CN219718187U - Weak signal amplifier using sensor - Google Patents
Weak signal amplifier using sensor Download PDFInfo
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- CN219718187U CN219718187U CN202320321860.XU CN202320321860U CN219718187U CN 219718187 U CN219718187 U CN 219718187U CN 202320321860 U CN202320321860 U CN 202320321860U CN 219718187 U CN219718187 U CN 219718187U
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Abstract
The utility model discloses a weak signal amplifier using a sensor. The device comprises an instrument amplifier, a filtering amplifying circuit and a V/A converting circuit, wherein the instrument amplifier is connected with signals input by a sensor through a voltage following circuit, the instrument amplifier is also connected with a zeroing circuit, the signal output end of the instrument amplifier is connected with the filtering amplifying circuit, and the filtering amplifying circuit is connected with the V/A converting circuit. The utility model mainly sets a voltage follower circuit at the joint of the instrument amplifier and the sensor, which is used for improving the input impedance of the system by the voltage follower circuit, ensuring that the signals output by the sensor are all acted on the instrument amplifier at the later stage, and simultaneously, a zeroing circuit is used for adjusting the zero point output by the instrument amplifier, ensuring that the output voltage is zero when the sensor does not act, and a filtering amplifying circuit is used for further filtering interference signals mixed in the signals, thereby improving the amplifying precision of the system, and realizing the high-precision processing of the weak signals of the sensor.
Description
Technical Field
The utility model relates to the technical field of signal processing devices, in particular to a weak signal amplifier using a sensor.
Background
As is well known, a sensor is a device mainly composed of sensitive components, and is a detection device capable of sensing measured information, converting the sensed information into an electric signal or other information output in a required form according to a certain rule so as to meet the requirements of information transmission, processing, storage, display, recording, control and the like. With the continuous development of microelectronic technology, sensor technology and integrated circuit technology, the detection precision of various types of sensors is obviously improved, and a signal processing circuit becomes a bottleneck for limiting the measurement precision of the sensors.
At present, the existing signal processing circuit mainly consists of an amplifier and a peripheral circuit, but the existing signal processing circuit has the defects of poor precision, difficult zero point adjustment and the like when aiming at weak signal processing, and cannot meet the requirements of a high-precision sensor measurement system. The method is characterized in that when the output signal of the sensor enters the amplifier, signal loss is easy to cause, so that the signal is problematic when the signal is not amplified and filtered, and zero drift is easy to cause to the amplifier along with the change of the environment such as voltage, temperature and the like, so that when the input signal is zero, the output signal of the circuit is not zero, and a false signal is formed, and the accuracy of the signal is influenced.
Disclosure of Invention
In view of the foregoing deficiencies in the prior art, an object of the present utility model is to provide a weak signal amplifier employing a sensor.
In order to achieve the above purpose, the present utility model adopts the following technical scheme:
the weak signal amplifier using the sensor comprises an instrument amplifier, a filtering amplifying circuit and a V/A converting circuit, wherein the instrument amplifier is connected with a signal input by the sensor through a voltage follower circuit, the instrument amplifier is also connected with a zeroing circuit, the signal output end of the instrument amplifier is connected with the filtering amplifying circuit, and the filtering amplifying circuit is connected with the V/A converting circuit;
the voltage follower circuit comprises a first operational amplifier and a second operational amplifier, the in-phase end of the first operational amplifier is connected with a negative electrode signal of the sensor through a first resistor, the in-phase end of the first operational amplifier is grounded through a second capacitor and connected with the in-phase end of the second operational amplifier through the first capacitor, the opposite-phase end of the first operational amplifier is connected with the output end of the first operational amplifier through a second resistor, the output ends of the first operational amplifier and the second operational amplifier are respectively connected with the signal input end of the instrument amplifier, the in-phase end of the second operational amplifier is connected with a positive electrode signal of the sensor through a third resistor, the in-phase end of the second operational amplifier is grounded through a third capacitor, and the opposite-phase end of the second operational amplifier is connected with the output end of the second operational amplifier through a fourth resistor.
Preferably, the zeroing circuit comprises a third operational amplifier, a fourth operational amplifier and a sliding rheostat, wherein the output end of the third operational amplifier is connected with the instrument amplifier, the in-phase end of the third operational amplifier is connected with the sliding end of the sliding rheostat, one fixed end of the sliding rheostat is connected with a 5V power supply through a fifth resistor and a sixth resistor which are sequentially connected in series, the other fixed end of the sliding rheostat is connected with the output end of the fourth operational amplifier through a tenth resistor, the inverting end of the fourth operational amplifier is connected with the 5V power supply through a seventh resistor and is connected with the output end of the fourth operational amplifier through a seventh resistor, and the in-phase end of the fourth operational amplifier is grounded through an eighth resistor.
