CN110061711B - Signal amplifying circuit and electronic device - Google Patents
Signal amplifying circuit and electronic device Download PDFInfo
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- CN110061711B CN110061711B CN201910471903.0A CN201910471903A CN110061711B CN 110061711 B CN110061711 B CN 110061711B CN 201910471903 A CN201910471903 A CN 201910471903A CN 110061711 B CN110061711 B CN 110061711B
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- 239000003990 capacitor Substances 0.000 claims description 30
- 238000006243 chemical reaction Methods 0.000 claims description 29
- 230000003321 amplification Effects 0.000 claims description 24
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 24
- 230000009466 transformation Effects 0.000 claims description 13
- 230000001629 suppression Effects 0.000 claims description 8
- 230000001052 transient effect Effects 0.000 claims description 8
- 238000001514 detection method Methods 0.000 claims description 6
- 238000010586 diagram Methods 0.000 description 6
- 238000005070 sampling Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000003139 buffering effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
- G01L19/08—Means for indicating or recording, e.g. for remote indication
- G01L19/083—Means for indicating or recording, e.g. for remote indication electrical
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/34—Muting amplifier when no signal is present or when only weak signals are present, or caused by the presence of noise signals, e.g. squelch systems
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M1/00—Analogue/digital conversion; Digital/analogue conversion
- H03M1/12—Analogue/digital converters
- H03M1/124—Sampling or signal conditioning arrangements specially adapted for A/D converters
- H03M1/1245—Details of sampling arrangements or methods
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- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Control Of Amplification And Gain Control (AREA)
- Measuring Fluid Pressure (AREA)
Abstract
A signal amplifying circuit comprising: the amplifying module is used for amplifying a sensing signal of an air pressure sensor and outputting a first amplified signal, wherein the amplifying module has a preset gain; the gain controllable module is electrically connected with the amplifying module and is used for amplifying the first amplified signal and outputting a second amplified signal; the control unit is electrically connected with the gain controllable module and is used for detecting the second amplified signal and comparing the second amplified signal with a preset signal value to generate a control signal; the gain controllable module is further used for performing gain adjustment according to the control signal. The invention also provides an electronic device. The signal amplifying circuit and the electronic device can amplify the signal of the air pressure sensor to a reasonable range, and signal distortion is reduced to the greatest extent.
Description
Technical Field
The present invention relates to the field of electronic technology, and in particular, to a signal amplifying circuit for amplifying a sensing signal of an air pressure sensor and an electronic device including the signal amplifying circuit.
Background
The air pressure sensor can generate a certain degree of electric signal output after sensing the measured information, the electric signal is weak and can be detected by the back-end circuit after being amplified by the amplifying circuit, but if the amplification factor is too large, the signal is easy to distort. The existing method generally adopts an Automatic Gain Control (AGC) circuit to realize self-gain adjustment amplification, but because the voltage of an electric signal output by an air pressure sensor is extremely small, the rated input voltage requirement of the AGC circuit can not be met, and the resonance curve of a controlled amplifying stage is easy to deform, so that the signal is distorted.
Disclosure of Invention
In view of the foregoing, it is desirable to provide a signal amplifying circuit and an electronic device that can amplify the signal of an air pressure sensor to a reasonable range and minimize signal distortion.
An embodiment of the present invention provides a signal amplifying circuit for amplifying a sensing signal of an air pressure sensor, including:
The amplifying module is used for amplifying a sensing signal of an air pressure sensor and outputting a first amplified signal, wherein the amplifying module has a preset gain;
The gain controllable module is electrically connected with the amplifying module and is used for amplifying the first amplified signal and outputting a second amplified signal; and
The control unit is electrically connected with the gain controllable module and is used for detecting the second amplified signal and comparing the second amplified signal with a preset signal value to generate a control signal;
the gain controllable module is further used for performing gain adjustment according to the control signal.
Preferably, the sensing signal of the air pressure sensor is an alternating current signal, the signal amplifying circuit further comprises a bias processing module electrically connected to the amplifying module, and the sensing signal of the air pressure sensor is output to the amplifying module after voltage bias processing is performed by the bias processing module.
