LTCC (Low Temperature Co-Fired Ceramic) Ka-band millimeter wave broadside coupling band-pass filter and simulation optimization method thereof

Abstract

The invention discloses an LTCC Ka-band millimeter wave broadside coupling band-pass filter and a simulation optimization method thereof, relates to the field of filter simulation, and remarkably improves the performance of the LTCC Ka-band millimeter wave band-pass filter through an integrated thermal management strategy and accurate parasitic parameter control in combination with a multi-objective optimization algorithm. The thermal stability and long-term reliability under high-frequency operation are ensured, meanwhile, the design process is optimized, and high precision and high efficiency of filter design are achieved.

Description

Technical Field

[0001] The invention relates to the field of filter simulation, in particular to a LTCC Ka-band millimeter-wave broadside-coupled bandpass filter and a simulation optimization method thereof. Background Art

[0002] With the rapid development of wireless communication technology, especially in the Ka-band millimeter wave field, the demand for high-performance signal processing components is growing. LTCC (low temperature co-fired ceramic) technology has become one of the preferred technologies for realizing millimeter wave bandpass filters due to its excellent electrical performance, good thermal stability and flexible design freedom. Filters manufactured using LTCC technology can meet the needs of millimeter wave bands for high-performance filters, including but not limited to low insertion loss, high selectivity and wide bandwidth characteristics.

[0003] LTCC technology allows the stacking of multiple layers of dielectric substrates and conductor layers, and a compact and high-performance filter structure is achieved through a precise co-firing process. In the design of Ka-band millimeter-wave filters, a multi-layer LTCC dielectric substrate is usually used, with copper conductor layers printed on the top and bottom layers, and resonators are arranged on the copper conductor layers. The resonators interact with the conductor layers through edge coupling to achieve the required filtering function. In addition, the application of high-frequency electromagnetic field simulation tools enables designers to simulate the electromagnetic field distribution of the filter structure during the design stage, predict the filter performance, and thus optimize the filter design.

[0004] Although LTCC technology has shown great potential in millimeter wave filter design, existing technologies still face some challenges in realizing Ka-band millimeter wave bandpass filters. One of the main problems is the difficulty in controlling parasitic parameters, including parasitic capacitance and parasitic inductance, which can seriously affect the performance of the filter, such as resonant frequency shift and reduced selectivity. In addition, the thermal effect generated under high-frequency operation is also a key issue. If the heat cannot be effectively dissipated, the filter performance will be degraded or even damaged.

[0005] In the existing technology, the calculation and optimization of parasitic parameters usually lacks accuracy and systematicity, resulting in the failure to fully consider the impact of these parameters on filter performance during the design process. At the same time, the evaluation of thermal effects and thermal management strategies are often considered only in the later stages of the design, rather than being an integrated part in parallel with the filter design. Summary of the invention

[0006] In view of the defects of the prior art, the present invention proposes a LTCC Ka-band millimeter-wave wide-side coupled bandpass filter and a simulation optimization method thereof, and solves the accuracy and systematic problems of the filter in the prior art by combining high-frequency simulation with a multi-objective optimization algorithm.

[0007] Among them, the LTCC Ka-band millimeter-wave broadside coupled bandpass filter, the filter is formed by a three-layer LTCC dielectric substrate, the top layer and the bottom layer of the three-layer LTCC dielectric substrate are respectively printed with a copper conductor layer, the copper conductor layer is provided with a resonator, and the resonator acts with the conductor layer through edge coupling;

[0008] The filter includes a high-frequency electromagnetic field simulation unit, and the high-frequency electromagnetic field simulation tool is used to simulate according to the initial parameters of the resonator, simulate the electromagnetic field distribution of the filter structure in the Ka band, and calculate the parasitic parameters according to the simulation results and evaluate the thermal effects generated under high-frequency operation;

[0009] The filter comprises an optimization unit, which is used to iteratively adjust the parasitic parameters of the resonator and the conductor layer by minimizing the influence of the parasitic parameters on the resonance frequency according to the calculated parasitic parameters through a multi-objective optimization algorithm.

