CN213846617U - Low-noise differential amplification filter circuit for high-precision weak signals - Google Patents
Low-noise differential amplification filter circuit for high-precision weak signals Download PDFInfo
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- CN213846617U CN213846617U CN202023153499.XU CN202023153499U CN213846617U CN 213846617 U CN213846617 U CN 213846617U CN 202023153499 U CN202023153499 U CN 202023153499U CN 213846617 U CN213846617 U CN 213846617U
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Abstract
The utility model provides a low noise difference amplification filter circuit of weak signal of high accuracy, include: the device comprises an alternating current differential amplifying circuit and a band-pass filter circuit, wherein the input end of the alternating current differential amplifying circuit is connected with an alternating current voltage signal responded by a battery; the input end of the band-pass filter circuit is connected with the output end of the alternating current differential amplification circuit; the output end of the band-pass filter circuit is connected with the battery internal resistance tester so as to transmit the amplified alternating voltage signal subjected to interference filtering to the battery internal resistance tester for calculation and application. The utility model discloses to faint small-signal, the amplification function has higher precision to provide good filtering performance, thereby guaranteed the stability of circuit work.
Description
Technical Field
The utility model relates to a battery internal resistance measures technical field, in particular to low noise difference amplification filter circuit of weak signal of high accuracy.
Background
The common method for realizing the on-line measurement of the internal resistance of the battery is an alternating current injection method, namely, an alternating current signal is injected into the battery through a signal source, alternating voltage signals generated at two ends of the battery and input current are measured, and then the internal resistance of the battery can be calculated. Because the internal resistance of the battery is millivolt level, the voltage signal generated by injecting the alternating current signal is a weak small signal. For each weak measurand, the amplitude is amplified by an amplifier to reflect the measured size. However, because the measured signal is very weak, the noise inherent in the amplifying circuit and the measuring circuit and the external interference are often much larger than the amplitude of the useful signal, and meanwhile, the process of amplifying the measured signal also amplifies the noise and inevitably adds some extra noise, so that the useful signal can be extracted only by increasing the amplitude of the weak signal under the condition of effectively suppressing the noise.
SUMMERY OF THE UTILITY MODEL
The purpose of the present invention is to solve at least one of the technical drawbacks.
Therefore, the utility model aims to provide a low noise difference amplification filter circuit of weak signal of high accuracy.
In order to achieve the above object, an embodiment of the present invention provides a low-noise differential amplification filter circuit for high-precision weak signals, including: the input end of the alternating current differential amplifying circuit is connected with an alternating current voltage signal responded by a battery so as to amplify the connected alternating current voltage signal; the alternating current differential amplifying circuit includes: the negative input end of the alternating current differential amplification circuit is connected with a positive electrode signal of an alternating voltage signal through a resistor and a capacitor, the positive input end of the alternating current differential amplification circuit is connected with a negative electrode signal of the alternating voltage signal through a resistor and a capacitor, the external gain resistor connecting end of the integrated operational amplifier is connected with the amplification factor selection circuit, and the output end of the integrated operational amplifier is connected with the input end of the band-pass filter circuit; the input end of the band-pass filter circuit is connected with the output end of the alternating current differential amplification circuit so as to filter interference signals of the amplified alternating current voltage signals; the band-pass filter circuit adopts multiple feedback type 2 nd order band-pass filter, multiple feedback type 2 nd order band-pass filter includes: the multi-feedback type 2-order low-pass filter circuit and the voltage follower circuit at the front stage and the multi-feedback type 2-order high-pass filter circuit and the voltage follower circuit at the rear stage; the front stage and the rear stage are cascaded to form the multiple feedback type 2-order band-pass filter; and the output end of the band-pass filter circuit is connected with the battery internal resistance tester so as to transmit the amplified alternating voltage signal subjected to interference filtering to the battery internal resistance tester.
Further, the amplification factor selection circuit selects different access resistors through switch switching to set corresponding amplification factors.
Furthermore, the amplification factor selection circuit adopts a differential multi-channel digital control analog switch, and the analog switch is utilized to realize the gating of the external gain resistor.
Further, the multi-feedback 2-order low-pass filter circuit and the voltage follower circuit at the previous stage comprise: the negative input end of the first operational amplifier is connected with the output end of the alternating current differential amplification circuit through a resistor, and the positive input end of the first operational amplifier is grounded through a resistor; the output end of the first operational amplifier is connected with the positive input end of the second operational amplifier, and the negative input end and the output end of the second operational amplifier are in short circuit.