Preferably, the bias processing module includes:
One end of the first capacitor is used for receiving a sensing signal of the air pressure sensor;
one end of the transient suppression diode is electrically connected to one end of the first capacitor, and the other end of the transient suppression diode is grounded;
One end of the first resistor is electrically connected with the other end of the first capacitor, and the other end of the first resistor is electrically connected with a power supply end; and
And one end of the second resistor is electrically connected to the common end of the first resistor and the first capacitor, and the other end of the second resistor is grounded.
Preferably, the amplifying module includes a first amplifying unit and a second amplifying unit, where the first amplifying unit is configured to amplify a first preset gain, and the second amplifying unit is configured to amplify a second preset gain, and the second preset gain is greater than the first preset gain.
Preferably, the first amplifying unit includes:
The positive input end of the first amplifier is used for receiving the sensing signal; and
The third resistor is electrically connected between the negative input end of the first amplifier and the output end of the first amplifier;
The second amplifying unit includes:
one end of the second capacitor is electrically connected with the output end of the first amplifier;
one end of the fourth resistor is electrically connected with the other end of the second capacitor;
The positive input end of the second amplifier is electrically connected with one end of a fifth resistor and one end of a sixth resistor, the negative input end of the second amplifier is electrically connected with the other end of the fourth resistor, the other end of the fifth resistor is connected with a power supply end, and the other end of the sixth resistor is grounded; and
And the seventh resistor is electrically connected between the negative input end of the second amplifier and the output end of the second amplifier.
Preferably, the gain controllable module includes:
One end of the third capacitor is electrically connected with the amplifying module;
an eighth resistor, one end of which is electrically connected to the other end of the third capacitor;
The positive input end of the third amplifier is electrically connected with the other end of the eighth resistor, the negative input end of the third amplifier is electrically connected with one end of the ninth resistor and one end of the tenth resistor, the other end of the ninth resistor is electrically connected with the other end of the eighth resistor, and the other end of the tenth resistor is grounded;
The analog switch chip comprises first to eighth input ends, an output end and first to third control ends, wherein the output end of the analog switch chip is electrically connected with the output end of the third amplifier and the detection pin of the control unit, the first to third control ends of the analog switch chip are electrically connected with the control pin of the control unit, the first to eighth input ends of the analog switch chip are respectively electrically connected with one end of a feedback resistor, the other end of each feedback resistor is electrically connected with the positive input end of the third amplifier, and each feedback resistor has different resistance values.
Preferably, the signal amplifying circuit further includes a level conversion module electrically connected to the control pin of the control unit and the first to third control ends of the analog switch chip, where the level conversion module is configured to perform level conversion on the control signal output by the control pin, so as to convert the control signal of the first level output by the control pin into the control signal of the second level to the first to third control ends of the analog switch chip, where the second level is greater than the first level.
Preferably, the signal amplifying circuit further includes an analog-to-digital conversion module, an input end of the analog-to-digital conversion module is electrically connected to an output end of the analog switch chip and an output end of the third amplifier, an output end of the analog-to-digital conversion module is electrically connected to a detection pin of the control unit, and the analog-to-digital conversion module is configured to perform analog-to-digital conversion on a level signal of the output end of the third amplifier, so as to output a digital signal to the detection pin of the control unit.
Preferably, the signal amplifying circuit further comprises an impedance transformation module and a voltage division module which are electrically connected with the gain controllable module; the impedance transformation module comprises a voltage follower and is used for performing impedance transformation processing on the second amplified signal output by the gain controllable module; the control unit is used for sampling the second amplified signal after the voltage division processing so as to detect the sensing signal of the air pressure sensor.
The embodiment of the invention also provides an electronic device which comprises the signal amplifying circuit.
Compared with the prior art, the signal amplifying circuit and the electronic device amplify the sensing signal of the air pressure sensor through the fixed gain amplifying module matched with the AGC amplifying module, so that the sensing signal is firstly amplified to a measuring range, then gain control is carried out, the fixed gain amplifying module can amplify the weak sensing signal to the measuring range of the AGC amplifying module, the input voltage of the AGC amplifying module meets the rated input voltage requirement, meanwhile, the gain of the AGC amplifying module is automatically adjusted through the control chip, the signal of the air pressure sensor is always in a reasonable amplitude range after amplification, and signal distortion is reduced to the greatest extent.
