# The Types and Advantages of Using EM Simulation in PCB Design

From basketball to football to soccer, to archery, to solving algebraic equations, the advice is always the same: “Practice makes perfect.” This is the universal spoken and unspoken rule that we all tend to abide. If you ask any professional, regardless of their profession, how did you become so proficient? Their collective answer will always lead back to practice or repetition.

Well, the ultimate form of practice in the field of PCB design and electronics as a whole is a simulation. Every design should start and end with simulation before attempting any actual fabrication of said design.

That last statement is no less true when referring to electromagnetic (EM) design analysis. With the aid of simulation, electromagnetic analysis in the design flow of electronic circuits is essential to avoiding expensive reworks. Furthermore, as operating frequencies increase, you cannot make an accurate prediction of PCB performance based solely on circuit performance. Achieving precise designs requires the consideration of physical properties, multiple technologies, interactions, and packaging that only EM modeling and simulation can provide.

## What is Electromagnetic Simulation?

Electromagnetic simulation is a modern technology for simulating electromagnetic devices, based on different simulation methods. In the field of electronics today, EM simulation is becoming the tool more, and more designers and engineers are using to replace costly prototyping.

Furthermore, since EM simulation software is a newer technology, it is not as popular as say structural analysis simulation software. Therefore, at this current time, there are fewer commercially available software packages for EM simulations in comparison to the mechanical analysis tools available today.

Overall, there are two divisions or groups in which electromagnetic simulation software packages are divided: circuit simulators and field simulators. The software for electromagnetic field simulation can also be categorized into subsets according to frequency criteria.

Low-frequency: static electric and magnetic field simulation software

High-frequency: electromagnetic software

The more popular methods for field simulations now are finite elements, boundary elements, or finite differences.

## How to Choose a 3D Electromagnetic Simulation Software

When choosing an EM simulator, you must first decide if you want it integrated into your advanced design system to co-simulate with circuit components, or as a standalone 3D EM design and simulation tool.

Integrated EM Simulation is ideal for RF circuit designers of RF Modules, MMICs, RFICs, and RF Boards. More specifically, for those who routinely perform EM-circuit co-simulation to accurately account for the parasitic effects of physical interconnects on their circuits. Also, integrated EM simulation affords designers the ability to optimize and tune their distributed circuit components with physical interconnects.

Now, a standalone 3D EM design and simulation software enable the accurate analysis of 3D physical models and parameterized 3D components such as RF shields, connectors, and packages.

Working through difficult RF designs can demand a field solver.

## The Comparison of Integrated and Standalone Electromagnetic Simulation

Today’s electronics are continually aiming for more prodigious integration, better performance, and more portability. Therefore, in response, designers and engineers are using an increasing amount of design software (simulation) to ensure precision, compatibility, and standards conformity. Furthermore, one of these tools is EM simulation software, and as I mentioned earlier, it comes in two distinct applications: integrated and standalone. Although advancements in the field of electronics are a constant pursuit that welcomes all devices, it comes with a side-effect; the increasing need for analysis tool advancements.

In general, some criteria warrant the use of one application standard instead of the other, but there are also hidden costs as well. The costliest difference between the use of integrated EM simulation software and standalone is time. In summary, standalone is a more time consuming and overall expensive approach to EM simulation.

For example, here are the typical steps necessary to implement standalone EM simulation.

• Draw the layout geometry

• Assign materials

• Export the graphic database system (GDSII) file format

• Import the GDSII (Geometrical Database for Information Interchange) file into the nonintegrated EM simulation tool

• Reassign material information

• Export port locations to a mask file

• Run the custom program to create a script file

• Run the script file to auto-generate ports in EM tool

• Run EM simulation for S-parameters (depending on simulation)

• Import S-parameters from EM simulation tool back into the circuit simulator

• Reconnect ports

• Co-simulate and verify performance (depending on requirements)

## What to Expect from an Electromagnetic Simulation Software

Once you parse the details of the applicational properties of EM simulation, it is a more accurate and logical conclusion that the ideal EM simulation solution incorporates the best aspects of both the integrated and nonintegrated solutions.

For example, Cadence Clarity 3D Solver, which is a 3D electromagnetic simulation software tool for designing critical interconnects for PCBs, IC packages, and systems on IC (SoIC) designs. The Clarity 3D Solver lets you tackle the most complex electromagnetic challenges when designing systems for 5G, automotive, high-performance computing (HPC), and machine learning applications with gold-standard accuracy.

There are definite advantages to both aspects of EM simulation, but combined, you receive an aspect of EM simulation that can meet the requirements of nearly every electromagnetic design analysis need. Furthermore, there is no debate on the importance of simulation, especially with the increasing demands of our ever-advancing electronic devices. In today’s electronics driven world, it is no longer just a requirement; it’s critical.

Planning out difficult designs is increasingly less of a purely human challenge to tackle.

Electromagnetic simulation falls under the purview as all simulation software today does; it is a critical requirement. There is no foreseeable end to the increase in the demand for faster, better performing, and more connected devices. Therefore, we, as engineers and designers, must also pursue better, more efficient, and accurate solutions to meet those demands. The saying still goes, “Practice makes perfect,” and the ultimate form of practice in PCB design is simulation; that includes EM.

Work towards a comprehensive EM simulation solution for all your design needs with Cadence’s suite of design and analysis tools. To work toward EM simulation, analysis, and layout solutions, start with Allegro PCB Designer for your current and future PCB designs.