Preferably, the filtering amplifying circuit comprises a fifth operational amplifier, wherein the in-phase end of the fifth operational amplifier is connected with the signal output end of the instrument amplifier through a fourth capacitor and an eleventh resistor which are sequentially connected in series and is grounded through a twelfth resistor, the fourth capacitor and the eleventh resistor are grounded through the fifth capacitor, and the output end of the fifth operational amplifier is connected with the V/A converting circuit and is connected between the eleventh resistor and the fourth capacitor through a thirteenth resistor.
Preferably, the V/a conversion circuit includes a sixth operational amplifier and a triode, the in-phase end of the sixth operational amplifier is connected with the filtering amplification circuit through a fourteenth resistor, the output end of the sixth operational amplifier is connected with the base electrode of the triode, the inverting end of the sixth operational amplifier is grounded through an eighteenth resistor and connected with the emitter electrode of the triode through a seventeenth resistor, the emitter electrode of the triode outputs a signal through a sixteenth resistor, and the in-phase end of the sixth operational amplifier is connected with the sixteenth resistor through a fifteenth resistor.
By adopting the scheme, the voltage follower circuit is mainly arranged at the joint of the instrument amplifier and the sensor, so that the voltage follower circuit is used for improving the input impedance of the system, signals output by the sensor are ensured to be all acted on the instrument amplifier at the later stage, meanwhile, the zero setting circuit is used for adjusting the zero point output by the instrument amplifier, the output voltage is ensured to be zero when the sensor does not act, and the filtering amplifier circuit is used for further filtering interference signals mixed in the signals to improve the amplification precision of the system, so that the high-precision processing of weak signals of the sensor can be realized.
Drawings
Fig. 1 is a schematic diagram of the structural principle of an embodiment of the present utility model.
Fig. 2 is a schematic circuit diagram of a voltage follower circuit according to an embodiment of the present utility model.
Fig. 3 is a schematic circuit diagram of a zeroing circuit according to an embodiment of the utility model.
Fig. 4 is a schematic diagram of the peripheral circuit structure of the instrumentation amplifier according to the embodiment of the present utility model.
Fig. 5 is a schematic circuit diagram of a filter amplifier circuit according to an embodiment of the utility model.
Fig. 6 is a schematic circuit diagram of a V/a conversion circuit according to an embodiment of the present utility model.
Description of the embodiments
The present utility model will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present utility model more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.
In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features. In the description of the present utility model, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
In the description of the present utility model, it should be noted that the terms "mounted," "connected," and "coupled" are to be construed broadly, as well as, for example, fixedly coupled, detachably coupled, or integrally coupled, unless otherwise specifically indicated and defined. Either mechanically or electrically. Can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.
As shown in fig. 1 to 6, the weak signal amplifier using a sensor provided in this embodiment includes an instrumentation amplifier (an AD620 amplifier may be used), a filtering amplifying circuit and a V/a conversion circuit, where the instrumentation amplifier is connected to a signal input by the sensor through a voltage follower circuit, the instrumentation amplifier is further connected to a zeroing circuit, and a signal output end of the instrumentation amplifier is connected to the filtering amplifying circuit, and the filtering amplifying circuit is connected to the V/a conversion circuit.
The embodiment mainly depends on the voltage follower circuit to improve the input impedance of the system, ensure that signals output by the sensor are all acted on the instrument amplifier at the later stage, and meanwhile, the zeroing circuit is used for adjusting the zero point output by the instrument amplifier, ensure that when the sensor does not act, the output voltage is zero, and the filtering amplifying circuit further filters interference signals mixed in the signals to improve the amplifying precision of the system, and the V/A converting circuit converts the output signals of the sensor into 4-20mA current signals for other instruments.
