action.
  • the control signal is a square wave signal
  • the AC excitation signal output by the AC excitation module 11 is also a square wave signal.
  • the differential output signal Voffset output by the bridge sensor 2 is an analog signal and includes two parts, one is a high-frequency AC excitation signal, and the other is a low-frequency DC signal; the DC signal includes the signal that acts on the bridge sensor 2. Superposition of external force and noise of the entire circuit. Therefore, the AC excitation signal can be understood as a modulation signal of the DC signal to assist in the transmission of the DC signal; the frequency of the AC excitation signal can be selected according to needs, and the frequency of the AC excitation signal is realized by the processing module 14 controlling the first switch S1 The frequency of the control signal for the switching action is determined.
  • the output signal Voffset of the bridge sensor 2 is amplified by the instrumentation amplifier 121, filtered by the anti-aliasing filter, and then digital-to-analog conversion is performed by the analog-to-digital conversion module 13 to obtain the output signal in digital form.
  • the processing module 14 is used to demodulate the output signal in digital form, and obtain the detection information of the bridge sensor according to the demodulated output signal. Among them, the processing module 14 demodulates the digital output signal based on the quadrature demodulation technology, thereby reducing the amount of calculation and reducing the burden of the processing module.
  • the processing module 14 includes a DPS processor 141 and a microprocessor 142; the DPS processor 141 is used to demodulate the output signal in digital form, and the microprocessor 142 is used to demodulate the output signal according to the demodulation.
  • the detection information of the bridge sensor 2 is obtained, and the detection information is, for example, a pressure value or a temperature value; the microprocessor 142 is also used to control the switching action of the first switch K1.
  • the processing module 14 may also only include the microprocessor 142, and the microprocessor 142 implements the demodulation function.
  • the embodiment of the present application uses an AC excitation signal for the bridge sensor 2.
  • the AC signal is demodulated, only useful information is extracted near the frequency of the AC signal, that is, the signal bandwidth involved in demodulation is relatively low. Narrow, can greatly suppress the white noise of the system, improve the signal-to-noise ratio of the system, thereby improving the detection sensitivity of the bridge sensor; and, the demodulation of the AC excitation signal supports frequency hopping, that is, the frequency of the AC excitation signal as the modulation signal can be selected as required , Which can avoid the interference frequency band of strong external noise and greatly improve the reliability of the system in harsh environments.
  • the second embodiment of the present application relates to a detection circuit of a bridge sensor.
  • the second embodiment differs from the first embodiment in that, as shown in FIG. 4, the AC excitation module 11 further includes a second switch K2, and the second switch K2 is used to switch the first DC voltage source VDD, the second The direct current voltage source VSS is switched and connected to the second excitation application terminal 21-2 of the bridge sensor 2.
  • the processing module 14 is used to control the second switch K2 to perform the switching action; in the first state, the processing module 14 also controls the second DC voltage source VSS to be connected to the second excitation application terminal 21-2 through the second switch K2, In the second state, the processing module 14 also controls the first DC voltage source VDD to be connected to the second excitation application terminal 21-1 through the second switch K2.
  • the processing module 14 is configured to control the first switch K1 and the second switch K2 to periodically perform a switching action.
  • the processing module 14 controls the first switching switch K1 to act, so that the first DC voltage source VDD is connected to the first excitation applying terminal 21-1 through the first switching switch K1, and controls the second switching switch K2 is activated, so that the second DC voltage source VSS is connected to the second excitation applying terminal 21-2 through the second switch K2.
  • the detection circuit 1 is in the first state; in the second half cycle, the processing module 14 controls the first A switch K1 is activated so that the second DC voltage source VSS is connected to the first excitation applying terminal 21-1 through the first switch K1, and the second switch K2 is controlled to act so that the first DC voltage source VDD The second switch K2 is connected to the second excitation applying terminal 21-2, and the detection circuit 1 is in the second state at this time.
  • the processing module 14 may be used to control the first switch K1 and the second switch K2 to perform periodic switching.
  • the control signal may be a square wave signal.
  • the AC excitation signal output by the AC excitation module 11 is also a square wave signal.
  • the detection circuit 1 is a part of the touch chip.
  • the bridge sensor 2 and the touch chip can be located on the PCB at the same time.
  • the detection circuit 1 outputs the detection information to the host through the processing module 14.
  • the host can be an electronic device such as a mobile phone or a tablet. CPU or other controller.
  • the applied DC signals are switched at the two excitation application terminals at the same time to form an AC excitation signal.
  • This simultaneous switching on both sides can suppress the noise of the AC excitation module (DC power supply) itself and further improve the signal-to-noise ratio .
  • the voltages applied to the two excitation application terminals at the same time have the same magnitude and opposite directions, which can maximize the effective voltage signal amount of the AC excitation signal.
