Electronic circuit with transmission line type noise filter

Abstract

The invention relates to the technical field of noise filtering, in particular to an electronic circuit with a transmission line type noise filter, and the electronic circuit comprises a frequency determination device which is used for determining the working frequency and voltage of the electronic circuit; the device determining device is used for selecting a microstrip line as a transmission line and optimizing the filter by using a composite right / left hand transmission line and an open-circuit T-shaped structure; the impedance matching device is used for matching the impedance of the filter with the impedance of the transmission line; the matching measuring device is used for measuring the impedance matching effect by using a reflection coefficient and a VSWR (Voltage Standing Wave Ratio); and the software simulation device is used for simulating and optimizing the matched filter and transmission line by using simulation software. According to the invention, the impedance of the filter is matched with the impedance of the transmission line, so that the impedance change of the signal in the transmission process is reduced, the reflection of the signal is reduced, and the transmission quality and efficiency of the signal are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of filtering noise, and particularly to an electronic circuit having a transmission line type noise filter. Background Art

[0002] With the continuous development of communication technologies, people's requirements for the anti-interference ability and noise suppression level of communication devices are getting higher and higher. During the communication process, analog signals are interfered by environmental noise and system noise, and these noises will seriously affect the ability of the communication system to receive the minimum signal and the working level of subsequent signal processing and analysis. In order to improve the communication quality, effective noise suppression technologies need to be adopted, and the transmission line type noise filter is an important tool to meet this requirement.

[0003] At the connection between the filter and other circuits, impedance mismatch will cause signal reflection and increased loss, thereby affecting the signal transmission quality and the stability of the system. Therefore, when designing the filter, it is necessary to fully consider the impedance matching problem to ensure that the input and output impedances of the filter are consistent with the impedance of the signal source or load.

[0004] In practical applications, impedance mismatch often occurs at the connection between the filter and other circuits. This is because the impedance matching problem is not fully considered during circuit design, resulting in impedance characteristic mismatch between the filter and the front and rear stage circuits. In addition, as the usage time of circuit components increases, they will gradually age and their performance parameters will change, thereby affecting the input and output impedances of the filter and making them no longer consistent with the impedance of the signal source or load. In addition, poor connections between the filter and other circuits, such as poor contact and damaged connection lines, also cause changes in impedance characteristics, further exacerbating the impedance mismatch problem. Summary of the Invention

[0005] The present invention provides an electronic circuit having a transmission line type noise filter to solve the defect of impedance mismatch between the filter impedance and the transmission line impedance in the prior art.

[0006] On the one hand, the present invention provides an electronic circuit having a transmission line type noise filter, including: A frequency determination device for determining the operating frequency and voltage of the electronic circuit; A device determination device for selecting a microstrip line as the transmission line and optimizing the filter using a composite left-handed and right-handed transmission line and an open-circuit T-shaped structure; An impedance matching device, comprising an impedance measurement module, a selection method module, a device connection module, and an interference reduction module; the impedance measurement module is used to measure the input impedance and output impedance of a filter using a vector network analyzer, and measure the characteristic impedance of a microstrip line; the selection method module is used to select a matching method for the impedance of the filter and the impedance of the transmission line according to the type of the filter, the operating frequency, and the impedance of the microstrip line; the device connection module is used to connect the filter and the microstrip line according to the matching method; the interference reduction module is used to adjust a common mode choke and a Y capacitor to reduce electromagnetic interference suppression of a computer motherboard; A matching measurement device, used to measure the effect of the impedance matching device using a reflection coefficient and a voltage standing wave ratio, so that the signal transmission efficiency through the filter reaches the maximum and energy reflection is reduced; A software simulation device, used to perform circuit simulation on the matched filter and transmission line using simulation software, and adjust and optimize the transmission line parameters and filter element values according to the simulation results.