Drawings
Fig. 1 is a functional block diagram of an electronic device according to an embodiment of the present invention.
Fig. 2 is a functional block diagram of a signal amplifying circuit in another embodiment of the present invention.
Fig. 3A and 3B are circuit diagrams of a signal amplifying circuit according to an embodiment of the invention.
Fig. 4 is a circuit diagram of a level shift unit in an embodiment of the present invention.
Description of the main reference signs
Detailed Description
The invention will be further described in the following detailed description in conjunction with the above-described figures.
Referring to fig. 1, an electronic device 1 according to an embodiment of the invention is provided. The electronic device 1 includes a signal amplifying circuit 100 and an air pressure sensor 200. The signal amplification circuit 100 may be configured to amplify the sensing signal output by the air pressure sensor 200 to a reasonable amplitude range, so that the back-end circuit can read the sensing signal, and signal distortion can be reduced to the greatest extent.
In one embodiment, after the air pressure sensor 200 detects the pressure change, an electrical signal is generated and output, and the electrical signal has weak intensity and can be detected by the back-end circuit after being amplified by the amplifying circuit, but if the amplification factor is too large, nonlinear distortion of the signal is easily caused. The signal amplification circuit 100 can amplify the signal of the air pressure sensor 200 to a reasonable range, and can realize gain self-control.
The signal amplifying circuit 100 includes an amplifying module 10, a gain controllable module 20, and a control unit 30. When the air pressure sensor 200 senses the change of the air pressure, a sensing signal is generated and outputted, and the sensing signal is weak, and can be better detected by the back-end circuit after being amplified by the signal amplifying circuit 100.
The amplifying module 10 is configured to amplify the sensing signal output by the air pressure sensor 200 and output a first amplified signal, wherein the amplifying module 10 has a preset gain. The gain controllable module 20 is electrically connected to the amplifying module 10, and the gain controllable module 20 is configured to amplify the first amplified signal and output a second amplified signal. The control unit 30 is electrically connected to the gain controllable module 20, and the control unit 30 is configured to detect the second amplified signal and compare the second amplified signal with a preset signal value to generate a control signal. The gain controllable module 20 is further configured to perform gain adjustment according to the control signal, so that the output second amplified signal is in a preset amplitude range, and signal distortion is reduced to the greatest extent.
The signal amplifying circuit 100 amplifies the sensing signal output by the air pressure sensor 200 by a fixed multiple through the amplifying module 10, so that the voltage of the input signal of the gain controllable module 20 is within a reasonable range (within the measurement range of the gain controllable module 20), and then the gain of the gain controllable module 20 can be adjusted through the control unit 30 according to the difference of the signal sizes, so that the amplified signal is always within a reasonable amplitude range, signal distortion is reduced to the greatest extent, and the back-end circuit is convenient for sampling the sensing signal after the amplification.
In an embodiment, the control unit 30 may detect the signal magnitude of the input signal of the gain controllable module 20, so as to adjust the gain of the gain controllable module 20 according to different signal magnitudes, so that the amplified signal is always within a reasonable amplitude range. For example, the smaller signal is amplified by a larger multiple, and the larger signal is amplified by a smaller multiple, so that the amplified signal is always in a reasonable amplitude range.
Referring to fig. 2, the sensing signal output by the air pressure sensor 200 is an ac signal. The signal amplifying circuit 100 further includes a bias processing module 40 electrically connected to the amplifying module 10, and the sensing signal output by the air pressure sensor 200 is output to the amplifying module 10 for amplifying after being subjected to voltage bias processing by the bias processing module 40.
In one embodiment, the amplifying module 10 includes a first amplifying unit 102 and a second amplifying unit 104. The first amplifying unit 102 is configured to amplify the sensing signal by a first preset gain, the second amplifying unit 104 is electrically connected to the first amplifying unit 102, and the second amplifying unit 104 is configured to amplify the signal amplified by the first amplifying unit 102 by a second preset gain. The first preset gain and the second preset gain can be set according to actual use requirements. For example, the amplification factor of the first amplifying unit 102 is 5 times, the amplification factor of the second amplifying unit 104 is 15 times, and the second preset gain is larger than the first preset gain.
