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Today’s PCB design engineers have more layout and analysis tools at their disposal than ever before. Over the years we’ve seen layout tools become more automated, rules-driven, and more integrated. Now we even have integration between design tools from different vendors and ranging across domains, starting with basic circuit design, and spanning up to PLM and ERP integration. It really is a great time to be a designer.
But there is one area that continues to be a bit disconnected from the rest of the design process: simulation and analysis. Those of you who know me will know that I love simulation, and I love analyzing interconnects to death. If you’re like me, then you probably prefer to do all this by hand. If not, there are plenty of electronics and electromagnetics simulation software suites to help you along the way.
The problem with today’s simulation software options is not their capabilities; if you shop around enough, you’ll find a simulation for just about anything. The problem with the industry-standard simulation tools lies in where they fit into the standard PCB design workflow, as well as the user experience. Simulation software used in electronics and PCB design generally falls into one of the following categories.
- Circuit or schematic simulation tools (e.g., SPICE)
- 2D interconnect simulators implementing BEM or MoM
- Electromagnetic field solvers implementing FDTD, FEM/FEA, or a similar numerical method
All engineers and designers are probably familiar with SPICE; if you’re not, you should be. I consider the ability to run a SPICE simulation a mandatory skill for any PCB designer. Advanced applications will go far beyond SPICE and should use some level of simulation to verify signal integrity, channel compliance, and EMI.
Not all PCB design applications include a 2D interconnect simulator that can return impedance, reflections, crosstalk, and return path tracking in a PCB layout. Applications that do include these simulators will not have it running in the online DRC engine. For everyone else, there are both free and paid calculator applications that will give you a rough estimate of crosstalk and reflections.
Within the standard workflow, 2D simulators can work as a verification tool for interconnects once layout and routing are completed. In most of these tools, the user interface is sub-optimal. These are not point-and-click simulation tools that operate like DRCs. Some configuration is needed, and you need to know some inputs with high certainty to gain meaningful results. For this reason, these simulators are not often accessed while the design is being created; you’ll find that users wait until the design is near completion to use these if they are used at all.
To read this entire article, which appeared in the July 2022 issue of Design007 Magazine, click here.