Further, the multi-feedback 2-order high-pass filter circuit and the voltage follower circuit of the post-stage include: the negative input end of the third operational amplifier is connected with the output end of the second operational amplifier through a resistor and a capacitor, the positive input end of the third operational amplifier is grounded through a resistor, the positive input end of the fourth operational amplifier is connected with the output end of the third operational amplifier, the negative input end of the fourth operational amplifier is in short circuit with the output end, and the output end of the fourth operational amplifier is connected with the battery internal resistance tester.
According to the utility model discloses low noise difference amplification filter circuit of high accuracy weak signal is to the weak signal detection circuitry of battery internal resistance, integrated analysis circuit noise, signal bandwidth and circuit stability, a low noise difference amplification filter circuit who designs on this basis to give circuit parameter selection method. Compare with ordinary single-ended amplifier, the utility model discloses can effectively restrain the unsteady interference of common mode interference and ground wire voltage in the input signal, to weak small-signal, the enlarged function of this circuit has higher precision to provide good filtering performance, thereby guaranteed the stability of circuit work.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic diagram of measuring internal resistance of a battery according to an embodiment of the present invention;
fig. 2 is a structural diagram of a low-noise differential amplification filter circuit for high-precision weak signals according to an embodiment of the present invention;
fig. 3 is a schematic diagram of an ac differential amplifier circuit according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a magnification selection circuit according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a bandpass filter circuit according to an embodiment of the present invention;
fig. 6 is a schematic diagram of a multiple feedback 2-order bandpass filter circuit according to an embodiment of the present invention;
fig. 7 is a waveform diagram of the input and output of the differential amplifier circuit according to the embodiment of the present invention;
fig. 8 is an interface diagram of waveform display parameters according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present invention, and should not be construed as limiting the present invention.
Before introducing the utility model discloses, at first explain the measuring method of battery internal resistance:
the alternating current injection measurement method of the internal resistance of the battery is a well-known effective method and has the characteristics of high measurement precision and low power consumption. The measurement principle is as shown in fig. 1, a low-frequency alternating current signal I is injected into the battery by an excitation source, the battery generates a response voltage signal, and the internal resistance of the battery can be calculated by sampling the response alternating voltage V generated by the battery.
Because the internal resistance of the battery is millivolt, the response alternating voltage signal on the battery is a weak small signal, so that the pre-amplification filtering is required to be firstly carried out and then input into a relevant tester. The utility model provides a low noise difference amplifies filter circuit is exactly the design that carries out preamplification filter circuit, mainly comprises interchange difference amplification and band pass filter.
As shown in fig. 2, the utility model discloses a low noise difference amplification filter circuit 100 of weak signal of high accuracy, include: an alternating current differential amplifying circuit 1 and a band-pass filter circuit 2.
Specifically, the input end of the alternating current differential amplification circuit 1 is connected to an alternating current voltage signal 3 responded by the battery and used for amplifying the connected alternating current voltage signal; the input end of the band-pass filter circuit 2 is connected with the output end of the alternating current differential amplification circuit 1 and is used for filtering and processing interference signals of the amplified alternating current voltage signals; the output end of the band-pass filter circuit 2 is connected with the battery internal resistance tester 4 so as to transmit the amplified alternating voltage signal after interference filtering to the battery internal resistance tester 4 for calculation and application.
As shown in fig. 3, the ac differential amplifier circuit 1 includes: the device comprises an integrated operational amplifier and an amplification factor selection circuit, wherein a negative input end of an alternating current differential amplification circuit 1 is connected with a positive signal of an alternating current voltage signal through a resistor and a capacitor, a positive input end of the alternating current differential amplification circuit 1 is connected with a negative signal of the alternating current voltage signal through a resistor and a capacitor, an external gain resistor connecting end of the integrated operational amplifier is connected with the amplification factor selection circuit, and an output end of the integrated operational amplifier is connected with an input end of a band-pass filter circuit 2.
In the embodiment of the utility model, integrated operational amplifier can choose integrated fortune to put AD620 as the main part and realize the difference and amplify the function for use. The AD620 is a low-cost and high-precision instrument amplifier, the performance is stable, the gain is adjustable, the gain range G is 1 to 10000, the amplification factor is determined by an external gain control resistor RG between a pin 1 and a pin 8, and the gain equation is G ═ 1+ (49.4K/RG).
The present invention is directed to a circuit for amplifying a RG signal.
Specifically, the amplification factor selection circuit switches and selects different access resistors through a switch to set corresponding amplification factors.