In an embodiment, the gain controllable module 20 includes a switching module 202 for switching the feedback resistance value, so as to adjust the gain of the gain controllable module 20 by changing the feedback resistance value of the gain controllable module 20.
In an embodiment, the switching module 202 may implement feedback resistance value switching through an analog switch chip. The control unit 30 may be a control chip, for example, the control unit 30 may be an MCU, a single-chip microcomputer, or the like. The signal amplifying circuit 100 may further include an analog-to-digital conversion module 50, a level conversion module 60, an impedance transformation module 70, and a voltage division module 80. The analog-to-digital conversion module 50 is electrically connected to the gain controllable module 20 and the control unit 30, and the analog-to-digital conversion module 50 is configured to convert the detected second amplified signal into a digital signal and input the digital signal to the control unit 30, so that the control unit 30 can compare the second amplified signal with a preset signal value to generate a control signal.
In one embodiment, since the pin level (typically 3.3V) of the control chip is inconsistent with the pin level (typically 5V) of the analog switch chip, the level conversion module 60 can implement control of the analog switch chip by outputting the control signal from the control chip. Specifically, the level conversion module 60 is electrically connected to the control unit 30 and the gain controllable module 20, and the level conversion module is configured to level convert a control signal output by the control chip to convert a control signal of a first level into a control signal of a second level to the analog switch chip of the gain controllable module 20, where the second level is preferably greater than the first level. For example, the level conversion module 60 converts the 3.3V control signal output by the control chip into a 5V control signal, so as to control the analog switch chip to gate.
The impedance transformation module 70 is electrically connected to the gain controllable module 20, and the impedance transformation module 70 includes a voltage follower for performing impedance transformation processing on the second amplified signal output by the gain controllable module, so as to implement impedance matching. The impedance transformation module 70 may perform buffering and isolation functions to reduce signal distortion.
In an embodiment, since the pin level (typically 3.3V) of the control chip is inconsistent with the pin level (typically 5V) of the amplifier in the gain controllable module 20, the voltage dividing module 80 can realize that the control chip normally samples the amplified sensing signal, and the sampling upper limit of the control chip is not exceeded. Specifically, the voltage dividing module 80 is electrically connected to the impedance transformation module 70, and the voltage dividing module 80 is configured to divide the second amplified signal output by the gain controllable module 20, so that the control chip can sample the divided second amplified signal to realize detecting the amplified sensing signal.
Referring to fig. 3A and 3B, a circuit diagram of a signal amplifying circuit 100 is provided according to an embodiment of the invention.
The air pressure sensor 200 may be configured to perform power supply and sensing signal transmission through an audio interface 202, for example, the air pressure sensor 200 may be connected to the signal amplifying circuit 100 through a 3.5mm audio interface.
The bias processing module 40 includes a transient suppression diode TVS1, first to third resistors R1 to R3, and a first capacitor C1. One end of the transient suppression diode TVS1 is used for receiving a sensing signal output by the air pressure sensor 200, and the other end of the transient suppression diode TVS1 is grounded. One end of the first resistor R1 is electrically connected to one end of the transient suppression diode TVS1, and the other end of the first resistor R1 is grounded. One end of the first capacitor C1 is electrically connected to one end of the first resistor R1, the other end of the first capacitor C1 is electrically connected to one end of the second resistor R2 and one end of the third resistor R3, the other end of the second resistor R2 is electrically connected to the first power supply end Vcc1, and the other end of the third resistor R3 is grounded. The voltage of the first power supply terminal Vcc1 can be set according to actual requirements. In other embodiments of the present invention, the first resistor R1 may be omitted.