[0010] Furthermore, the high-frequency electromagnetic field simulation unit includes:

[0011] Parasitic parameter calculation module, used to calculate parasitic capacitance and parasitic inductance between conductor layers;

[0012] High-frequency simulation module, used to simulate and analyze the filter structure;

[0013] The thermal effect analysis module is used to establish a filter thermal model based on the structural characteristics of the filter, and predict hot spots and temperature distribution based on the thermal analysis results of the filter under the expected high-power signal by the high-frequency simulation module.

[0014] Furthermore, in the parasitic parameter calculation module, the calculation principle of the parasitic capacitance is:

[0015]

[0016] Among them, the C p represents the parasitic capacitance, the λ 0 represents the wavelength in free space, the ε r represents the relative permittivity of the medium, A represents the area of ​​the conductor layer, and d represents the thickness of the dielectric layer.

[0017] Furthermore, in the parasitic parameter calculation module, the calculation principle of parasitic inductance is:

[0018]

[0019] Among them, the L p represents parasitic inductance, ω represents angular frequency, μ rrepresents the magnetic permeability of the dielectric material relative to vacuum, N represents the number of turns of the microstrip line, l represents the length of the conductor, h represents the height of the dielectric substrate, t represents the thickness of the conductor, σ represents the electrical conductivity of the conductor, and ρ represents the resistivity of the conductor.

[0020] Furthermore, in the optimization unit, the multi-objective optimization algorithm minimizes the influence of parasitic parameters on the resonant frequency. The specific principle is: by using a particle swarm optimization algorithm based on frequency selectivity, the parasitic parameters are minimized:

[0021]

[0022] Wherein, the Fitness Function represents the fitness function, which is used to evaluate the performance of the filter design in the particle swarm optimization algorithm, and the f r represents the actual resonant frequency, the f r，ideal represents the desired frequency value, Q represents the actual quality factor, and Q ideal Indicates the quality factor value that is expected to be achieved.

[0023] Furthermore, a simulation optimization method for a LTCC Ka-band millimeter-wave broadside coupled bandpass filter is provided, which is implemented based on the LTCC Ka-band millimeter-wave broadside coupled bandpass filter described in any one of the above items, and comprises the following steps:

[0024] S1. Set the filter performance indicators, including center frequency, bandwidth, insertion loss and suppression, and preliminarily design the size and shape of the resonator based on the requirements of the Ka band;

[0025] S2. simulate the electromagnetic field distribution of the filter structure in the Ka band according to the initial parameters of the resonator, calculate the parasitic parameters and evaluate the thermal effects generated under high-frequency operation according to the simulation results;

[0026] S3. According to the calculated parasitic parameters, the influence of the parasitic parameters on the resonant frequency is minimized by a multi-objective optimization algorithm, and the parasitic parameters of the resonator and the conductor layer are iteratively adjusted.

[0027] Furthermore, the step S2 specifically includes the following sub-steps:

[0028] S201. Calculate parasitic capacitance and parasitic inductance between conductor layers;

[0029] S202. Perform simulation analysis on the filter structure;

[0030] S203. Establish a thermal model of the filter based on the structural characteristics of the filter, and predict hot spots and temperature distribution based on the thermal analysis results of the filter under the expected high-power signal by the high-frequency simulation module.

[0031] Furthermore, in step S201, the calculation principle of the parasitic capacitance is:

[0032]

[0033] Among them, the C p represents the parasitic capacitance, the λ 0 represents the wavelength in free space, the ε r represents the relative permittivity of the medium, A represents the area of ​​the conductor layer, and d represents the thickness of the dielectric layer.

[0034] Furthermore, in step S201, the calculation principle of the parasitic inductance is:

[0035]

[0036] Among them, the L p represents parasitic inductance, ω represents angular frequency, μ r represents the magnetic permeability of the dielectric material relative to vacuum, N represents the number of turns of the microstrip line, l represents the length of the conductor, h represents the height of the dielectric substrate, t represents the thickness of the conductor, σ represents the electrical conductivity of the conductor, and ρ represents the resistivity of the conductor.

