Multistage filtering and amplifying circuit
By using a multi-stage filtering and amplification circuit, the problems of weak signals and insufficient anti-electromagnetic interference capability of magnetostrictive sensors are solved, achieving efficient signal amplification and improved stability, making it suitable for signal detection in complex environments.
Patent Information
- Application Number
- CN202520540073.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2026-02-27
- Estimated Expiration
- 2035-03-26
AI Technical Summary
Existing magnetostrictive sensors suffer from weak output signals, noise introduction due to single-stage amplification, lack of frequency band hierarchical filtering optimization, and insufficient resistance to electromagnetic interference, resulting in large signal processing errors and poor stability.
A multi-stage filtering and amplification circuit was designed, including first-stage, second-stage, and third-stage amplification and filtering modules. These modules employ a first-stage amplifier, an adjustable-gain amplifier, and a high-precision instrumentation amplifier, respectively. The circuit utilizes low-pass filters, band-pass filters, and EMI filters for graded filtering and amplification, thereby optimizing signal processing.
It achieves graded amplification and filtering of signals in different frequency bands, reduces noise interference, improves signal detection sensitivity and anti-electromagnetic interference capability, ensures signal stability, and expands the applicability of the equipment.
Smart Images
Figure CN223957522U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to a kind of circuit modules, in particular to a kind of multistage filter amplification circuit. BACKGROUND
[0002] The magnetostrictive sensor is a kind of device for measuring the actual displacement of the measured product, which acts on the sensitive element inside the protective tube through the non-contact magnetic ring outside the protective tube, so that mechanical pulse signals are generated, and the pulse signals are transmitted to the electronic chamber through the waveguide tube. The electronic chamber can accurately detect the distance of the magnetic ring by measuring the transmission time of the mechanical pulse signal.
[0003] Although the existing magnetostrictive sensor can detect displacement values, there are still some problems in actual application. Specifically, because the output signal of the magnetostrictive sensor is relatively weak, the output signal needs to be amplified by an amplifier during application so that the subsequent circuit module can process the signal. The existing magnetostrictive sensor often uses a single-stage amplification circuit to amplify the signal. This modular design of the amplification circuit lacks hierarchical filtering optimization for different frequency bands, and the single-stage amplification is prone to introduce noise, which in turn leads to large subsequent processing errors. In addition, the existing magnetostrictive sensor does not use an anti-electromagnetic interference design, which reduces its anti-electromagnetic interference capability and makes the signal stability poor when it is applied in complex industrial environments. Therefore, a new filter amplification circuit needs to be designed to solve the above problems. SUMMARY
[0004] To solve the above technical problems, the utility model provides a kind of multistage filter amplification circuit, which can amplify and filter different frequency band signals to reduce noise interference and processing error, improve signal detection sensitivity and have strong anti-electromagnetic interference capability.
[0005] The multistage filter amplification circuit of the utility model, including one-stage amplification filter module, multistage filter amplification circuit further includes two-stage amplification filter module and three-stage amplification filter module, the one-stage amplification filter module includes one-stage amplifier, the input end of one-stage amplifier is used to connect input signal, the output end of one-stage amplification circuit is connected with first low pass filter, the two-stage amplification filter module includes two-stage amplifier, the output end of one-stage amplifier is connected with the input end of two-stage amplifier, the output end of two-stage amplifier is connected with band pass filter, the three-stage amplification filter module includes three-stage amplifier, the input end of three-stage amplifier is connected with band pass filter, the output end of three-stage amplifier is connected with EMI filter, EMI filter includes magnetic bead with one end connected with three-stage amplifier and the other end connected with capacitor, the other end of magnetic bead is connected with signal output end.
[0006] The multi-stage filter amplification circuit has the advantages that the multi-stage filter amplification circuit is composed of the one-stage amplification filter module, the two-stage amplification filter module and the three-stage amplification filter module, the three-stage amplification filter is cooperatively optimized, the signal noise can be greatly reduced, the output signal amplitude and precision are improved, the noise accumulation problem caused by single-stage amplification is avoided, meanwhile, the EMI filter in the three-stage amplification filter module can greatly improve the anti-electromagnetic interference capability of the circuit, so that the device can still maintain the stability of the output signal when applied in a complex environment, and the detection sensitivity of the system is improved, and the application range of the device is expanded.
[0007] Further, the multi-stage filter amplification circuit has a second low-pass filter arranged at the output end of the one-stage amplifier, the second low-pass filter comprises a resistor and a capacitor connected in series, one end of the second low-pass filter is connected with the output end of the first amplifier, and the other end is grounded.
[0008] The design of the second low-pass filter further improves the filtering effect of the one-stage amplification filter module on high-frequency signals, and ensures the signal purity.
[0009] Further, the multi-stage filter amplification circuit has a two-stage amplifier which is an adjustable gain amplifier.