The first amplifying unit 102 includes a first amplifier OP1, fourth to sixth resistors R4 to R6, a second capacitor C2, and a third capacitor C3. The positive input end of the first amplifier OP1 is electrically connected to one end of the third resistor R3, and the fourth resistor R4 is electrically connected between the negative input end and the output end of the first amplifier OP 1. One end of the second capacitor C2 is electrically connected to one end of the fourth resistor R4, the other end of the second capacitor C2 is electrically connected to one end of the fifth resistor R5, and the other end of the fifth resistor R5 is electrically connected to the other end of the fourth resistor R4. One end of the sixth resistor R6 is electrically connected to one end of the fourth resistor R4, the other end of the sixth resistor R6 is electrically connected to one end of the third capacitor C3, and the other end of the third capacitor C3 is grounded. In other embodiments of the present invention, some components of the first amplifying unit 102 may be omitted, such as the third capacitor C3 and the sixth resistor R6 may be omitted.
The second amplifying unit 104 includes a fourth capacitor C4, seventh to eleventh resistors R7 to R11, and a second amplifier OP2. The seventh resistor R7, the fourth capacitor C4, and the eighth resistor R8 are sequentially connected in series between the output terminal of the first amplifier OP1 and the negative input terminal of the second amplifier OP2. The ninth resistor R9 is electrically connected between the negative input terminal and the output terminal of the second amplifier OP2. The positive input end of the second amplifier OP2 is electrically connected to one end of the tenth resistor R10 and one end of the eleventh resistor R11, the other end of the tenth resistor R10 is electrically connected to the second power supply end Vcc2, and the other end of the eleventh resistor R11 is grounded. The voltage value of the second power supply terminal Vcc2 can be set according to actual requirements. In other embodiments of the present invention, some elements of the second amplifying unit 104 may be omitted, such as the seventh resistor R7 may be omitted or the eighth resistor R8 may be omitted.
The control unit 30 comprises an MCU. The gain controllable module 20 includes a fifth capacitor C5, a third amplifier OP3, twelfth to fifteenth resistors R12 to R15, an analog switch chip CD1, and first to eighth feedback resistors Rb1 to Rb8. The twelfth resistor R12, the fifth capacitor C5, and the thirteenth resistor R13 are sequentially connected in series between the output end of the second amplifier OP2 and the positive input end of the third amplifier OP 3. The fourteenth resistor R14 is electrically connected between the positive input terminal and the negative input terminal of the third amplifier OP3, one end of the fifteenth resistor R15 is electrically connected to the negative input terminal of the third amplifier OP3, and the other end of the fifteenth resistor R15 is grounded. The analog switch chip CD1 includes first to eighth access terminals CH1 to CH8, a common terminal COM, and first to third control terminals A1, B1, and C1. The first to eighth access terminals CH1 to CH8 are electrically connected to one ends of the first to eighth feedback resistors Rb1 to Rb8 in a one-to-one correspondence, and the other ends of the first to eighth feedback resistors Rb1 to Rb8 are electrically connected to the positive input terminal of the third amplifier OP 3. The common terminal COM is electrically connected to the output terminal of the third amplifier OP3, and the first to third control terminals A1, B1, C1 are electrically connected to the MCU to receive the control signal output by the MCU. In other embodiments of the present invention, some elements of the gain controllable module 20 may be omitted, such as the twelfth resistor R12 or the thirteenth resistor R13.
In an embodiment, the gain controllable module 20 may further include a digital potentiometer electrically connected between the positive input end and the output end of the third amplifier OP3, and the MCU is used to control the resistance value of the digital potentiometer, so as to realize the gain adjustability of the gain controllable module 20.
In an embodiment, the first to eighth feedback resistors Rb1 to Rb8 have different resistance values, i.e., the gain controllable module 20 may have eight different sets of gain steps. Eight groups of different feedback resistors are obtained by controlling different switch states of the analog switch chip CD1 through the MCU, so that the gain of the gain controllable module 20 can be adjusted.
In an embodiment, the common terminal COM is further electrically connected to the MCU, so that the MCU can detect the second amplified signal and compare the second amplified signal with a pre-stored preset signal value to generate a control signal. When the second amplified signal is detected to be greater than the preset signal value, a control signal for reducing the gain may be output, so that the gain controllable module 20 is switched to a smaller gain gear; when the second amplified signal is detected to be smaller than the preset signal value, a control signal for increasing the gain may be output, so that the gain controllable module 20 switches to a larger gain gear.