[0007] On the other hand, the present invention also provides an electronic circuit with a transmission line type noise filter, and the device determination device includes: a transmission line selection module, using a microstrip line that meets a preset reflection coefficient standard as the transmission line of the filter, and calculating the impedance of the required microstrip line; A composite left-right hand module, adopting an ultra-wideband filter with a composite left-right hand transmission line structure, adjusting the size of interdigital capacitors according to the power and frequency of a preset filter to achieve narrowband and broadband adjustment of the filter; An open-circuit T-shaped module, optimizing the frequency response of the filter by adjusting the arm length and width of the open-circuit T-shaped structure; simplifying the size of the filter by combining a microstrip line and a coplanar waveguide, and generating negative permittivity and negative permeability using a composite material; A line length determination module, determining the length of the transmission line according to a quarter wavelength of the filtering frequency.

[0008] On the other hand, the present invention also provides an electronic circuit with a transmission line type noise filter, and the calculation formula for the impedance of the microstrip line in the transmission line selection module is:

[0009] In the formula, Z0 is the characteristic impedance, w is the line width of the microstrip line, t is the thickness of the metal, h is the dielectric thickness, ɛ r is the relative permittivity of the dielectric.

[0010] On the other hand, the present invention also provides an electronic circuit with a transmission line type noise filter, and the selection method module includes: A small difference impedance unit, used to directly connect the impedance of the filter and the impedance of the transmission line when the data difference between the impedance of the filter and the impedance of the transmission line is less than a preset value; A large-difference impedance unit is used to adjust the transmission parameters of a filter to optimize impedance matching when the impedance difference between the filter and the transmission line is greater than a preset value, and a PI matching network is used to optimize the impedance matching between the filter and the transmission line.

[0011] On the other hand, the present invention also provides an electronic circuit having a transmission line type noise filter. The large-difference impedance module includes: A determining frequency subunit for determining the working center frequency of the PI matching network according to the frequency characteristics of the computer motherboard; A selecting device subunit for calculating the quality factor of the PI type matching network, measuring the energy storage and loss of the capacitor and inductor in the filter according to the quality factor, and selecting the inductor and capacitor that meet the computer motherboard standard; A calculating device subunit for calculating the required inductor and capacitor values according to the impedance matching formula.

[0012] On the other hand, the present invention also provides an electronic circuit having a transmission line type noise filter. In the selecting device subunit, the calculation formula for the quality factor is:

[0013] In the formula, R is the resistance, f0 is the resonant frequency, L is the capacitance, l is the conductor length, ρ is the resistivity, and A is the cross-sectional area of the conductor.

[0014] On the other hand, the present invention also provides an electronic circuit having a transmission line type noise filter. The calculating device subunit calculates the parallel impedance according to the resistance and capacitance at the input end and the resistance and capacitance at the output end in the parallel impedance matching formula, calculates the series impedance according to the resistance and reactance at the input end and the resistance and reactance at the output end in the series impedance matching formula, and calculates the level conversion impedance according to the conductor resistance, the angular frequency inductance, capacitance, and temperature of the signal in the level conversion impedance matching formula.

[0015] On the other hand, the present invention also provides an electronic circuit having a transmission line type noise filter. The parallel impedance matching formula is expressed as:

[0016] R1 and L1 are the resistance and capacitance at the input end, R2 and L2 are the resistance and capacitance at the output end, f is the frequency, and R and X are the matched resistance and reactance.

[0017] On the other hand, the present invention also provides an electronic circuit having a transmission line type noise filter. The level conversion impedance matching formula is:

[0018] Wherein, Z is the total circuit impedance, l is the conductor length, ρ is the resistivity, A is the cross-sectional area of the conductor, ω is the angular frequency of the signal, L is the inductance in the circuit, C is the capacitance in the circuit, t is the temperature, and α is the temperature coefficient of resistance, is the resistance value at a temperature of 0.

[0019] On the other hand, the present invention also provides an electronic circuit having a transmission line type noise filter, and the matching measurement device includes: a reflection coefficient module and a voltage standing wave ratio module; The calculation formula of the reflection coefficient module is:

[0020] Wherein, ZL is the changed impedance, and ZO is the impedance before change. If the load and the transmission line are completely matched, then K = 0, indicating no signal reflection; The calculation formula of the voltage standing wave ratio module is:

[0021] Wherein, K is the reflection coefficient.