The circuit structure of the voltage follower circuit in this embodiment may adopt a circuit structure as shown in fig. 2, that is, the circuit structure includes a first operational amplifier A1 and a second operational amplifier A2, the in-phase end of the first operational amplifier A1 is connected to the negative electrode signal of the sensor through a first resistor R1, the in-phase end of the first operational amplifier A1 is further grounded through a second capacitor C2 and connected to the in-phase end of the second operational amplifier A2 through the first capacitor C1, the inverting end of the first operational amplifier A1 is connected to the output end of the first operational amplifier A2 through a second resistor R2, the output ends of the first operational amplifier A1 and the second operational amplifier A2 are respectively connected to the signal input end of the instrumentation amplifier, the in-phase end of the second operational amplifier A2 is connected to the positive electrode signal of the sensor through a third resistor R3, the in-phase end of the second operational amplifier A2 is further grounded through a third capacitor C3, and the inverting end of the second operational amplifier A2 is connected to the output end of the second operational amplifier A2 through a fourth resistor R4. The circuit mainly carries out voltage following in 2 signal lines output by the sensor, mainly depends on extremely low offset voltage and temperature drift of a first operational amplifier A1 and a second operational amplifier A2 (model is OPA 2277), and is very suitable for a weak signal amplifying circuit. The first resistor R1, the second capacitor C2, the third resistor R3 and the third capacitor C3 together form a first-order RC filter amplifying circuit which is used for filtering interference signals in sensor output signals, and the final signals are amplified by the first operational amplifier A1 and the second operational amplifier A2 and then input into the instrument amplifier.
Further, when the sensor does not act, noise signals are mixed in signals output by the sensor, the voltage value output after passing through the instrument amplifier is not zero, so that a zero-setting circuit is introduced into the circuit to adjust the zero point output by the amplifier, when the sensor does not act, the output voltage of the amplifier is 0, and the specific structure of the zero-setting circuit is shown as fig. 3, namely, the circuit comprises a third operational amplifier A3, a fourth operational amplifier A4 and a sliding rheostat Rb, the output end of the third operational amplifier A3 is connected with the instrument amplifier, the non-inverting end of the third operational amplifier A3 is connected with the sliding end of the sliding rheostat Rb, one fixed end of the sliding rheostat Rb is connected with a 5V power supply through a fifth resistor R5 and a sixth resistor R6 which are sequentially connected in series, the other fixed end of the sliding rheostat Rb is connected with the output end of the fourth operational amplifier A4 through a seventh resistor R7, the inverting end of the fourth operational amplifier A4 is connected with the output end of the sliding rheostat Rb through a seventh resistor R7, and the non-inverting end of the fourth operational amplifier A4 is connected with the sliding end of the sliding rheostat Rb through the eighth resistor R8. The system adopts the two-channel precise operational amplifier, utilizes the 1 st channel of the third operational amplifier A3 as a reverse proportional amplifying circuit, such as the design of the fourth operational amplifier A4, and aims to change + V input by a forward end into-5V output by a reverse end, so that the voltage variation range of two ends of the slide rheostat Rb is between-5 and + V, and then the 2 nd channel of the third operational amplifier A3 is used as a voltage follower to feed back the voltage to the REF end of the instrument amplifier so as to adjust the zero point.
From the formula out1=g (AD + -AD - ) +ADJ (where OUT1 is the output voltage of the instrumentation amplifier; G is the amplification factor of the instrumentation amplifier; AD) + 、AD － And the ADJ is the regulating voltage of zero point offset).
It can be seen that, first, the amplification factor of the system is adjusted by adjusting the sliding resistor Rt (the sliding resistor in the peripheral circuit of the instrumentation amplifier in fig. 4), and then the output voltage ADJ of the zeroing circuit is adjusted by adjusting the sliding resistor Rb, so that the output voltage of the amplifier is finally 0 when the sensor is not operated.
Further, the filtering and amplifying circuit of the embodiment is an important component, and in order to effectively filter the interference signal in the output signal of the instrumentation amplifier, the interference signal in the signal needs to be filtered by using an active second-order low-pass filtering and amplifying circuit. The system sets the cut-off frequency of the low-pass filter amplifying circuit to 10 kHz and the amplifying gain to 1. The specific structure of the filter amplifier circuit of this embodiment is shown in fig. 5. The circuit comprises a fifth operational amplifier A5, wherein the non-inverting terminal of the fifth operational amplifier A5 is connected with the signal output terminal of the instrument amplifier through a fourth capacitor C4 and an eleventh resistor R11 which are sequentially connected in series and is grounded through a twelfth resistor R12, the fourth capacitor C4 and the eleventh resistor R11 are grounded through the fifth capacitor C5, and the output terminal of the fifth operational amplifier A5 is connected with a V/A conversion circuit and is connected between the eleventh resistor R11 and the fourth capacitor C4 through a thirteenth resistor R13.