[0010] The adjustable gain amplifier facilitates the adjustment of the gain of the second amplifier by an operator, so as to meet the design requirements of the system.
[0011] Further, the multi-stage filter amplification circuit has an input end of the two-stage amplifier connected with the output end of the one-stage amplifier through a shielded signal line.
[0012] The shielded signal line further improves the anti-electromagnetic interference capability of the system, so that the system can work normally under complex working conditions, and the environmental adaptability is improved.
[0013] Further, the multi-stage filter amplification circuit has a band-pass filter which is an LC band-pass filter.
[0014] The above description is only a summary of the technical scheme of the utility model, in order to more clearly understand the technical means of the utility model, and according to the content of the specification, the following embodiment of the utility model is described in detail. BRIEF DESCRIPTION OF DRAWINGS
[0015] Fig. 1 It is the principle diagram of the multi-stage filter amplification circuit.
[0016] Fig. 2 It is the partial principle diagram of the one-stage amplification filter module.
[0017] Fig. 3 is a partial schematic diagram of a two-stage amplification filtering module.
[0018] Fig. 4 is a partial schematic diagram of a three-stage amplification filtering module.
[0019] In the figure, the first-stage amplification filtering module 1, the two-stage amplification filtering module 2, the three-stage amplification filtering module 3, the first-stage amplifier 4, the first low-pass filter 5, the second-stage amplifier 6, the band-pass filter 7, the third-stage amplifier 8, the EMI filter 9, the magnetic bead 10, the magnetostrictive sensor output port 11, the adjustable resistor 12, the BNC interface 13, and the second low-pass filter 14. DETAILED DESCRIPTION
[0020] The specific implementation of the utility model will be described in further detail below in combination with the drawings and examples. The following examples are used to illustrate the utility model, but not to limit the scope of the utility model.
[0021] Example 1: Referring to Figs. 1 to 4 The multi-stage filtering amplification circuit of the embodiment comprises a first-stage amplification filtering module 1. The multi-stage filtering amplification circuit further comprises a two-stage amplification filtering module 2 and a three-stage amplification filtering module 3. The first-stage amplification filtering module comprises a first-stage amplifier 4. The input end of the first-stage amplifier is used to connect an input signal. The output end of the first-stage amplification circuit is connected with a first low-pass filter 5. The two-stage amplification filtering module comprises a second-stage amplifier 6. The input end of the second-stage amplifier is connected with the output end of the first-stage amplifier. The output end of the second-stage amplifier is connected with a band-pass filter 7. The three-stage amplification filtering module comprises a third-stage amplifier 8. The input end of the third-stage amplifier is connected with the band-pass filter. The output end of the third-stage amplifier is connected with an EMI filter 9. The EMI filter comprises a magnetic bead 10 connected with the third-stage amplifier at one end and connected with a capacitor at the other end. The other end of the magnetic bead is connected with a signal output end.
[0022] The multi-stage filtering amplification circuit has the advantages that the multi-stage filtering amplification circuit realizes multi-stage amplification filtering of the input signal through the first-stage amplification filtering module, the two-stage amplification filtering module, and the three-stage amplification filtering module. The three-stage amplification filtering is optimized in cooperation, which can greatly reduce the signal noise, improve the output signal amplitude and precision, and avoid the noise accumulation problem caused by single-stage amplification. At the same time, the setting of the EMI filter in the three-stage amplification filtering module can greatly improve the anti-electromagnetic interference ability of the circuit, so that the device can still maintain the stability of the output signal when applied in a complex environment, thereby improving the detection sensitivity of the system and expanding the application range of the device.
[0023] The first-stage amplification filter module realizes amplification and low-pass filtering of the original input signal through a first-stage amplifier and a first low-pass filter. In this embodiment, the first-stage amplifier is an AD8646WARMZ-R7 precision operational amplifier, the negative phase input end of which is connected to the negative end of the output port 11 of the magnetostrictive sensor through a resistor, and the positive phase input end is connected to the positive end of the output port of the magnetostrictive sensor through a resistor.
[0024] The output end of the first-stage amplifier is connected in series with the first low-pass filter. Preferably, the first low-pass filter is an RC low-pass filter, which specifically includes a resistor Rf1 and a capacitor Cf. The resistor Rf1 and the capacitor Cf are connected in parallel and arranged between the output end and the negative phase input end of the first-stage amplifier, thereby forming an active low-pass filter with the first-stage amplifier, and further realizing filtering of high-frequency noise.
[0025] In order to further improve the filtering effect of high-frequency noise, the output end of the first-stage amplifier can be further connected in parallel with a second low-pass filter 14. The second low-pass filter includes a resistor and a capacitor connected in series, one end of which is connected to the output end of the first-stage amplifier, and the other end is grounded, so as to further filter high-frequency noise and ensure signal purity.