[0022] For the electronic circuit with a transmission line type noise filter provided by the present invention, by making the impedance of the device match the impedance of the transmission line, the impedance change encountered by the signal during transmission will be greatly reduced, thereby reducing signal reflection. Signal reflection is the echo generated when the signal encounters impedance discontinuity on the transmission line, which will interfere with the original signal and cause the signal quality to decline. Through impedance matching, it is ensured that the signal propagates smoothly on the transmission line and unnecessary reflections are avoided. Impedance matching also improves the signal transmission efficiency. When the impedance matching is good, the signal can be transmitted on the transmission line with less loss, and even theoretically achieve lossless transmission. This means that more signal energy can reach the load end, thereby improving the signal transmission quality and efficiency. The performance of the filter depends to a large extent on its impedance matching degree. When the impedance of the filter matches the impedance of the transmission line, the filter can better play its filtering role and effectively filter and suppress signals of specific frequencies. This helps to ensure the signal quality in the system and avoid the influence of interference and noise. Impedance matching also enhances the stability of the system. In high-frequency circuits, impedance mismatch leads to signal oscillation and instability. By optimizing impedance matching, it is ensured that the signal in the system remains stable during transmission, thereby enhancing the overall performance and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0024] Figure 1 is a block diagram of an electronic circuit with a transmission line type noise filter provided by an embodiment of the present invention; Figure 2 is a block diagram of an impedance matching device of the present invention. Detailed implementation manners

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are some, rather than all, embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts fall within the scope of protection of the present invention.

[0026] As Figure 1 shown, the electronic circuit with a transmission line type noise filter provided by an embodiment of the present invention mainly includes: A frequency determination device for determining the operating frequency and voltage of the electronic circuit.

[0027] Taking the electromagnetic vibration noise of a computer motherboard as an example, the electromagnetic vibration noise is caused by the tiny vibrations of electronic components on the motherboard under the action of an electromagnetic field, such as components like inductors, capacitors, and transformers. The frequency range of the electromagnetic vibration noise varies from several hundred Hz to several MHz. The electromagnetic vibration noise frequency generated by some inductors in switching power supplies during operation is between 100 Hz and 30 kHz. The intensity of the electromagnetic vibration noise is relatively weak, generally between 10 dB - 30 dB, but under certain specific conditions, such as poor component quality, unreasonable circuit design, or the presence of electromagnetic interference, the intensity will increase. The voltage of electronic components during operation varies depending on the component type and circuit design. The core voltage of the CPU on a computer motherboard is generally between 0.5 V - 1.5 V.

[0028] A device determination device for selecting a microstrip line as the transmission line and optimizing the filter using a composite right - hand and left - hand transmission line and an open - circuit T - type structure.

[0029] When selecting a transmission line, a microstrip line suitable for high-frequency and high-speed signal transmission and filtering is chosen. The microstrip line not only has a smaller size, which is convenient for integration in a compact space, but also has low-loss characteristics, which can ensure the quality and integrity of the signal during transmission. Especially in such a high-frequency band, the microstrip line filter can efficiently filter out unwanted stray signals and interference, significantly improving the signal-to-noise ratio and overall performance of the communication system, thereby ensuring the stability and reliability of wireless communication. When designing the microstrip line, its electromagnetic compatibility is considered, and its characteristic impedance and transmission delay time are controlled by optimizing its structural parameters, such as the thickness and width of the line, the distance from the ground layer, and the relative permittivity of the dielectric, so as to ensure the stability and integrity of the signal during transmission.

[0030] Select a transmission line module and use a microstrip line material with a higher reflection coefficient to reduce the loss of the filter. Materials with a higher reflection coefficient have lower dielectric losses, which helps to reduce the energy loss of the signal during transmission.

[0031] The calculation formula for the impedance of the microstrip line is:

[0032] In the formula, Z0 is the characteristic impedance, w is the width of the microstrip line, t is the thickness of the metal, h is the dielectric thickness, and ɛ r is the relative permittivity of the dielectric.

[0033] The phase constant β:

[0034] In the formula, ω is the angular frequency, μ is the magnetic permeability, and ɛ is the permittivity.