Further, after the filtering and amplifying circuit, the voltage of 0-3.3V is converted into a current signal of 4-20mA for other instruments, so that the structure of the V/a converting circuit in this embodiment is shown in fig. 6, that is, the V/a converting circuit includes a sixth operational amplifier A6 and a triode Q1, the in-phase end of the sixth operational amplifier A6 is connected with the filtering and amplifying circuit through a fourteenth resistor R14, the output end of the sixth operational amplifier Q6 is connected with the base of the triode Q1, the inverting end of the sixth operational amplifier A6 is grounded through an eighteenth resistor R18 and connected with the emitter of the triode Q1 through a seventeenth resistor R17, the emitter of the triode Q1 outputs a signal through a sixteenth resistor R16, and the in-phase end of the sixth operational amplifier A6 is connected with the sixteenth resistor R16 through a fifteenth resistor R15.
The foregoing description is only of the preferred embodiments of the present utility model, and is not intended to limit the scope of the utility model, but rather is intended to cover any equivalents of the structures or equivalent processes disclosed herein or in the alternative, which may be employed directly or indirectly in other related arts.
Claims (4)
1. The utility model provides an application sensor's weak signal amplifier, includes instrument amplifier, filter amplification circuit and V/A conversion circuit, its characterized in that: the instrument amplifier is connected with a signal input by the sensor through the voltage follower circuit, the instrument amplifier is also connected with a zero setting circuit, the signal output end of the instrument amplifier is connected with the filtering amplifying circuit, and the filtering amplifying circuit is connected with the V/A conversion circuit;
the voltage follower circuit comprises a first operational amplifier and a second operational amplifier, the in-phase end of the first operational amplifier is connected with a negative electrode signal of the sensor through a first resistor, the in-phase end of the first operational amplifier is grounded through a second capacitor and connected with the in-phase end of the second operational amplifier through the first capacitor, the opposite-phase end of the first operational amplifier is connected with the output end of the first operational amplifier through a second resistor, the output ends of the first operational amplifier and the second operational amplifier are respectively connected with the signal input end of the instrument amplifier, the in-phase end of the second operational amplifier is connected with a positive electrode signal of the sensor through a third resistor, the in-phase end of the second operational amplifier is grounded through a third capacitor, and the opposite-phase end of the second operational amplifier is connected with the output end of the second operational amplifier through a fourth resistor.
2. A weak signal amplifier employing a sensor as defined in claim 1, wherein: the zero setting circuit comprises a third operational amplifier, a fourth operational amplifier and a sliding rheostat, wherein the output end of the third operational amplifier is connected with the instrument amplifier, the in-phase end of the third operational amplifier is connected with the sliding end of the sliding rheostat, one fixed end of the sliding rheostat is connected with a 5V power supply through a fifth resistor and a sixth resistor which are sequentially connected in series, the other fixed end of the sliding rheostat is connected with the output end of the fourth operational amplifier through a tenth resistor, the inverting end of the fourth operational amplifier is connected with the 5V power supply through a seventh resistor and is connected with the output end of the fourth operational amplifier through a seventh resistor, and the in-phase end of the fourth operational amplifier is grounded through an eighth resistor.
3. A weak signal amplifier employing a sensor as claimed in claim 2, wherein: the filtering amplifying circuit comprises a fifth operational amplifier, wherein the in-phase end of the fifth operational amplifier is connected with the signal output end of the instrument amplifier through a fourth capacitor and an eleventh resistor which are sequentially connected in series and is grounded through a twelfth resistor, the fourth capacitor and the eleventh resistor are grounded through the fifth capacitor, and the output end of the fifth operational amplifier is connected with the V/A converting circuit and is connected between the eleventh resistor and the fourth capacitor through a thirteenth resistor.
4. A weak signal amplifier employing a sensor as claimed in claim 3, wherein: the V/A conversion circuit comprises a sixth operational amplifier and a triode, wherein the in-phase end of the sixth operational amplifier is connected with the filtering amplification circuit through a fourteenth resistor, the output end of the sixth operational amplifier is connected with the base electrode of the triode, the inverting end of the sixth operational amplifier is grounded through an eighteenth resistor and is connected with the emitting electrode of the triode through a seventeenth resistor, the emitting electrode of the triode outputs a signal through a sixteenth resistor, and the in-phase end of the sixth operational amplifier is connected with the sixteenth resistor through a fifteenth resistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320321860.XU CN219718187U (en) | 2023-02-27 | 2023-02-27 | Weak signal amplifier using sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320321860.XU CN219718187U (en) | 2023-02-27 | 2023-02-27 | Weak signal amplifier using sensor |
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| Publication Number | Publication Date |
|---|---|
| CN219718187U true CN219718187U (en) | 2023-09-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202320321860.XU Active CN219718187U (en) | 2023-02-27 | 2023-02-27 | Weak signal amplifier using sensor |
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| CN (1) | CN219718187U (en) |
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- 2023-02-27 CN CN202320321860.XU patent/CN219718187U/en active Active
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