[0037] Furthermore, in step S3, the specific principle of the multi-objective optimization algorithm to minimize the influence of parasitic parameters on the resonant frequency is: by using a particle swarm optimization algorithm based on frequency selectivity, the parasitic parameters are minimized:

[0038]

[0039] Wherein, the Fitness Function represents the fitness function, which is used to evaluate the performance of the filter design in the particle swarm optimization algorithm, and the f r represents the actual resonant frequency, the f r，ideal represents the desired frequency value, Q represents the actual quality factor, and Q ideal Indicates the quality factor value that is expected to be achieved.

[0040] The beneficial effects of the invention are:

[0041] The present invention significantly improves the performance of LTCC Ka-band millimeter-wave bandpass filters through an integrated thermal management strategy and precise parasitic parameter control combined with a multi-objective optimization algorithm, ensuring thermal stability and long-term reliability under high-frequency operation, while optimizing the design process to achieve high precision and high efficiency in filter design. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1A method flow chart of a method for simulating and optimizing a LTCC Ka-band millimeter-wave broadside-coupled bandpass filter provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention. It should be noted that relational terms such as the terms "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0046] Moreover, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a list of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus. In the absence of more restrictions, an element defined by the phrase "comprises a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0047] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0048] Among them, the LTCC Ka-band millimeter-wave broadside coupled bandpass filter, the filter is formed by a three-layer LTCC dielectric substrate, the top layer and the bottom layer of the three-layer LTCC dielectric substrate are respectively printed with a copper conductor layer, the copper conductor layer is provided with a resonator, and the resonator acts with the conductor layer through edge coupling;

[0049] The filter includes a high-frequency electromagnetic field simulation unit, and the high-frequency electromagnetic field simulation tool is used to simulate according to the initial parameters of the resonator, simulate the electromagnetic field distribution of the filter structure in the Ka band, and calculate the parasitic parameters according to the simulation results and evaluate the thermal effects generated under high-frequency operation;

[0050] The filter comprises an optimization unit, which is used to iteratively adjust the parasitic parameters of the resonator and the conductor layer by minimizing the influence of the parasitic parameters on the resonance frequency according to the calculated parasitic parameters through a multi-objective optimization algorithm.

[0051] Furthermore, the high-frequency electromagnetic field simulation unit includes:

[0052] Parasitic parameter calculation module, used to calculate parasitic capacitance and parasitic inductance between conductor layers;

[0053] High-frequency simulation module, used to simulate and analyze the filter structure;

[0054] The thermal effect analysis module is used to establish a filter thermal model based on the structural characteristics of the filter, and predict hot spots and temperature distribution based on the thermal analysis results of the filter under the expected high-power signal by the high-frequency simulation module.

[0055] Furthermore, in the parasitic parameter calculation module, the calculation principle of the parasitic capacitance is:

[0056]

[0057] Among them, the C p represents the parasitic capacitance, the λ 0 represents the wavelength in free space, the ε r represents the relative permittivity of the medium, A represents the area of ​​the conductor layer, and d represents the thickness of the dielectric layer.

[0058] Furthermore, in the parasitic parameter calculation module, the calculation principle of parasitic inductance is:

[0059]

[0060] Among them, the L p represents parasitic inductance, ω represents angular frequency, μ r represents the magnetic permeability of the dielectric material relative to vacuum, N represents the number of turns of the conductor, l represents the length of the conductor, h represents the height of the dielectric substrate, t represents the thickness of the conductor, σ represents the electrical conductivity of the conductor, and ρ represents the resistivity of the conductor.

[0061] Furthermore, in the optimization unit, the multi-objective optimization algorithm minimizes the influence of parasitic parameters on the resonant frequency. The specific principle is: by using a particle swarm optimization algorithm based on frequency selectivity, the parasitic parameters are minimized:

[0062]

[0063] Wherein, the Fitness Function represents the fitness function, which is used to evaluate the performance of the filter design in the particle swarm optimization algorithm, and the f r represents the actual resonant frequency, the f r，idenal represents the desired frequency value, Q represents the actual quality factor, and Q ideal Indicates the quality factor value that is expected to be achieved.

[0064] Specifically, the high-frequency electromagnetic field simulation tool analyzes the electromagnetic field distribution of the filter structure in the Ka band, and needs to calculate the resonant frequency and quality factor, namely: and Among them, the f r represents the resonant frequency, c represents the speed of light in a vacuum, s represents the physical size of the resonator, Δf represents the bandwidth of the resonator, and Q represents the quality factor.