[0035] The composite left-handed and right-handed module uses a composite left-handed and right-handed transmission line structure to realize the design of an ultra-wideband filter, and has the advantages of low insertion loss and compact size. By changing the size of the interdigital capacitor, narrowband and broadband characteristics can be achieved. The calculation formula for the interdigital capacitor is:

[0036] In the formula, A is the area of the capacitor plate, d is the distance between the plates, ɛ is the permittivity, and different dielectrics have different permittivities.

[0037] The open-circuit T-type module optimizes the frequency response of the filter by adjusting the arm length and width of the open-circuit T-type filter, shortens the arm length of the T-type structure, reduces the overall size of the filter, and increases the width of the T-type structure to improve its capacitance effect, which helps to expand the stopband width. The input and output ports and matching network of the filter are made of coplanar waveguide to optimize the performance of the filter.

[0038] The impedance matching device includes a line length determination module, an impedance measurement module, and a selection method module.

[0039] The specific steps for the line length determination module to match the impedance of the filter with that of the transmission line are as follows: The impedance measurement module is used to measure the input and output impedances of the filter and the characteristic impedance of the microstrip line using a vector network analyzer.

[0040] The selection method module is used to select a method for matching the impedance of the filter with that of the transmission line according to the type of the filter, the operating frequency, and the impedance of the microstrip line.

[0041] The small difference impedance unit is used to analyze the impedance difference between the filter and the load based on the measured impedance values. If the impedance of the filter is very close to that of the transmission line, they can be directly connected without an additional matching network.

[0042] For example, in an LC low-pass filter, its output impedance is:

[0043] In the formula, ω is the angular frequency, L is the inductance, and C is the capacitance.

[0044] The large difference impedance unit is used to change the signal transmission parameters to optimize impedance matching when the impedance difference between the filter impedance and the transmission line impedance is large, and use a PI matching network to match the impedance of the filter with that of the transmission line.

[0045] The specific steps for designing a PI-type matching network are as follows: The frequency determination subunit is used to determine the center operating frequency of the PI matching network according to the frequency characteristics of the computer motherboard.

[0046] The device selection subunit is used to calculate the quality factor of the PI matching network, measure the energy storage and loss of the capacitor and inductor in the filter according to the quality factor, and select appropriate inductors and capacitors.

[0047] The calculation formula for the quality factor is:

[0048] In the formula, R is the resistance, f0 is the resonant frequency, L is the capacitance, l is the conductor length, ρ is the resistivity, and A is the cross-sectional area of the conductor.

[0049] The device calculation subunit is used to calculate the required inductor and capacitor values according to the impedance matching principle and impedance matching formula.

[0050] Impedance matching refers to a working state where the load impedance is adapted to the internal impedance of the excitation source to obtain maximum power output. When the load impedance is equal to the characteristic impedance of the transmission line, the signal on the transmission line will not be reflected, and all the energy will be absorbed by the load. This state is called "matching". When the load impedance is not equal to the characteristic impedance of the transmission line, the signal on the transmission line will be reflected, and part of the energy will be reflected back to the source point, resulting in signal reflection, rebound, and loss. The original good signal waveform will be distorted, directly affecting the performance of the circuit.

[0051] The calculation device unit includes a parallel impedance matching formula, a series impedance matching formula, and a level conversion impedance matching formula.

[0052] The parallel impedance matching formula is:

[0053] R1 and L1 are the resistance and capacitance at the input end, R2 and L2 are the resistance and capacitance at the output end, f is the frequency, and R and X are the resistance and reactance after matching.

[0054] The series impedance matching formula is:

[0055]

[0056] In the formula, R1 and X1 are the resistance and reactance at the input end, R2 and X2 are the resistance and reactance at the output end, and R and X are the resistance and reactance after matching.

[0057] In a specific embodiment, the impedance of the filter and the impedance of the transmission line are affected by temperature and noise.

[0058] The filter is mainly composed of inductors and capacitors, and the performance of the inductors and capacitors determines the overall performance of the filter. Temperature changes will cause the resistance value of the metal conductor to change with temperature. The resistance value of the metal increases with the increase of temperature. Because the conduction electrons of the metal conductor will collide and scatter after being heated, resulting in an increase in the resistance to current, and the resistance value also increases accordingly.