  • the third embodiment of the present application relates to a detection circuit of a bridge sensor.
  • the third embodiment is an improvement based on the first or second embodiment.
  • the improvement lies in that the processing module 14 processes the demodulated output signal Voffset based on the correlated double sampling technique to obtain the detection information of the bridge sensor 2. .
  • the offset in the circuit can be eliminated as much as possible, such as the offset voltage drift of the bridge sensor 2, its own 1/f noise and bad parasitic thermocouple effects, and the offset voltage of the instrumentation amplifier Drift and its own 1/f noise; thereby further reducing the low-frequency noise of the circuit and improving the signal-to-noise ratio.
  • the fourth embodiment of the present application relates to a detection circuit of a bridge sensor.
  • the fourth embodiment is an improvement based on the third embodiment.
  • the improvement is that, as shown in FIG. 5, the signal conditioning module 12 further includes a cancellation circuit 124; the cancellation circuit 124 is connected to the second input terminal of the instrumentation amplifier 121 121-3, 121-4, and the cancellation circuit 124 is configured to: when no external force acts on the bridge sensor 2, the voltage value output by the instrumentation amplifier 121 meets the preset requirement.
  • the cancellation circuit 124 includes a first direct current source, a second direct current source, a third switch K3, and a fourth switch K4.
  • the third switch K3 is used to switch one of the second input terminals 121-3 of the instrument amplifier 121 to the first direct current source and the second direct current source; the fourth switch K4 is used to switch the other of the instrument amplifier 121
  • the second input terminal 121-4 is switchably connected to the first direct current source and the second direct current source; wherein, the current output from the first direct current source and the second direct current source are the same in magnitude and opposite in direction.
  • the current size of the first DC current source and the current size of the second DC current source are both expressed by Icancel to reflect that the current sizes of the two are the same.
  • the first DC current source and the second DC current source are indicated by arrows in different directions different.
  • the first DC voltage source VSS is used as the power supply for the first DC current source
  • the second DC voltage source VDD is used as the power supply for the second DC current source; however, it is not limited to this, as long as it can be
  • the first direct current source and the second direct current source only need to provide suitable power supply; it should be noted that after the current size and direction of the first direct current source are determined, a suitable power supply can be selected for it; the second direct current source The same is true for current sources.
  • the processing module 14 is used to control the first switching switch K1, the second switching switch K2, the third switching switch K3, and the fourth switching switch K4 to periodically perform switching actions;
  • FIG. 6 shows the timing of the detection circuit in this embodiment.
  • Vo in FIG. 6 represents the output voltage of the instrumentation amplifier 121
  • AFF_Vout represents the output voltage of the anti-aliasing filter 122
  • t0 to t7 represent different times.
  • K1, K2, K3, and K4 are all set to end 0, and the detection circuit can be simplified as shown in Figure 7.
  • Vo-Vref V3-V4.
  • V3 V1+[(V1-V2)/Rg+Icancel]*Rf;
  • V4 V2–[(V1-V2)/Rg+Icancel]*Rf;
  • K1, K2, K3, and K4 are all set to end 1.
  • Icancel -Voffset*(2*Rf/Rg+1)/(2*Icancel)
  • the offset cancellation circuit 124 is used to offset the offset of the output voltage Voffset of the bridge sensor 2.
  • the magnitude and direction of the current of the first direct current source and the second direct current source can be adjusted until the detected output signal of the instrumentation amplifier 121 meets the preset requirements, which can be set It is determined that the difference between the output voltage of the instrumentation amplifier 121 and the reference voltage Vref input to the instrumentation amplifier 121 is zero, where the reference voltage Vref is the common mode voltage provided by the analog-to-digital conversion module 13.
  • the new cancellation circuit 124 in the signal conditioning module 12 of this embodiment can offset the signal offset problem caused by the incomplete matching of the bridge arms in the bridge sensor 2 as much as possible; thus, the degree of matching to the bridge arms in the bridge sensor can be reduced. For the existing bridge sensors, high-quality detection can be achieved.
  • the specific implementation of the cancellation circuit provided in this embodiment is only an example, and any circuit form that is equivalently deformed and can achieve the purpose of the cancellation circuit belongs to the scope of protection of the embodiment of the application.
  • the fourth embodiment may also be an improvement based on the first or second embodiment.
  • the fifth embodiment of the present application relates to a chip including the detection circuit of the bridge sensor described in any one of the first to fourth embodiments.
  • the sixth embodiment of the present application relates to a detection system including a bridge sensor and the detection circuit of the bridge sensor according to any one of the first to fourth embodiments.