[0065] Furthermore, as a preferred specific implementation scheme of this embodiment, a high-performance LTCC bandpass filter design for the Ka band (26.5-40 GHz) is proposed, and the specific principle process is as follows:

[0066] Use LTCC dielectric materials, dielectric materials with high dielectric constant and low loss tangent to support high-frequency signals in the Ka band;

[0067] For the above three-layer structure, the thickness of each dielectric substrate is 100 microns to achieve the required electrical length and physical size, while maintaining the symmetry of the structure and reducing parasitic effects; wherein, a copper conductor layer is printed on the first (top) and third (bottom) dielectric substrates with a thickness of 20 microns to achieve the required conductivity and thermal stability; resonators are designed on the top and bottom conductor layers, and the second layer is used as an isolation medium to avoid direct electromagnetic coupling between the top and bottom layers, while maintaining a precise gap between the resonators to control parasitic capacitance;

[0068] Calculate and optimize parasitic capacitance and parasitic inductance. Specifically, for the capacitance of the microstrip line, the calculation formula is:

[0069]

[0070] Among them, the μ 0 represents the magnetic permeability of vacuum, the ε 0Represents the permittivity of vacuum. For microstrip line inductance, the influence of dielectric layer thickness on capacitance is more direct and significant, so the dielectric layer thickness d is directly used as the determining factor for capacitance calculation;

[0071] Implement differential signal paths on the top and bottom conductor layers, and reduce common-mode parasitic effects through symmetrical layout;

[0072] Evaluate the electromagnetic compatibility of the filter using 3D electromagnetic simulation software, taking into account the thermal effects of Ka-band high-power signals;

[0073] A multi-objective optimization algorithm, specifically particle swarm optimization (PSO), is used to optimize the filter design for the performance requirements of the Ka-band.

[0074] The conductor layer is screen-printed with a conductive paste (such as copper paste) to form a conductor pattern, and the vertical integration capability in the LTCC technology is utilized to achieve electrical connection between the conductor layers of different dielectric layers through metallized via holes; the dielectric substrates printed with the conductor patterns are stacked in a designed order, and laminated and co-fired at high temperature; the resonator interacts with the adjacent conductor layer through edge coupling to achieve the desired filtering performance.

[0075] Further, as a preferred specific implementation scheme of the above embodiment, in step S2, parasitic parameters are calculated according to simulation results and thermal effects generated under high-frequency operation are evaluated. The specific implementation principle and optimization process are as follows:

[0076] According to Fourier's law, the heat conduction equation is established for the LTCC dielectric substrate and conductor layer. A thermal model is established, wherein q represents the heat conduction equation, k represents the thermal conductivity of the LTCC material, and represents the temperature gradient along the thickness direction;

[0077] Consider the thermal effects of Ka-band high-power signals, including natural convection and radiation effects, where convection is described by Newton's cooling law: q conv =h(T surf -T amb ), wherein the q conv represents the heat flux caused by convection, h represents the convection heat transfer coefficient, T surf represents the filter surface temperature, the T amb Indicates the ambient temperature;

[0078] Optimize thermal resistance and thermal capacitance by adjusting the thickness of the LTCC layer; perform thermal field simulation on the entire LTCC filter structure and minimize the maximum junction temperature or thermal resistance of the filter through the objective function: Objective Function = w 1(T max -T limit ) 2 +w 2 (R th -R yh，ideal ) 2 , where the Objective Function represents the objective function, and the w 1 and w 2 Represents the weight coefficient of temperature and thermal resistance, the T max represents the maximum junction temperature, the T limit Indicates the temperature limit, the R th represents the actual thermal resistance, the R yh，ideal represents the ideal thermal resistance;

[0079] Adjust the filter structure design according to the output thermal resistance and thermal capacitance parameters.