As shown in fig. 4, the amplification factor selection circuit uses a differential multi-channel digital control analog switch, and uses the analog switch to realize the gating of the external gain resistor.
Preferably, the amplification factor selection circuit can adopt a differential 4-channel digital control analog switch with the model number of CD 4052. In the circuit, the gating function of an external gain resistor is designed by using an analog switch, and switching of different amplification factors can be realized, as shown in fig. 4, an RG resistor in fig. 3 is replaced by an amplification factor selection circuit, and the circuit can select reasonable amplification factors for weak signals in different ranges, so that the signals are in an optimal acquisition voltage range. For example, referring to fig. 4, the differential 4-channel digitally controlled analog switch can be selectively connected to R53, R54, R55 or R56, and by connecting resistors with different resistances, the design of the amplification factor can be realized.
As shown in fig. 5 and 6, the band pass filter circuit 2 employs a multiple feedback type 2-order band pass filter.
Specifically, the multiple feedback type 2-order bandpass filter includes: the multi-feedback type 2-order low-pass filter circuit and the voltage follower circuit at the front stage and the multi-feedback type 2-order high-pass filter circuit and the voltage follower circuit at the rear stage; the front stage and the rear stage are cascaded to form a multiple feedback type 2-order band-pass filter.
The utility model discloses an in the embodiment, 2 order low pass filter circuit of multistage multiple feedback type and voltage follower circuit of front level, include: the negative input end of the first operational amplifier is connected with the output end of the alternating current differential amplification circuit 1 through a resistor, and the positive input end of the first operational amplifier is grounded through a resistor; the output end of the first operational amplifier is connected with the positive input end of the second operational amplifier, and the negative input end and the output end of the second operational amplifier are in short circuit.
The multistage 2 nd order high-pass filter circuit of feedback type and voltage follower circuit of poststage include: the negative input end of the third operational amplifier is connected with the output end of the second operational amplifier through a resistor and a capacitor, the positive input end of the third operational amplifier is grounded through a resistor, the positive input end of the fourth operational amplifier is connected with the output end of the third operational amplifier, the negative input end of the fourth operational amplifier is in short circuit with the output end, and the output end of the fourth operational amplifier is connected with the battery internal resistance tester 4.
Referring to fig. 5 and 6, after the signal is amplified, the high-frequency and low-frequency interference signals are filtered by a band-pass filter. The utility model provides a four-channel operational amplifier OP497 chip that first to fourth operational amplifier chose for use has the precision ability. The multi-feedback 2-order band-pass filter circuit 2BPF is formed by cascading a low-pass filter circuit LPF at the front stage and a high-pass filter circuit HPF at the rear stage, can detect band-pass signals of 0.36-3.6 kHz, and can effectively filter signal interference outside a band-pass band.
Right the utility model discloses a low noise difference amplification filter circuit 100 tests: the ac differential amplifier circuit 1 first performs an electronic circuit simulation test by multisim, during the test, the feedback resistor RG is selected to be 500, the amplification factor at this time is G99.8, the ac voltage signals at both ends of the battery pass through the differential amplifier and filter circuit, the input waveform and the output waveform are as shown in fig. 7, and the waveform display parameters are as shown in fig. 8.
In summary, with the low-noise differential amplification filter circuit 100 of the present invention, the dc signal can be effectively isolated and the noise interference can be eliminated through the ac differential amplification circuit 1; other interference signals than the signal frequency are effectively filtered by the band-pass filter circuit 2.