[0059] The level conversion impedance matching formula is:

[0060] In the formula, Z is the total impedance of the circuit, l is the conductor length, ρ is the resistivity, A is the cross-sectional area of the conductor, ω is the angular frequency of the signal, L is the inductance in the circuit, C is the capacitance in the circuit, t is the temperature, α is the temperature coefficient of the resistance, is the resistance value at a temperature of 0.

[0061] High-frequency noise can cause additional losses in the capacitor and inductor components of the filter. These losses can lead to changes in the impedance characteristics of the filter, thereby affecting its filtering effect. Noise also affects the internal circuit structure of the filter, changing the charge and discharge rate of the capacitor or affecting the magnetic field distribution of the inductor, thus causing changes in the impedance value of the filter. This mismatch can cause signal reflection and loss during transmission, thereby affecting the signal transmission quality and the stability of the system. Due to changes in temperature and the impedance of the filter and connecting wires, the originally designed impedance matching will fail, resulting in problems such as increased signal reflection and loss.

[0062] The specific steps for controlling impedance matching using a feedback adjustment circuit are as follows: Select the emitter negative feedback circuit in the differential amplifier as the feedback circuit for the transmission line type noise filter.

[0063] Connect a capacitor or inductor in series or parallel at the load end, and use a transformer to adjust the value of the load resistance to make the filter impedance match the connecting wire impedance.

[0064] Precisely, impedance matching ensures that the signal is transmitted between the filter and the transmission line without reflection, avoiding the loss of signal energy. When the impedance of the filter is equal to the impedance of the transmission line, the signal is transmitted to the load end to the maximum extent without reflection, and reflection will cause signal distortion, increased noise, and reduced transmission efficiency, thereby improving the signal transmission efficiency.

[0065] The device connection module is used to connect the filter to the microstrip line according to the selected matching method. Ensure that the connection is tight and reliable to reduce signal loss. For the case of using a transmission line transformer, it is necessary to correctly connect the input and output ports of the transformer.

[0066] Reserve a suitable position for the integrated circuit on the circuit board to ensure that it can dissipate heat normally and maintain good electrical connection with other components. Adjust the values of electronic components such as capacitors and inductors in the filter to change its impedance characteristics, so as to match the impedance of the transmission line or load.

[0067] The interference reduction module is used to reduce electromagnetic interference suppression using a common mode choke and a Y capacitor.

[0068] In the process of designing a filter, it is necessary to comprehensively consider the suppression strategies for common-mode noise and differential-mode noise to ensure the quality and stability of signal transmission. By using special components such as common-mode chokes and Y capacitors, these two types of noise can be efficiently separated and their interference effectively suppressed. The common-mode choke, through its unique winding method and inductance characteristics, generates a significant impedance to common-mode noise, thus effectively reducing its propagation in the system. At the same time, the Y capacitor, by virtue of its connection between the power line and the ground, provides a low-impedance path for common-mode noise, enabling it to be safely guided to the ground and further reducing the impact of noise on the system. Therefore, in the design of a filter, reasonably utilizing components such as common-mode chokes and Y capacitors is a key measure to improve the filter performance and ensure the electromagnetic compatibility of the system. It is widely applied on power lines and signal lines to reduce the impact of electromagnetic noise on the system. It is usually composed of components such as inductors and capacitors to form a low-pass filter structure to attenuate high-frequency noise signals.

[0069] A matching measurement device is used to measure the effect of impedance matching using the reflection coefficient and VSWR, quantitatively analyze the impedance matching degree between the signal source and the load in the circuit system, and ensure the maximization of signal transmission efficiency and reduce energy reflection.

[0070] The reflection coefficient module is an important indicator for measuring the amount of signal reflection. The calculation formula for the reflection coefficient is:

[0071] In the formula, Z L is the changed impedance, and Z O is the impedance before change. If the load and the transmission line are completely matched, then K = 0, indicating no signal reflection.

[0072] The voltage standing wave ratio module is an indicator for measuring the impedance matching degree. VSWR is the ratio of the voltage amplitude at the standing wave antinode to the voltage amplitude at the node. The calculation formula for the voltage standing wave ratio is:

[0073] In the formula, K is the reflection coefficient.

