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Accurate, Fast, Easy and Affordable Electromagnetic Signal Integrity Software for Physical Design of Interconnects for Communication Links |
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Frequently Asked Questions
Is Simbeor available for evaluation? Simbeor is available for 15-day evaluation. Go to Downloads/Software section and follow the instructions to download the installation module and to obtain the evaluation license. How much does Simbeor cost? Simbeor is advanced and yet the most competitively priced electromagnetic analyisis tool on the market. Click here to see the current US prices for different licensing options of Simbeor. What are the limitations of a static field solver? Why do I need an electromagnetic field solver? There are some effects that static and quasi-static tools do not take into account. Such effects can significantly affect the parameters of interconnects. For instance, inhomogeneous dielectrics cause dispersion of transmission line parameters at high frequencies (starting from 5-10 GHz for typical PCB applications). It is visible as changes in phase and group velocities with frequency and can not be accounted for with a static solution. Dispersion can cause considerable degradation of a digital signal in multi-gigabit channels. Effects of metal surface roughness and conductor surface plating are also not accounted for by static tools that can also significantly increase attenuation and degrade signal. Static solvers do not capture effects of current redistribution in planes and conductors when skin depth is comparable with thickness or width of the conductors. It takes place in typical PCB interconnects at frequencies from 10 MHz to 100 MHz and in different IC technologies at frequencies ranging from 1 GHz to 100 GHz. A magneto-quasi-static solver may be required to capture these effects in addition to electro-static one. To be characterized with a static solver, a cross-section of transmission line has to be much smaller than wavelength. In other words, static solvers do not account for delays in the cross-section of a transmission line and thus cannot be used to characterize meander delay lines for instance. Finally, all not well explored effects related to non-orthogonality of modes and modal transformations can not be captured with a static tool. It is uncertain how such phenomena can affect interconnect performance without the rigorous electromagnetic analysis. Technical presentations on transmission lines cover this subject in greater details. What's wrong with 2D electromagnetic field solvers available with some general-purpose 3D tools? These solvers are designed to support extraction of S-parameters in some 3D tools and usually do not have possibilities to extract frequency-dependent RLGC parameters of multiconductor lines. They do not compute characteristic impedance with 3D definition - the impedance definition closest to experimentally measured so far. In addition these tools usually do not have causal dielectric models and simulate metal with simplified surface impedance boundary conditions with incorrect low and mid-frequency asymptotes and without roughness. Why do not just use a general purpose 3D electromagnetic solver for multiconductor line analysis? General purpose 3D electromagnetic tools usually extract S-parameters of a segment of line in spatial domain. They do not directly extract parameters of multiconductor transmission lines that you can conveniently reuse as a model for segments with different lengths in a SPICE-type simulator. Per unit length parameters can be extracted from S-parameters of a line segment, but it is not a trivial task to say the least. In addition, meshing requirements for accurate analysis of multiconductor lines are prohibitive if you want to achieve practical accuracy especially in characteristic impedance. Tools with optimized performance for stratified geometries (planar 3D or 2.5D) provide much high accuracy for planar problems, but have some limitations too. Technical presentations on transmission lines cover this subject in greater details. What is the difference of Simbeor 3DML solver with existing 3D planar simulators? There are some fundamental limitations in the other 3D planar tools. Extraction of parameters of lossy lines is usually available only for one-strip and symmetrical two-strip transmission lines only. There is no multimode analysis of lossy multiconductor lines in general. Loss effects in strips and planes are usually simulated with the equivalent surface impedance boundary conditions that is only a high-frequency approximation. In addition, these tools are usually optimized for narrow-band problems with non-causal models for dielectrics that leads to poor accuracy of the reduced-order models derived for analysis of wideband circuits. Note, that problem approximation typical for so called 3D planar of 2.5D solvers is available as a special simulation option in our Simbeor 3DML solver. It provides fast and accurate solutions for structures with large trace width to thickness ratio. |
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