[0080] Further, a simulation optimization method for a LTCC Ka-band millimeter-wave broadside coupled bandpass filter is provided, which is based on the LTCC Ka-band millimeter-wave broadside coupled bandpass filter described in any one of the above items, such as Figure 1 , including the following steps:

[0081] S1. Set the filter performance indicators, including center frequency, bandwidth, insertion loss and suppression, and preliminarily design the size and shape of the resonator based on the requirements of the Ka band;

[0082] S2. simulate the electromagnetic field distribution of the filter structure in the Ka band according to the initial parameters of the resonator, calculate the parasitic parameters and evaluate the thermal effects generated under high-frequency operation according to the simulation results;

[0083] S3. According to the calculated parasitic parameters, the influence of the parasitic parameters on the resonant frequency is minimized by a multi-objective optimization algorithm, and the parasitic parameters of the resonator and the conductor layer are iteratively adjusted.

[0084] Furthermore, the step S2 specifically includes the following sub-steps:

[0085] S201. Calculate parasitic capacitance and parasitic inductance between conductor layers;

[0086] S202. Perform simulation analysis on the filter structure;

[0087] S203. Establish a thermal model of the filter based on the structural characteristics of the filter, and predict hot spots and temperature distribution based on the thermal analysis results of the filter under the expected high-power signal by the high-frequency simulation module.

[0088] Furthermore, in step S201, the calculation principle of the parasitic capacitance is:

[0089]

[0090] Among them, the C p represents the parasitic capacitance, the λ 0 represents the wavelength in free space, the ε r represents the relative permittivity of the medium, A represents the area of ​​the conductor layer, and d represents the thickness of the dielectric layer.

[0091] Furthermore, in step S201, the calculation principle of the parasitic inductance is:

[0092]

[0093] Among them, the L p represents parasitic inductance, ω represents angular frequency, μ r represents the magnetic permeability of the dielectric material relative to vacuum, N represents the number of turns of the microstrip line, l represents the length of the conductor, h represents the height of the dielectric substrate, t represents the thickness of the conductor, σ represents the electrical conductivity of the conductor, and ρ represents the resistivity of the conductor.

[0094] Furthermore, in step S3, the specific principle of the multi-objective optimization algorithm to minimize the influence of parasitic parameters on the resonant frequency is: by using a particle swarm optimization algorithm based on frequency selectivity, the parasitic parameters are minimized:

[0095]

[0096] Wherein, the Fitness Function represents the fitness function, which is used to evaluate the performance of the filter design in the particle swarm optimization algorithm, and the f r represents the actual resonant frequency, the f r，ideal represents the desired frequency value, Q represents the actual quality factor, and Q ideal Indicates the quality factor value that is expected to be achieved.

[0097] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. An LTCC Ka-band millimeter-wave broadside coupled bandpass filter, the filter being constructed by a three-layer LTCC dielectric substrate, a copper conductor layer being printed on the top layer and the bottom layer of the three-layer LTCC dielectric substrate, a resonator being arranged on the copper conductor layer, and the resonator acting on the conductor layer through edge coupling; Features: The filter includes a high-frequency electromagnetic field simulation unit, and the high-frequency electromagnetic field simulation tool is used to simulate according to the initial parameters of the resonator, simulate the electromagnetic field distribution of the filter structure in the Ka band, and calculate the parasitic parameters according to the simulation results and evaluate the thermal effects generated under high-frequency operation; The filter comprises an optimization unit, which is used to iteratively adjust the parasitic parameters of the resonator and the conductor layer by minimizing the influence of the parasitic parameters on the resonance frequency according to the calculated parasitic parameters through a multi-objective optimization algorithm.

2. The LTCC Ka-band millimeter-wave broadside coupled bandpass filter according to claim 1, characterized in that: The high-frequency electromagnetic field simulation unit comprises: Parasitic parameter calculation module, used to calculate parasitic capacitance and parasitic inductance between conductor layers; High-frequency simulation module, used to simulate and analyze the filter structure; The thermal effect analysis module is used to establish a filter thermal model based on the structural characteristics of the filter, and predict hot spots and temperature distribution based on the thermal analysis results of the filter under the expected high-power signal by the high-frequency simulation module.

3. The LTCC Ka-band millimeter-wave broadside coupled bandpass filter according to claim 2, characterized in that: In the parasitic parameter calculation module, the calculation principle of parasitic capacitance is: Among them, the C p represents the parasitic capacitance, λ0 represents the wavelength in free space, and ε r represents the relative permittivity of the medium, A represents the area of ​​the conductor layer, and d represents the thickness of the dielectric layer.