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Abstract

一种电桥传感器(2)的检测电路(1)，包括交流激励模块(11)以及依次连接的信号调理模块(12)、模数转换模块(13)、处理模块(14)；交流激励模块(11)用于向电桥传感器(2)施加交流激励信号；信号调理模块(12)、模数转换模块(13)用于对电桥传感器(2)的输出信号依次进行处理；处理模块(14)用于对处理后的输出信号进行解调，并根据解调后的输出信号得到电桥传感器(2)的检测信息。还公开包括检测电路(1)的芯片及检测***。检测电路(1)可以大幅抑制***白噪声，提高***信噪比，从而提升电桥传感器(2)的检测性能。

Description

电桥传感器的检测电路、芯片及检测*** 技术领域
本申请涉及检测技术领域，特别涉及一种电桥传感器的检测电路、芯片及检测***。
背景技术
电桥传感器常被用作压力、温度等传感器的感应元件，广泛应用于机械、汽车等交通工具、电气、电机、土木建筑、医学、食品等领域；由于其具有很好的线性特性且可以做到非常薄，近年来在人机交互领域的应用也越来越广泛，如触控屏压力检测、电子产品按键压力检测、光学指纹压力检测、智能手表压力检测等。
如压力检测使用电阻应变片构成电桥传感器时，可将电桥传感器安装在弹性元件特定表面上，当弹性元件发生应变时，会引起电阻应变片电阻值发生微小变化，经电桥电路处理后以电信号的方式输出，这就是电桥式压力传感器的工作原理。传统的电桥传感器的检测电路中，给电桥施加直流电压源或直流电流源激励，将电桥输出的电压信号经处理电路处理后即可得到压力数据或温度数据。
发明内容
本申请部分实施例的目的在于提供一种电桥传感器的检测电路、芯片及检测***，可以大幅抑制***白噪声，提高***信噪比，从而提升电桥传感器的检测性能。
本申请实施例提供了一种电桥传感器的检测电路，包括：交流激励模块以及依次连接的信号调理模块、模数转换模块、处理模块；所述交流激励模块用于向所述电桥传感器施加交流激励信号；所述信号调理模块、所述模数转换模块用于对所述电桥传感器的输出信号依次进行处理；所述处理模块用于对处理后的所述输出信号进行解调，并根据解调后的所述输出信号得到所述电桥传感器的检测信息。
本申请实施例还提供了一种芯片，包括：上述电桥传感器的检测电路。
本申请实施例还提供了一种检测***，包括：电桥传感器以及上述电桥传感器的检测电路。
本申请实施例现对于现有技术而言，对电桥传感器采用交流激励信号；由于交流信号的解调中提取的信号的带宽较窄，从而可以大幅抑制***白噪声，提高***信噪比，从而提高电桥传感器的检测灵敏度；并且，交流信号的解调支持跳频，从而可避开外界强噪声干扰频段、大幅提升***在恶劣环境下的可靠性。
例如，所述处理模块基于相关双采样技术对解调后的所述输出信号进行处理，得到所述电桥传感器的检测信息。本实施例中，基于相关双采样技术对输出信号进行处理，可以尽可能消除电桥传感器及检测电路中的低频噪声导致的输出信号偏移，从而提高信噪比。
例如，所述交流激励模块包括第一直流电压源、第二直流电压源以及用 于将所述第一直流电压源、所述第二直流电压源切换连接至所述电桥传感器的第一激励施加端的第一切换开关；所述处理模块用于控制所述第一切换开关执行切换动作；所述第一直流电压源和所述第二直流电压源输出的电压不相同。本实施例中，交流激励模块是一个硬件电路，通过硬件电路来产生交流激励信号。
例如，所述交流激励模块还包括用于将所述第一直流电压源、所述第二直流电压源切换连接至所述电桥传感器的第二激励施加端的第二切换开关；所述处理模块用于控制所述第二切换开关执行切换动作；在第一状态中，所述处理模块控制所述第一直流电压源通过所述第一切换开关连接至所述第一激励施加端，且控制所述第二直流电压源通过所述第二切换开关连接至所述第二激励施加端；在第二状态中，所述处理模块控制所述第二直流电压源通过所述第一切换开关连接至所述第一激励施加端，且控制所述第一直流电压源通过所述第二切换开关连接至所述第二激励施加端。本实施例提供了交流激励模块的硬件实现方式的一个具体例子，对电桥传感器的两个激励施加端同时切换输入电压，能够抑制电源噪声。
例如，所述第一直流电压源和所述第二直流电压源输出的电压大小相同且方向相反。本实施例中，用于切换连接形成交流激励信号的两个直流电压源输出的电压大小相同且方向相反，能够最大程度地提高交流激励信号的有效电压信号量。