In an embodiment, the MCU is electrically connected to the common port COM through the analog-to-digital conversion module 50, the signal at the output end of the third amplifier OP3 is input to the MCU after being subjected to analog-to-digital conversion by the analog-to-digital conversion module 50, the MCU calculates an input digital signal, compares the calculation result with a preset signal value, and when detecting that the output value of the third amplifier OP3 is smaller than the preset signal value, can control the analog switch chip CD1 to gradually increase the gain, and when detecting that the output value of the third amplifier OP3 is greater than the preset signal value, can control the analog switch chip CD1 to gradually decrease the gain, so as to determine the gain that is optimally matched. The specific circuit structure of the analog-to-digital conversion module 50 may be a prior art analog-to-digital conversion unit, which is not limited herein.
In an embodiment, the MCU is further electrically connected to the first to third control terminals A1, B1, C1 through a level shift module 60. The level conversion module 60 may convert the 3.3V control signal output by the MCU into a 5V control signal, and further control the analog switch chip CD1 to switch between different switch states by using the 5V control signal. The level shift module 60 may include three level shift units 602, where each level shift unit 602 is electrically connected between a control pin of the MCU and a control terminal A1/B1/C1 of the analog switch chip CD 1. Fig. 4 illustrates a circuit diagram of one embodiment of a level shifting unit 602. The level shift unit 602 is provided with a fourth power supply terminal Vcc4, and performs level shift by two NPN transistors Q1, Q2 and a plurality of resistors.
In an embodiment, the first to third amplifiers OP1 to OP3 may employ high-precision operational amplifiers, such as LT1498CS8 chips. The analog switch chip CD1 may be a CD4051 chip.
In one embodiment, the impedance transformation module 70 includes a fourth amplifier OP4 and a sixteenth resistor R16. The negative input end of the fourth amplifier OP4 is electrically connected to the output end of the third amplifier OP3, and the output end of the fourth amplifier OP4 is electrically connected to the positive input end and the negative input end of the fourth amplifier OP 4. The sixteenth resistor R16 is electrically connected between the negative input terminal and the output terminal of the fourth amplifier OP 4.
In one embodiment, the voltage dividing module 80 includes seventeenth to twentieth resistors R17 to R20. One end of the seventeenth resistor R17 is electrically connected to the third power supply end Vcc3, the other end of the seventeenth resistor R17 is electrically connected to one end of the eighteenth resistor R18 and the output end of the fourth amplifier OP4, and the other end of the eighteenth resistor R18 is grounded. One end of the nineteenth resistor R19 is electrically connected to the output end of the fourth amplifier OP4, the other end of the nineteenth resistor R19 is electrically connected to one end of the twentieth resistor R20 and the MCU, and the other end of the twentieth resistor R20 is grounded. The MCU samples a signal at one end of the twentieth resistor R20 to detect the amplified sensing signal. The voltage of the third power supply terminal Vcc3 can be set according to actual requirements.
According to the signal amplifying circuit and the electronic device, the sensing signal of the air pressure sensor is amplified by the fixed-gain amplifying module matched with the AGC amplifying module, the sensing signal is amplified to the measuring range, then gain control is carried out, the fixed-gain amplifying module can amplify the weak sensing signal to the measuring range of the AGC amplifying module, the input voltage of the AGC amplifying module meets the rated input voltage requirement, meanwhile, the gain of the AGC amplifying module is automatically adjusted through the control chip, so that the signal of the air pressure sensor is always in a reasonable amplitude range after amplification, and signal distortion is reduced to the greatest extent.
Other corresponding changes and modifications will occur to those skilled in the art in light of the present teachings and the actual needs of the invention in connection with production, and such changes and modifications are intended to be within the scope of the present disclosure.