4. The LTCC Ka-band millimeter-wave broadside coupled bandpass filter according to claim 2, characterized in that: In the parasitic parameter calculation module, the calculation principle of parasitic inductance is: Among them, the L p represents parasitic inductance, ω represents angular frequency, μ r represents the magnetic permeability of the dielectric material relative to vacuum, N represents the number of turns of the microstrip line, l represents the length of the conductor, h represents the height of the dielectric substrate, t represents the thickness of the conductor, σ represents the electrical conductivity of the conductor, and ρ represents the resistivity of the conductor.

5. The LTCC Ka-band millimeter-wave broadside coupled bandpass filter according to claim 1, characterized in that: In the optimization unit, the multi-objective optimization algorithm minimizes the influence of parasitic parameters on the resonant frequency. The specific principle is: minimize the parasitic parameters by using a particle swarm optimization algorithm based on frequency selectivity: Wherein, the Fitness Function represents the fitness function, which is used to evaluate the performance of the filter design in the particle swarm optimization algorithm, and the f r represents the actual resonant frequency, the f r,ideal represents the desired frequency value, Q represents the actual quality factor, and Q ideal Indicates the quality factor value that is expected to be achieved.

6. A simulation optimization method for a LTCC Ka-band millimeter-wave broadside coupled bandpass filter, the method being implemented based on the LTCC Ka-band millimeter-wave broadside coupled bandpass filter according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Set the filter performance indicators, including center frequency, bandwidth, insertion loss and suppression, and preliminarily design the size and shape of the resonator based on the requirements of the Ka band; S2. simulate the electromagnetic field distribution of the filter structure in the Ka band according to the initial parameters of the resonator, calculate the parasitic parameters and evaluate the thermal effects generated under high-frequency operation according to the simulation results; S3. According to the calculated parasitic parameters, the influence of the parasitic parameters on the resonant frequency is minimized by a multi-objective optimization algorithm, and the parasitic parameters of the resonator and the conductor layer are iteratively adjusted.

7. The LTCC Ka-band millimeter-wave broadside coupled bandpass filter simulation optimization method as claimed in claim 6, characterized in that: The step S2 specifically includes the following sub-steps: S201. Calculate parasitic capacitance and parasitic inductance between conductor layers; S202. Perform simulation analysis on the filter structure; S203. Establish a thermal model of the filter based on the structural characteristics of the filter, and predict hot spots and temperature distribution based on the thermal analysis results of the filter under expected high-power signals through high-frequency simulation.

8. The LTCC Ka-band millimeter-wave broadside coupled bandpass filter simulation optimization method as claimed in claim 7, characterized in that: In step S201, the calculation principle of parasitic capacitance is: Among them, the C p represents the parasitic capacitance, λ0 represents the wavelength in free space, and ε r represents the relative permittivity of the medium, A represents the area of ​​the conductor layer, and d represents the thickness of the dielectric layer.

9. The LTCC Ka-band millimeter-wave broadside coupled bandpass filter simulation optimization method as claimed in claim 7, characterized in that: In step S201, the calculation principle of parasitic inductance is: Among them, the L p represents parasitic inductance, ω represents angular frequency, μ r represents the magnetic permeability of the dielectric material relative to vacuum, N represents the number of turns of the microstrip line, l represents the length of the conductor, h represents the height of the dielectric substrate, t represents the thickness of the conductor, σ represents the electrical conductivity of the conductor, and ρ represents the resistivity of the conductor.

10. The LTCC Ka-band millimeter-wave broadside coupled bandpass filter simulation optimization method as claimed in claim 6, characterized in that: In step S3, the multi-objective optimization algorithm minimizes the influence of parasitic parameters on the resonant frequency. The specific principle is: minimize the parasitic parameters by using a frequency-selective particle swarm optimization algorithm: Wherein, the Fitness Function represents the fitness function, which is used to evaluate the performance of the filter design in the particle swarm optimization algorithm, and the f r represents the actual resonant frequency, the f r，ideal represents the desired frequency value, Q represents the actual quality factor, and Q idedl Indicates the quality factor value that is expected to be achieved.

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