例如，所述信号调理模块包括仪表放大器和抗混叠滤波器；所述仪表放大器的第一输入端连接于所述电桥传感器的输出端，所述仪表放大器的输出端连接于所述抗混叠滤波器的输入端，所述抗混叠滤波器的输出端连接于所述模 数转换模块的输入端。所述信号调理模块还包括抵消电路；所述抵消电路连接于所述仪表放大器的第二输入端，且所述抵消电路被配置为：在无外力作用于所述电桥传感器的情况下，所述仪表放大器输出的电压值满足预设要求。本实施例中，在信号调理模块中新增抵消电路，可以尽可能抵消电桥传感器中由于各桥臂不完全匹配导致的信号偏移问题；从而可以降低对电桥传感器中桥臂匹配度的要求，对于已有的电桥传感器，都能实现高质量的检测。
例如，所述仪表放大器具有两个所述第二输入端；所述抵消电路包括第一直流电流源、第二直流电流源、用于将所述第一直流电流源、所述第二直流电流源切换连接至其中一个所述第二输入端的第三切换开关、以及用于将所述第一直流电流源、所述第二直流电流源切换连接至另一个所述第二输入端的第四切换开关；所述处理模块用于控制所述第三切换开关、所述第四切换开关执行切换动作；所述第一直流电流源、所述第二直流电流源输出的电流大小相同且方向相反。本实施例提供了抵消电路的一种具体实现方式。
例如，所述处理模块用于基于正交解调技术对处理后的所述输出信号进行解调。本实施例中采用正交解调方式，计算量较小。
附图说明
一个或多个实施例通过与之对应的附图中的图片进行示例性说明，这些示例性说明并不构成对实施例的限定，附图中具有相同参考数字标号的元件表示为类似的元件，除非有特别申明，附图中的图不构成比例限制。
图1是根据本申请第一实施例的电桥传感器的检测电路的示意图；
图2是根据本申请第一实施例的电桥传感器的检测电路的具体电路图；
图3是根据本申请第一实施例中仪表放大器的具体电路图；
图4是根据本申请第二实施例的电桥传感器的检测电路的具体电路图；
图5是根据本申请第四实施例中信号调理模块包括抵消电路的示意图；
图6是根据本申请第四实施例中检测电路的时序波形示意图；
图7是根据本申请第四实施例中某一时刻的检测电路的等效图。
具体实施方式
为了使本申请的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本申请部分实施例进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本申请，并不用于限定本申请。并且，以下各个实施例的划分是为了描述方便，不应对本发明的具体实现方式构成任何限定，各个实施例在不矛盾的前提下可以相互结合相互引用。
发明人发现现有技术至少存在以下问题：在消费类电子产品中，轻薄化是产品的一大亮点；然而在很轻薄的产品中，结构设计空间有限应变量极小，电桥电阻值变化小，电桥输出的电压信号也很小，此时处理电路的噪声会对电压信号产生较大影响，最终导致电桥传感器检测的准确度较低。
本申请第一实施例涉及一种电桥传感器的检测电路，如图1所示，检测电路1包括：交流激励模块11以及依次连接的信号调理模块12、模数转换模块13、处理模块14。交流激励模块11用于向电桥传感器2施加交流激励信号；信号调理模块12、模数转换模块13用于对电桥传感器2的输出信号依次进行处理；处理模块14用于对处理后的输出信号进行解调，并根据解调后的输出信号得到电桥传感器2的检测信息。其中，电桥传感器2可以是具有不同功能的 传感器，电桥传感器例如是压力传感器，此时检测信息是压力值；或者，电桥传感器例如是温度传感器，此时检测信息是温度值。检测电路1为触控芯片的一部分，其中电桥传感器2和触控芯片可以同时位于PCB板上，检测电路1将检测信息输出给主机，主机可以是手机或者平板等电子设备的CPU或者其它控制器。
如图2所示，本实施例中的电桥传感器2包括四个桥臂，每个桥臂可以是一个电阻应变片构成的传感器，电桥传感器2具有两个激励施加端，分别为第一激励施加端21-1和第二激励施加端21-2；电桥传感器2还具有两个输出端，分别是第一输出端21-3和第二输出端21-4。电桥传感器2的两个输出端输出差分形式的输出电压Voffset。