Claims (9)
1. A signal amplification circuit for amplifying a sensing signal of an air pressure sensor, the signal amplification circuit comprising:
the amplifying module is used for amplifying the sensing signal of the air pressure sensor and outputting a first amplified signal, wherein the amplifying module has a preset gain;
The gain controllable module is electrically connected with the amplifying module and is used for amplifying the first amplified signal and outputting a second amplified signal;
The control unit is electrically connected with the gain controllable module and is used for detecting the second amplified signal and comparing the second amplified signal with a preset signal value to generate a control signal;
the impedance transformation module is electrically connected between the gain controllable module and the control unit and is used for carrying out impedance transformation processing on the second amplified signal output by the gain controllable module;
The gain controllable module is further configured to perform gain adjustment according to the control signal, where the gain controllable module includes:
one end of the first capacitor is electrically connected with the amplifying module;
one end of the first resistor is electrically connected with the other end of the first capacitor;
the positive input end of the first amplifier is electrically connected with the other end of the first resistor, the negative input end of the first amplifier is electrically connected with one end of the second resistor and one end of the third resistor, the other end of the second resistor is electrically connected with the other end of the first resistor, and the other end of the third resistor is grounded;
the analog switch chip comprises first to eighth input ends, an output end and first to third control ends, wherein the output end of the analog switch chip is electrically connected with the output end of the first amplifier and the detection pin of the control unit, the first to third control ends of the analog switch chip are electrically connected with the control pin of the control unit, the first to eighth input ends of the analog switch chip are respectively electrically connected with one end of a feedback resistor, the other end of each feedback resistor is electrically connected with the positive input end of the first amplifier, and each feedback resistor has different resistance values.
2. The signal amplification circuit of claim 1, wherein the sensing signal of the air pressure sensor is an ac signal, the signal amplification circuit further comprises a bias processing module electrically connected to the amplifying module, and the sensing signal of the air pressure sensor is output to the amplifying module after being subjected to voltage bias processing by the bias processing module.
3. The signal amplification circuit of claim 2, wherein the bias processing module comprises:
One end of the second capacitor is used for receiving a sensing signal of the air pressure sensor;
One end of the transient suppression diode is electrically connected to one end of the second capacitor, and the other end of the transient suppression diode is grounded;
one end of the fourth resistor is electrically connected with the other end of the second capacitor, and the other end of the fourth resistor is electrically connected with a power supply end; and
And one end of the fifth resistor is electrically connected to the common end of the fourth resistor and the second capacitor, and the other end of the fifth resistor is grounded.
4. The signal amplification circuit of claim 2, wherein the amplification module comprises a first amplification unit for amplifying a first preset gain and a second amplification unit for amplifying a second preset gain, the second preset gain being greater than the first preset gain.
5. The signal amplification circuit of claim 4, wherein the first amplification unit comprises:
the positive input end of the second amplifier is used for receiving the sensing signal; and
A sixth resistor electrically connected between the negative input terminal of the second amplifier and the output terminal of the second amplifier;
The second amplifying unit includes:
One end of the third capacitor is electrically connected with the output end of the second amplifier;
a seventh resistor, one end of which is electrically connected to the other end of the third capacitor;
The positive input end of the third amplifier is electrically connected with one end of an eighth resistor and one end of a ninth resistor, the negative input end of the third amplifier is electrically connected with the other end of the seventh resistor, the other end of the eighth resistor is connected with a power supply end, and the other end of the ninth resistor is grounded; and
And the tenth resistor is electrically connected between the negative input end of the third amplifier and the output end of the third amplifier.
6. The signal amplification circuit of claim 1, further comprising a level conversion module electrically connected to a control pin of the control unit and first to third control terminals of the analog switch chip, wherein the level conversion module is configured to level convert a control signal output by the control pin to a control signal of a second level to the first to third control terminals of the analog switch chip, and the second level is greater than the first level.
7. The signal amplification circuit of claim 1, further comprising an analog-to-digital conversion module, wherein an input end of the analog-to-digital conversion module is electrically connected to an output end of the analog switch chip and an output end of the first amplifier, an output end of the analog-to-digital conversion module is electrically connected to a detection pin of the control unit, and the analog-to-digital conversion module is configured to perform analog-to-digital conversion on a level signal of the output end of the first amplifier to output a digital signal to the detection pin of the control unit.
8. The signal amplification circuit of claim 1, further comprising a voltage division module electrically connected between the impedance transformation module and the control unit, the voltage division module configured to divide the second amplified signal output by the gain controllable module, and the control unit further configured to sample the divided second amplified signal to detect the sensing signal of the air pressure sensor.
9. An electronic device comprising the signal amplifying circuit according to any one of claims 1 to 8.
Priority Applications (1)
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