[0074] When VSWR = 1, it indicates that the impedance of the feeder and the antenna is completely matched. At this time, all the high-frequency energy is radiated by the antenna, and there is no reflection loss of energy.

[0075] The software simulation device is used to simulate and optimize the electronic circuit with a transmission line type noise filter using simulation software.

[0076] A transmission line type noise filter is set inside the electronic circuit to minimize the propagation path of noise. Ensure good electrical connection between the filter and other components to avoid unnecessary interference. Use professional circuit simulation software such as ADS, Multisim, etc. to establish the designed transmission line filter circuit and related electronic component models, including the electrical parameters of the transmission line, the characteristics of the filtering components, etc.

[0077] Conduct frequency response analysis, time-domain analysis, noise analysis, etc. on the circuit to observe whether the filtering effect of the filter meets the design objectives. For example, through frequency response analysis, obtain the amplitude-frequency characteristic curve of the filter to visually view the attenuation at different frequencies.

[0078] According to the simulation results, adjust and optimize the transmission line parameters, filter component values, etc. to improve the performance of the filter. For example, if the filtering effect in a certain frequency band is not ideal, appropriately adjust the value of the inductor or capacitor, or change the length and characteristic impedance of the transmission line, and re-perform the simulation until a satisfactory filtering effect is achieved.

[0079] Ensure good connection between the filter and other circuits to avoid problems such as poor contact, insecure soldering, or looseness. Use high-quality connectors and cables to reduce impedance mismatch and signal loss at the connection points.

[0080] In the electronic circuit with a transmission line type noise filter provided by the present invention, by matching the impedance of the filter with the impedance of the transmission line, the impedance change encountered by the signal during transmission will be greatly reduced, thereby reducing signal reflection. Signal reflection is the echo generated when the signal encounters impedance discontinuity on the transmission line, which will interfere with the original signal and cause signal quality degradation. Through impedance matching, ensure the smooth propagation of the signal on the transmission line and avoid unnecessary reflections. Impedance matching also improves the transmission efficiency of the signal. When the impedance matching is good, the signal can be transmitted on the transmission line with less loss, and even theoretically achieve lossless transmission. This means that more signal energy can reach the load end, thereby improving the transmission quality and efficiency of the signal. The performance of the filter depends to a large extent on its impedance matching degree. When the impedance of the filter matches the impedance of the transmission line, the filter can better play its filtering role and effectively filter and suppress signals of specific frequencies. This helps to ensure the signal quality in the system and avoid the influence of interference and noise. Impedance matching also enhances the stability of the system. In high-frequency circuits, impedance mismatch causes signal oscillation and instability phenomena. By optimizing impedance matching, ensure that the signals in the system remain stable during transmission, thereby enhancing the overall performance and reliability of the system.

[0081] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, i.e., located in one place or distributed to multiple network units. Select some or all of the modules according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative effort.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. However, such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An electronic circuit having a transmission line type noise filter, characterized in that, Comprising: A frequency determination device for determining the operating frequency and voltage of an electronic circuit; A device determination device for selecting a microstrip line as a transmission line and optimizing a filter using a composite left-handed and right-handed transmission line and an open-circuit T-shaped structure; An impedance matching device, including an impedance measurement module, a selection method module, a device connection module, and an interference reduction module; the impedance measurement module is used to measure the input impedance and output impedance of the filter using a vector network analyzer and measure the characteristic impedance of the microstrip line; the selection method module is used to select a matching method for the impedance of the filter and the impedance of the transmission line according to the type of the filter, the operating frequency, and the impedance of the microstrip line; the device connection module is used to connect the filter and the microstrip line according to the matching method; the interference reduction module is used to adjust a common-mode choke and a Y-capacitor to reduce electromagnetic interference suppression of a computer motherboard; A matching measurement device for measuring the effect of the impedance matching device using a reflection coefficient and a voltage standing wave ratio, maximizing the signal transmission efficiency through the filter and reducing energy reflection; A software simulation device for performing circuit simulation on the matched filter and transmission line using simulation software and adjusting and optimizing the transmission line parameters and filter element values according to the simulation results.