如图2中，信号调理模块12包括仪表放大器121和抗混叠滤波器122，图中仪表放大器以INA表示，抗混叠滤波器以AAF表示。仪表放大器121具有两个第一输入端121-1、121-2，分别连接于电桥传感器2的两个输出端21-3、21-4。仪表放大器121的输出端连接于抗混叠滤波器122的输入端，抗混叠滤波器122的输出端连接于模数转换模块13的输入端，图中模数转换模块以ADC表示。其中，仪表放大器121还具有两个第二输入端121-3、121-4，两个第二输入端之间连接有电阻Rg；该电阻Rg可以设置在仪表放大器121外，也可以集成在仪表放大器121内。仪表放大器121还具有第三输入端121-5，用于输入参考电压Vref，该参考电压Vref是后级电路如本实施例中的模数转换模块13提供的共模电压，即该参考电压Vref是仪表放大器121与模数转换模块13的一个共同的参考点。一般的，对于双电源供电的仪表放大器121，参考电压Vref为零，即第三输入端121-5接地；对于单电源供电的仪表放大器121，参 考电压Vref为电源电压的一半；图2中的第三输入端121-5接地。需要说明的是，图2只是一个例子，对信号调理模块2的具体实现方式不作任何限定。其中，检测电路1为触控芯片的一部分，其中电桥传感器2和触控芯片可以同时位于PCB板上，检测电路1将检测信息输出给主机，主机可以是手机或者平板等电子设备的CPU或者其它控制器。
在一个例子中，如图3所示，仪表放大器121包括第一运算放大器1211、第二运算放大器1212以及第三运算放大器1213；第一运算放大器1211的输出端连接于第三运算放大器1213的正相输入端，第二运算放大器1212的输出端连接于第三运算放大器1213的反相输入端；第一运算放大器1211的正相输入端和第二运算放大器1212的正相输入端作为仪表放大器121的两个第一输入端121-1、121-2，分别连接于电桥传感器2的两个输出端21-3、21-4；第一运算放大器1211的反相输入端和第二运算放大器1212的反相输入端作为仪表放大器121的两个第二输入端121-3、121-4；第三运算放大器1213的输出端作为仪表放大器121的输出端。第一运算放大器1211的反相输入端与输出端之间连接有电阻Rf、第二运算放大器1212的反相输入端与输出端之间连接有电阻Rf、第三运算放大器1213的反相输入端与输出端之间连接有电阻R1、第一运算放大器1211的输出端和第三运算放大器1213的正相输入端之间连接于电阻R1、第二运算放大器1212的输出端和第三运算放大器1213的反相输入端之间连接于电阻R1；第三运算放大器1213的正相输入端与第三输入端121-5之间连接有电阻R1。
交流激励模块11用于产生交流激励信号，交流激励模块11可以是一个用于产生交流电压信号或者交流电流信号的信号发生器，也可以是一个用于产 生交流电压信号或者交流电流信号的硬件电路。
本实施例中，交流激励模块11为一个硬件电路，请参考图2，包括第一直流电压源VDD、第二直流电压源VSS以及用于将第一直流电压源VDD、第二直流电压源VSS切换连接至电桥传感器2的第一激励施加端21-1的第一切换开关K1。其中，第一直流电压源VDD和第二直流电压源VSS输出的电压不相同。第一切换开关K1例如为单刀双掷开关。
在图2的例子中，第二激励施加端21-2连接至一个预设直流电压源Vm，其中，该预设直流电压源Vm输出的电压的大小介于第一直流电压源VDD和第二直流电压源VSS输出的电压的大小之间。例如VDD、VSS、Vm的取值可以为，VDD＝15v、VSS＝2v、Vm＝-5v；或者，VDD＝15v、VSS＝5v、Vm＝10v；或者，VDD＝5v、VSS＝-5v、Vm＝0v，即可以理解为第二激励施加端21-2接地。
处理模块14用于控制第一切换开关K1执行切换动作，以使得第一直流电压源VDD通过第一切换开关K1连接至第一激励施加端21-1，或者，第二直流电压源VSS通过第一切换开关K1连接至第一激励施加端21-1。本实施例中，将第一直流电压源VDD连接至第一激励施加端21-1记作检测电路处于第一状态；将第二直流电压源VSS连接至第一激励施加端21-1记作检测电路处于第二状态。其中，处理模块14用于控制第一切换开关S1实现切换动作的控制信号可以是周期性变化的，例如方波信号。如果VDD与Vm的差值等于Vm与VSS的差值，例如VDD＝5v、VSS＝-5v、Vm＝0v，并且处理模块14控制第一切换开关S1实现切换动作的控制信号为方波信号，那么交流激励模块11输出的交流激励信号也是方波信号。
电桥传感器2输出的差分形式的输出信号Voffset是一个模拟形式的信号 且包括两部分，一部分是高频的交流激励信号，另一部分是低频的直流信号；直流信号包括作用于电桥传感器2的外力和整个电路噪声的叠加。因此，交流激励信号可以理解为是直流信号的调制信号，用来辅助传输直流信号；交流激励信号的频率是可以根据需要选择的，交流激励信号的频率由处理模块14控制第一切换开关S1实现切换动作的控制信号的频率决定。