[0026] The second-stage amplification filter module realizes further amplification and noise filtering of the signal through a second-stage amplification circuit and a band-pass filter. In this embodiment, the second-stage amplifier is an AD623 gain-adjustable amplifier, the positive phase input end of which is connected to the output of the first-stage amplification filter module through a shielded signal line, and the negative phase input end is grounded. The second-stage amplifier can realize amplification and gain adjustment of the signal to meet the design requirements of signal gain. In specific implementation, an adjustable resistor 12 is connected between the 1 pin and the 8 pin of the second-stage amplifier. The operator can adjust the size of the gain through the adjustable resistor to meet the specific design requirements of the system.
[0027] The signal output by the second-stage amplifier is output to the third-stage amplification filter module through the band-pass filter to realize further filtering of signal noise. In this embodiment, the band-pass filter is an LC band-pass filter connected in series between the output end of the second-stage amplifier and the input end of the third-stage amplifier. The operator can select appropriate inductance and capacitance according to the system requirements, and then realize an LC band-pass filter with a certain center frequency and bandwidth to suppress out-of-band interference signals.
[0028] The third-stage amplification filter module realizes further amplification and noise filtering of the signal through a third-stage amplifier and an EMI filter. In this embodiment, the third-stage amplifier is an INA128 high-precision instrument amplifier, the positive phase input end of which is connected to the output end of the second-stage amplification filter module, the negative phase input end is grounded, and the output end is connected to the EMI filter to further eliminate electromagnetic interference and suppress high-frequency noise.
[0029] The final signal filtered by the EMI filter is output to a signal output end, i.e. a BNC interface 13, through the other end of the magnetic bead, so as to be processed by subsequent equipment.
[0030] The parameter values of the components in the first low-pass filter, the band-pass filter and the EMI filter are obtained according to the specific design requirements of the system and formula calculation. The cut-off frequency of the RC filter is f=1 / (2πRC), the center frequency of the band-pass filter is f0=1 / (2π√(LC)), and the bandwidth is Δf=1 / (2π√(LC)).
[0031] wherein R load is the load impedance, and in addition, the gain multiples of the amplifiers are designed according to the specific design requirements, and the specific parameter selection and calculation process is a conventional technique, which is not described herein.
[0032] The above only describes the preferred embodiments of the present application, which are used to assist the skilled in the art to realize the corresponding technical solutions, and are not used to limit the protection scope of the present application. The protection scope of the present application is defined by the appended claims. It should be noted that, for the ordinary skilled in the art, on the basis of the technical solutions of the present application, a number of equivalent improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present application. Meanwhile, it should be understood that, although the present application is described according to the above embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity. The skilled in the art should regard the specification as a whole, and the technical solutions of each embodiment can be properly combined to form other embodiments which can be understood by the skilled in the art.
Claims
1. A multi-stage filter-amplifier circuit comprising a first stage of an amplification filter module (1), characterized in that: The multi-stage filter amplification circuit further comprises a second-stage amplification filter module (2) and a third-stage amplification filter module (3), the first-stage amplification filter module comprises a first-stage amplifier (4), an input end of the first-stage amplifier is used for connecting an input signal, and an output end of the first-stage amplifier is connected with a first low-pass filter (5), the second-stage amplification filter module comprises a second-stage amplifier (6), an input end of the second-stage amplifier is connected with an output end of the first-stage amplifier, an output end of the second-stage amplifier is connected with a band-pass filter (7), and the third-stage amplification filter module comprises a third-stage amplifier (8), an input end of the third-stage amplifier is connected with the band-pass filter, and an output end of the third-stage amplifier is connected with an EMI filter (9), the EMI filter comprises a magnetic bead (10) having one end connected with the third-stage amplifier and the other end connected with a capacitor, and the other end of the magnetic bead is connected with a signal output end.
2. The multi-stage filter amplifier circuit of claim 1, wherein: The first low-pass filter is an RC low-pass filter, the RC low-pass filter comprises a resistor Rf1 and a capacitor Cf, and the resistor Rf1 and the capacitor Cf are connected in parallel and arranged between an output end and a negative phase input end of the first-stage amplifier.
3. The multi-stage filter amplifier circuit of claim 2, wherein: The output end of the first-stage amplifier is further provided with a second low-pass filter, the second low-pass filter comprises a resistor and a capacitor connected in series, one end of the second low-pass filter is connected with the output end of the first-stage amplifier, and the other end is grounded.
4. The multi-stage filter amplifier circuit of claim 1, wherein: The second-stage amplifier is an adjustable gain amplifier.
5. The multi-stage filter amplifier circuit of claim 1, wherein: The input end of the second-stage amplifier is connected with the output end of the first-stage amplifier through a shielding signal line.
6. The multi-stage filter amplifier circuit of claim 1, wherein: The band-pass filter is an LC band-pass filter.