2. The electronic circuit having a transmission line type noise filter according to claim 1, characterized in that, The device determination device includes: A transmission line selection module for using a microstrip line that meets a preset reflection coefficient standard as the transmission line of the filter and calculating the impedance of the required microstrip line; A composite left-handed and right-handed module for using an ultra-wideband filter with a composite left-handed and right-handed transmission line structure, adjusting the size of interdigital capacitors according to the power and frequency of a preset filter to achieve narrowband and broadband adjustment of the filter; An open-circuit T-shaped module for optimizing the frequency response of the filter by adjusting the arm length and width of the open-circuit T-shaped structure; simplifying the size of the filter by combining a microstrip line and a coplanar waveguide, and generating negative permittivity and negative permeability using a composite material; A line length determination module for determining the length of the transmission line according to a quarter wavelength of the filtering frequency.

3. The electronic circuit with a transmission line type noise filter according to claim 1, characterized in that, The calculation formula for the impedance of the microstrip line in the transmission line selection module is: Wherein, Z0 is the characteristic impedance, w is the line width of the microstrip line, t is the thickness of the metal, h is the dielectric thickness, and ɛ r is the relative dielectric constant of the dielectric.

4. The electronic circuit having a transmission line type noise filter according to claim 1, characterized in that, The selection method module includes: A small difference impedance unit for directly connecting the impedance of the filter and the impedance of the transmission line when the difference between the impedance data of the filter and the impedance of the transmission line is less than a preset value; A large difference impedance unit for adjusting the transmission parameters of the filter to optimize impedance matching and using a PI matching network to optimize the matching of the impedance of the filter and the impedance of the transmission line when the difference between the impedance data of the filter and the impedance of the transmission line is greater than a preset value.

5. The electronic circuit with a transmission line type noise filter according to claim 4, characterized in that, The large difference impedance module includes: A frequency determination sub-unit for determining the operating center frequency of the PI matching network according to the frequency characteristics of a computer motherboard; A device selection sub-unit for calculating the quality factor of the PI-type matching network, measuring the energy storage and loss of capacitors and inductors in the filter according to the quality factor, and selecting inductors and capacitors that meet the computer motherboard standard; A device calculation sub-unit for calculating the required inductor and capacitor values according to the impedance matching formula.

6. The electronic circuit having a transmission line type noise filter according to claim 5, characterized in that, In the device selection sub-unit, the calculation formula for the quality factor is: Wherein, R is the resistance, f0 is the resonance frequency, L is the capacitance, l is the conductor length, ρ is the resistivity, and A is the cross-sectional area of the conductor.

7. The electronic circuit with a transmission line type noise filter according to claim 1, characterized in that, The calculation device sub-unit calculates the parallel impedance according to the resistances and capacitances at the input end and the output end in the parallel impedance matching formula, calculates the series impedance according to the resistances and reactances at the input end and the output end in the series impedance matching formula, and calculates the level conversion impedance according to the conductor resistance, the angular frequency inductance, capacitance, and temperature of the signal in the level conversion impedance matching formula.

8. The electronic circuit having a transmission line type noise filter according to claim 7, wherein, The parallel impedance matching formula is expressed as: R1 and L1 are the resistance and capacitance at the input end, R2 and L2 are the resistance and capacitance at the output end, f is the frequency, and R and X are the matched resistance and reactance.

9. The electronic circuit with a transmission line type noise filter according to claim 7, characterized in that, The level conversion impedance matching formula is: Where Z is the total circuit impedance, l is the conductor length, ρ is the resistivity, A is the cross-sectional area of the conductor, ω is the angular frequency of the signal, L is the inductance in the circuit, C is the capacitance in the circuit, t is the temperature, α is the temperature coefficient of resistance, is the resistance value at 0 degrees Celsius.

10. The electronic circuit with a transmission line type noise filter according to claim 1, characterized in that, In the matching measurement device, the calculation formula for the reflection coefficient is: Where Z L is the impedance after change, and Z O is the impedance before change; The calculation formula for the voltage standing wave ratio is: Wherein, VSWR is the voltage standing wave ratio and K is the reflection coefficient.

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