电桥传感器2的输出信号Voffset经仪表放大器121放大，再经抗混叠滤波器滤波后，由模数转换模块13进行数模转换，得到数字形式的输出信号。处理模块14用于对数字形式的输出信号进行解调，并根据解调后的输出信号得到电桥传感器的检测信息。其中，处理模块14基于正交解调技术对数字形式的输出信号进行解调，从而可以降低计算量，减轻处理模块的负担。
在图2的例子中，处理模块14包括DPS处理器141和微处理器142；DPS处理器141用于对数字形式的输出信号进行解调，微处理器142用于根据解调后的输出信号得到电桥传感器2的检测信息，检测信息例如为压力值或温度值；微处理器142还用于控制第一切换开关K1的切换动作。然并不以此为限，在其他例子中，处理模块14也可以只包含微处理器142，由微处理器142实现解调功能。
本申请实施例现对于现有技术而言，对电桥传感器2采用交流激励信号；由于交流信号的解调时，仅在交流信号频率点附近提取有用信息，即解调中涉及的信号带宽较窄，可以大幅抑制***白噪声，提高***信噪比，从而提高电桥传感器的检测灵敏度；并且，交流激励信号的解调支持跳频，即可以根据需要选择作为调制信号的交流激励信号的频率，从而可避开外界强噪声干扰频段、大幅提升***在恶劣环境下的可靠性。
本申请第二实施例涉及一种电桥传感器的检测电路。第二实施例与第一实施例的不同之处在于，如图4所示，交流激励模块11还包括第二切换开关K2，第二切换开关K2用于将第一直流电压源VDD、第二直流电压源VSS切换连接至电桥传感器2的第二激励施加端21-2。处理模块14用于控制第二切换开关K2执行切换动作；第一状态中，处理模块14还控制第二直流电压源VSS通过第二切换开关K2连接至第二激励施加端21-2，在第二状态中，处理模块14还控制第一直流电压源VDD通过第二切换开关K2连接至第二激励施加端21-1。
具体的，处理模块14用于控制第一切换开关K1、第二切换开关K2周期性地执行切换动作。在上半个周期内，处理模块14控制第一切换开关K1作动，以使得第一直流电压源VDD通过第一切换开关K1连接至第一激励施加端21-1，且控制第二切换开关K2作动，以使得第二直流电压源VSS通过第二切换开关K2连接至第二激励施加端21-2，此时检测电路1处于第一状态；在下半个周期内，处理模块14控制第一切换开关K1作动，以使得第二直流电压源VSS通过第一切换开关K1连接至第一激励施加端21-1，且控制第二切换开关K2作动，以使得第一直流电压源VDD通过第二切换开关K2连接至第二激励施加端21-2，此时检测电路1处于第二状态。
本实施例中，第一直流电压源VDD和第二直流电压源VSS输出的电压大小相同且方向相反；例如，VDD＝5v，VSS＝-5v。
处理模块14可以用于控制第一切换开关K1、第二切换开关K2进行周期性切换的控制信号可以为方波信号，此时，交流激励模块11输出的交流激励信号也是方波信号。检测电路1为触控芯片的一部分，其中电桥传感器2和触 控芯片可以同时位于PCB板上，检测电路1通过处理模块14将检测信息输出给主机，主机可以是手机或者平板等电子设备的CPU或者其它控制器。
本实施例中，在两个激励施加端同时切换施加的直流信号，以形成交流激励信号，这种两边同时切换的方式，能够抑制交流激励模块(直流电源)本身的噪声，进一步提高信噪比。并且，在同一时刻施加在两个激励施加端的电压大小相等且方向相反，能够最大程度地提高交流激励信号的有效电压信号量。
本申请第三实施例涉及一种电桥传感器的检测电路。第三实施例是在第一或二实施例基础上进行的改进，改进之处在于，处理模块14基于相关双采样技术对解调后的输出信号Voffset进行处理，得到电桥传感器2的检测信息。
本实施例中，采用相关双采样技术，可以尽可能消除电路中的偏移量，如电桥传感器2的失调电压漂移、自身的1/f噪声及不良寄生热电偶效应，仪表放大器的失调电压漂移及自身的1/f噪声；从而进一步降低电路低频噪声，提高信噪比。
本申请第四实施例涉及一种电桥传感器的检测电路。第四实施例是在第三实施例基础上进行的改进，改进之处在于，如图5所示，信号调理模块12还包括抵消电路124；抵消电路124连接于仪表放大器121的第二输入端121-3、121-4，且抵消电路124被配置为：在无外力作用于电桥传感器2的情况下，仪表放大器121输出的电压值满足预设要求。