According to the utility model discloses low noise difference amplification filter circuit of high accuracy weak signal is to the weak signal detection circuitry of battery internal resistance, integrated analysis circuit noise, signal bandwidth and circuit stability, a low noise difference amplification filter circuit who designs on this basis to give circuit parameter selection method. Compare with ordinary single-ended amplifier, the utility model discloses can effectively restrain the unsteady interference of common mode interference and ground wire voltage in the input signal, to weak small-signal, the enlarged function of this circuit has higher precision to provide good filtering performance, thereby guaranteed the stability of circuit work.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Although embodiments of the present invention have been shown and described, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that changes, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art without departing from the principles and spirit of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (5)
1. A low-noise differential amplification filter circuit of a high-precision weak signal is characterized by comprising: an alternating current differential amplifying circuit and a band-pass filtering circuit, wherein,
the input end of the alternating current differential amplification circuit is connected with an alternating current voltage signal responded by the battery so as to amplify the connected alternating current voltage signal; the alternating current differential amplifying circuit includes: the negative input end of the alternating current differential amplification circuit is connected with a positive electrode signal of an alternating voltage signal through a resistor and a capacitor, the positive input end of the alternating current differential amplification circuit is connected with a negative electrode signal of the alternating voltage signal through a resistor and a capacitor, the external gain resistor connecting end of the integrated operational amplifier is connected with the amplification factor selection circuit, and the output end of the integrated operational amplifier is connected with the input end of the band-pass filter circuit;
the input end of the band-pass filter circuit is connected with the output end of the alternating current differential amplification circuit so as to filter interference signals of the amplified alternating current voltage signals; the band-pass filter circuit adopts multiple feedback type 2 nd order band-pass filter, multiple feedback type 2 nd order band-pass filter includes: the multi-feedback type 2-order low-pass filter circuit and the voltage follower circuit at the front stage and the multi-feedback type 2-order high-pass filter circuit and the voltage follower circuit at the rear stage; the front stage and the rear stage are cascaded to form the multiple feedback type 2-order band-pass filter;
and the output end of the band-pass filter circuit is connected with the battery internal resistance tester so as to transmit the amplified alternating voltage signal subjected to interference filtering to the battery internal resistance tester.
2. The low-noise differential amplification filter circuit for the high-precision weak signal as claimed in claim 1, wherein the amplification factor selection circuit selects different access resistors by switching to set corresponding amplification factors.
3. The low-noise differential amplification filter circuit for the high-precision weak signal as claimed in claim 2, wherein the amplification factor selection circuit adopts a differential multi-channel digital control analog switch, and the external gain resistor is gated by the analog switch.
4. The low-noise differential amplification filter circuit for high-precision weak signals according to claim 1, wherein the multi-feedback 2-order low-pass filter circuit and the voltage follower circuit of the front stage comprise: the negative input end of the first operational amplifier is connected with the output end of the alternating current differential amplification circuit through a resistor, and the positive input end of the first operational amplifier is grounded through a resistor; the output end of the first operational amplifier is connected with the positive input end of the second operational amplifier, and the negative input end and the output end of the second operational amplifier are in short circuit.
5. The high-precision weak-signal low-noise differential amplification filter circuit as claimed in claim 4, wherein the post-stage multi-feedback 2-order high-pass filter circuit and the voltage follower circuit comprise: the negative input end of the third operational amplifier is connected with the output end of the second operational amplifier through a resistor and a capacitor, the positive input end of the third operational amplifier is grounded through a resistor, the positive input end of the fourth operational amplifier is connected with the output end of the third operational amplifier, the negative input end of the fourth operational amplifier is in short circuit with the output end, and the output end of the fourth operational amplifier is connected with the battery internal resistance tester.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202023153499.XU CN213846617U (en) | 2020-12-24 | 2020-12-24 | Low-noise differential amplification filter circuit for high-precision weak signals |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202023153499.XU CN213846617U (en) | 2020-12-24 | 2020-12-24 | Low-noise differential amplification filter circuit for high-precision weak signals |
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| CN213846617U true CN213846617U (en) | 2021-07-30 |
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| CN202023153499.XU Expired - Fee Related CN213846617U (en) | 2020-12-24 | 2020-12-24 | Low-noise differential amplification filter circuit for high-precision weak signals |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113765490A (en) * | 2021-08-17 | 2021-12-07 | 上海卫星装备研究所 | Pre-amplification circuit for output end of induction synchronizer and induction synchronizer |
| CN116930800A (en) * | 2023-09-18 | 2023-10-24 | 湖南恩智测控技术有限公司 | Fuel cell impedance measuring device and method |
-
2020
- 2020-12-24 CN CN202023153499.XU patent/CN213846617U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113765490A (en) * | 2021-08-17 | 2021-12-07 | 上海卫星装备研究所 | Pre-amplification circuit for output end of induction synchronizer and induction synchronizer |
| CN113765490B (en) * | 2021-08-17 | 2023-11-10 | 上海卫星装备研究所 | Pre-amplifying circuit for output end of induction synchronizer and induction synchronizer |
| CN116930800A (en) * | 2023-09-18 | 2023-10-24 | 湖南恩智测控技术有限公司 | Fuel cell impedance measuring device and method |
| CN116930800B (en) * | 2023-09-18 | 2023-12-19 | 湖南恩智测控技术有限公司 | Fuel cell impedance measuring device and method |
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20210730 Termination date: 20211224 |
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| CF01 | Termination of patent right due to non-payment of annual fee |