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PCB Tech

PCB Tech

PCB Tech

PCB Tech

Simulation of the performance of the tool software PCB
2021-09-14
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Author:Frank

Generally, the properties of the circuit board material have a lot to do with the performance of the final circuit board (PCB), especially at RF/microwave frequencies. The parameters of the circuit board material, such as dielectric constant (Dk), dissipation factor (Df), and even the thickness of the material will affect different transmission lines (such as: microstrip line, strip line, coplanar waveguide) in high-frequency circuits Performance. Fortunately, there is a simple and efficient tool software that can predict the performance of different high-frequency transmission lines and processed on different circuit board materials, which is the microwave impedance (MWI) calculation software provided by Rogers Corporation.

The software can be installed on any personal computer (PC) that can run the Microsoft Windows 10 operating system (OS), and it can also be run from the website. The latest version of the software, MWI-2019, uses closed equations and calculates the performance of a specific transmission line based on the differences in various parameters of the basic circuit board materials (such as Dk, thickness, and other material parameters). According to different material characteristics, the software can also calculate different performance and working parameters of the transmission line, including: characteristic impedance, loss and quality factor (Q), etc. The software allows users to select different boards from the circuit board material library and perform calculations based on various high-frequency transmission line technologies, including microstrip line, stripline, grounded coplanar waveguide (GCPW), edge-coupled microstrip, and edge-coupled strip Stripline (or differential pair stripline) and broadside coupled stripline.

The closed equation of the software can provide very accurate simulation, which is based on a large amount of test data on some transmission lines used. In most cases, the simulation results for a given circuit board material and a given transmission line technology are very consistent with the actual measurement results of the actual processed transmission line on the vector network analyzer (VNA). Especially for some of the most commonly used transmission line types, such as: microstrip, stripline and grounded coplanar waveguide (GCPW).

Fast running speed

pcb board

The tool software MWI-2019 has many advantages. In addition to being free of charge and being able to achieve high precision on ordinary PCs, one of its notable features is its efficient operating speed. When simulating transmission lines of different circuit board materials, if other commercial three-dimensional full-wave electromagnetic (EM) field simulation software is used, even with the most advanced and latest PC, the simulation may take several hours. However, the original intention of the MWI-2019 software was to be able to run quickly and efficiently on a regular PC. Basically, after setting the relevant parameters, as long as you press the "Calculate" button of the software, the software can give accurate simulation results almost immediately.

Of course, EM field simulation software can usually provide three-dimensional full-wave calculations, which can provide much higher accuracy than convenient free software such as MWI-2019, at the cost of a longer simulation time. But MWI-2019 is not intended to replace EM field simulation software. MWI-2019 software can provide very useful and reliable reference results. Its fast calculation advantage can help circuit design engineers to correctly and quickly select the DK value, thickness and thickness of the circuit board material when designing different transmission line circuits in a very short time. Determine the indicators of other circuit board materials. For a given high-frequency transmission line technology and circuit design, the simulation speed of MWI-2019 enables engineers to find the best circuit parameters among a large number of circuit board materials. When higher simulation accuracy is required and sufficient calculation time is available, engineers can use EM field simulation software to seek more refined simulation results at any time.

MWI-2019 software can quickly compare the performance of transmission lines on different circuit board materials, allowing users to compare and choose between multiple materials. For example: How is the transmission line loss of the microstrip circuit affected by different circuit board materials at different frequencies? When changing circuit board materials, the software will use the closest standard thickness of each material and the best copper foil type for each material to simplify the comparison. If the user is interested in analyzing and comparing some specific parameters of the material (such as Dk and thickness), the software can also modify these default standard values to allow the user to customize the settings.

Reliable calculation accuracy

Although the simulation speed is fast, MWI-2019 can still provide very accurate simulation results through the specific closed equation and model optimization of the transmission line. The user can use the default standard material parameters built in the software, or by fine-tuning the circuit board material parameters (including the design Dk, thickness, and even the definition of copper wires) to simulate the transmission line circuit and materials (MWI-2019 contains a variety of copper Surface roughness model). Before performing transmission line analysis and calculation on circuit board materials, the software allows users to modify the default default values and enter their own values to perform custom calculations on the frequencies of interest, so as to quickly explore how different transmission lines vary with materials and frequencies. The choices vary.

When the user selects the pcb circuit board material from MWI-2019, as well as the thickness of the circuit board material, and the working frequency, the MWI-2019 software finds the specific specific Dk from a large number of material parameter databases (according to the thickness of the material or the z-axis) established These Dk values are obtained from actual measurements based on the frequency of different materials. The database of the Dk value of each material varies with frequency is established based on the actual measurement of hundreds of circuits tested at different frequencies and different thicknesses of circuit board materials. These design Dk values can also be used in a wide frequency range: the latest version of the software design Dk value is suitable for frequencies from 100 MHz to 110 GHz, and supports 60 GHz and higher. For example: emerging 5G millimeter wave applications, cellular communication networks, automotive radar security systems, etc. Compared with the earlier version of the software, MWI-2019 also contains more options for circuit board materials, as well as a large number of corresponding design Dk databases and transmission line models that have been optimized for materials.

The two most widely used high-frequency transmission lines, namely microstrip line and strip line, are also the two most accurate models in MWI-2019. According to the simulation results provided by the software, the actual measurement value of the transmission line processed on the actual circuit board material is almost the same as the simulation value. For other types of transmission lines, such as edge-coupled microstrip and edge-coupled stripline, although there is no large amount of measurement data to enhance the repeatability and accuracy of the simulation, the model and the closed equation also provide very accurate results.