在图5所示的例子中，抵消电路124包括第一直流电流源、第二直流电流源、第三切换开关K3以及第四切换开关K4。第三切换开关K3用于将仪表放大器121的其中一个第二输入端121-3切换连接至第一直流电流源、第二直流电流源；第四切换开关K4用于将仪表放大器121的另一个第二输入端121-4 切换连接至第一直流电流源、第二直流电流源；其中，第一直流电流源、第二直流电流源输出的电流大小相同且方向相反，本实施例中，将第一直流电流源的电流大小、第二直流电流源的电流大小均用Icancel表示，以体现两者的电流大小相同，图中，第一直流电流源、第二直流电流源以箭头不同表示方向不同。本实施例中，将第一直流电压源VSS作为第一直流电流源的供电电源，将第二直流电压源VDD作为第二直流电流源的供电电源；然并不以此为限，只要能够为第一直流电流源、第二直流电流源提供合适的供电电源即可；需要说明的是，第一直流电流源的电流大小以及方向确定后，就可以为其选择合适的供电电源；第二直流电流源亦是如此。
处理模块14用于控制第一切换开关K1、第二切换开关K2、第三切换开关K3、第四切换开关K4周期性地执行切换动作；如图6所示为本实施例中检测电路的时序波形示意图，图6中的Vo表示仪表放大器121的输出电压，AFF_Vout表示抗混叠滤波器122的输出电压，t0～t7表示不同时刻。
以下为对抵消电路124的电路原理的说明。
本发明电路方案中的抵消电路124的原理说明如下。
例如在t1～t2时刻，K1、K2、K3、K4均置于0端，此时检测电路可简化为如图7所示。
仪表放大器121的输出电压Vo满足：Vo-Vref＝V3-V4。
而V3＝V1+[(V1-V2)/Rg+Icancel]*Rf；
V4＝V2–[(V1-V2)/Rg+Icancel]*Rf；
故仪表放大器121的输出电压满足：Vo-Vref＝(V1-V2)*(2*Rf/Rg+1)+2*Icancel*Rf＝Voffset*(2*Rf/Rg+1)+2*Icancel*R f；
调节Icancel＝-Voffset*(2*Rf/Rg+1)/(2*Icancel)，即可使仪表放大器121的输出电压Vo满足：Vo-Vref＝0。
类似地，下一时刻，K1、K2、K3、K4均置于1端，当Icancel＝-Voffset*(2*Rf/Rg+1)/(2*Icancel)时，仪表放大器121的输出电压Vo仍然满足：Vo-Vref＝0。前后两次仪表放大器121的输出电压Vo均满足Vo-Vref＝0，故而起到抵消作用。
如果电桥传感器2的四个桥臂完全匹配，那么，在无外力作用于电桥传感器2的情况下，电桥传感器2的输出信号Voffset中的直流部分应当为零；但是由于加工工艺的原因，电桥传感器2中的四个桥臂往往无法做到完全匹配，那么，即使在无外力时，电桥传感器2的输出电压Voffset中的直流部分也不为零，称之为输出电压Voffset出现偏差，抵消电路124就是用于抵消电桥传感器2的输出电压Voffset的偏差。因此，在调试抵消电路124过程中，可以调试第一直流电流源、第二直流电流源的电流大小和方向，直到检测到的仪表放大器121的输出信号满足预设要求，该预设要求可以设定为，仪表放大器121的输出的电压大小与输入仪表放大器121的参考电压Vref的电压大小的差为零，其中参考电压Vref为模数转换模块13提供的共模电压。
本实施例的信号调理模块12中新增抵消电路124，可以尽可能抵消电桥传感器2中由于各桥臂不完全匹配导致的信号偏移问题；从而可以降低对电桥传感器中桥臂匹配度的要求，对于已有的电桥传感器，都能实现高质量的检测。
需要说明的是，本实施例中提供的抵消电路的具体实现方式仅是一个例子，任何等同变形并能达成抵消电路的目的的电路形式，均属于本申请实施例 所要保护的范围。另外，第四实施例也可以是在第一或第二实施例基础上进行的改进。
本申请第五实施例涉及一种芯片，包括上述第一至第四中任一实施例所述的电桥传感器的检测电路。
本申请第六实施例涉及一种检测***，包括电桥传感器以及上述第一至第四中任一实施例所述的电桥传感器的检测电路。
本领域的普通技术人员可以理解，上述各实施例是实现本申请的具体实施例，而在实际应用中，可以在形式上和细节上对其作各种改变，而不偏离本申请的精神和范围。

Claims (14)

  1. 一种电桥传感器的检测电路，其特征在于，包括：交流激励模块以及依次连接的信号调理模块、模数转换模块、处理模块；
    所述交流激励模块用于向所述电桥传感器施加交流激励信号；
    所述信号调理模块、所述模数转换模块用于对所述电桥传感器的输出信号依次进行处理；
    所述处理模块用于对处理后的所述输出信号进行解调，并根据解调后的所述输出信号得到所述电桥传感器的检测信息。
  2. 如权利要求1所述的电桥传感器的检测电路，其特征在于，所述处理模块基于相关双采样技术对解调后的所述输出信号进行处理，得到所述电桥传感器的检测信息。
  3. 如权利要求1或2所述的电桥传感器的检测电路，其特征在于，所述交流激励模块包括第一直流电压源、第二直流电压源以及用于将所述第一直流电压源、所述第二直流电压源切换连接至所述电桥传感器的第一激励施加端的第一切换开关；所述处理模块用于控制所述第一切换开关执行切换动作；所述第一直流电压源和所述第二直流电压源输出的电压不相同。
  4. 如权利要求3所述的电桥传感器的检测电路，其特征在于，所述交流激励模块还包括用于将所述第一直流电压源、所述第二直流电压源切换连接至所述电桥传感器的第二激励施加端的第二切换开关；所述处理模块用于控制所述第二切换开关执行切换动作；
    在第一状态中，所述处理模块控制所述第一直流电压源通过所述第一切换开关连接至所述第一激励施加端，且控制所述第二直流电压源通过所述第二切换开关连接至所述第二激励施加端；
    在第二状态中，所述处理模块控制所述第二直流电压源通过所述第一切换开关连接至所述第一激励施加端，且控制所述第一直流电压源通过所述第二切换开关连接至所述第二激励施加端。
  5. 如权利要求4所述的电桥传感器的检测电路，其特征在于，所述第一直流电压源和所述第二直流电压源输出的电压大小相同且方向相反。
  6. 如权利要求1至5中任一项所述的电桥传感器的检测电路，其特征在于，所述交流激励信号为方波信号。
  7. 如权利要求1至5中任一项所述的电桥传感器的检测电路，其特征在于，所述信号调理模块包括仪表放大器和抗混叠滤波器；
    所述仪表放大器的第一输入端连接于所述电桥传感器的输出端，所述仪表放大器的输出端连接于所述抗混叠滤波器的输入端，所述抗混叠滤波器的输出端连接于所述模数转换模块的输入端。
  8. 如权利要求7所述的电桥传感器的检测电路，其特征在于，所述信号调理模块还包括抵消电路；
    所述抵消电路连接于所述仪表放大器的第二输入端，且所述抵消电路被配置为：在无外力作用于所述电桥传感器的情况下，所述仪表放大器输出的电压大小满足预设要求。
  9. 如权利要求8所述的电桥传感器的检测电路，其特征在于，所述预设要求包括：所述仪表放大器输出的电压大小与输入所述仪表放大器的参考电压的电压大小的差为零，所述参考电压为所述模数转换模块提供的共模电压。
  10. 如权利要求8所述的电桥传感器的检测电路，其特征在于，所述仪表放大器具有两个所述第二输入端；
    所述抵消电路包括第一直流电流源、第二直流电流源、用于将所述第一直流电流源、所述第二直流电流源切换连接至其中一个所述第二输入端的第三切换开关、以及用于将所述第一直流电流源、所述第二直流电流源切换连接至另一个所述第二输入端的第四切换开关；所述处理模块用于控制所述第三切换开关、所述第四切换开关执行切换动作；所述第一直流电流源、所述第二直流电流源输出的电流大小相同且方向相反。
  11. 如权利要求10所述的电桥传感器的检测电路，其特征在于，所述仪表放大器包括第一运算放大器、第二运算放大器以及第三运算放大器；
    所述第一运算放大器的输出端连接于所述第三运算放大器的正相输入端，所述第二运算放大器的输出端连接于所述第三运算放大器的反相输入端；
    所述第一运算放大器的正相输入端和所述第二运算放大器的正相输入端作为所述仪表放大器的两个所述第一输入端；所述第一运算放大器的反相输入端和所述第二运算放大器的反相输入端作为所述仪表放大器的两个所述第二输入端；所述第三运算放大器作为所述仪表放大器的输出端。
  12. 如权利要求1所述的电桥传感器的检测电路，其特征在于，所述处理模块用于基于正交解调技术对处理后的所述输出信号进行解调。
  13. 一种芯片，其特征在于，包括：如权利要求1至12中任一项所述的电桥传感器的检测电路。
  14. 一种检测***，其特征在于，包括：电桥传感器以及如权利要求1至12中任一项所述的电桥传感器的检测电路。
PCT/CN2019/099316 2019-08-05 2019-08-05 电桥传感器的检测电路、芯片及检测*** WO2021022459A1 (zh)

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