6 Qualities to Look for in Electromagnetic Interference Software

There are two considerations for electromagnetic compatibility:

– Self-compatibility
– EMC test compliance

Self-compatibility fundamentally means that circuit operation in one part of the system doesn’t interfere with circuit operation in another part of the system. The system is self-compatible.
On the other hand, EMI test compliance is accomplished when a product or system has passed required electromagnetic interference tests.
While self-compatibility can be an issue for some electronic designs, it is generally less pervasive and less challenging than passing the gauntlet of mandated EMI tests.

Electromagnetic interference is multi-faceted.

Most electronic equipment is subjected to four test categories:

> Conducted emissions
> Radiated emissions
> Conducted susceptibility
> Radiated susceptibility

Each category may contain several different EMI tests. For example, conducted susceptibility tests may include audio frequency, radio frequency, and transient tests applied in a variety of ways to each electrical cable in the system, including the input power cable.
Once a device has passed its EMI tests, the likelihood of real-world interference problems is greatly reduced. That’s why EMI tests are required.

How do I design my system so that it passes its EMI tests?

For an engineer working on a new product, the goal is to pass the tests at the EMI laboratory.
Passing EMI tests is all about prevention. Find the balance between enough EMI controls into the design to pass the tests, without over-designing and driving up the cost and complexity of the product.
At about $2000 a day, EMI lab costs can quickly add up. A single EMI test failure can be devastating. Particularly if the problem is difficult to troubleshoot or requires partial redesign and the product. Retest costs alone can be significant.
Electromagnetic Interference Software is essential for minimizing design iterations.

Look for these six qualities when selecting an EMI analysis software program.

1. Reduces product development cost

The bottom line for any software tool is that it should be good for the bottom line.
If the software costs more to purchase and learn to use than it saves in product development and testing costs, then it doesn’t provide added value.
Return on investment can be difficult to measure for software tools, especially sophisticated analysis software. But ask yourself, is this tool going to help prevent EMI problems when we get to the test lab? If so, it warrants consideration.

2. Prevents EMI test failures

Nearly all EMI problems are preventable. Does the software predict EMI performance? Can you compare analysis results directly to EMI test limits?
Many signal integrity (SI) software tools claim to be EMI analysis tools. SI is not the same as EMC. Signal integrity tools are most helpful with self-compatibility. And for high speed digital designs, SI tools may be essential. However, using an SI tool does not assure EMC. The biggest EMC benefit of SI is in reducing radiated emissions from printed circuit boards, a small subset of the overall EMI requirements.
A good EMI analysis tool will predict EMI performance that can be directly compared to EMI test limits.

3. Improves productivity

Is the software easy to learn? Is it intuitive? Can you pick it up again quickly after several months and put it to use immediately?
Or do you have to attend training courses, dig through seemingly endless Help files, and spend your valuable time learning and relearning how to build models and perform analyses?
Fundamentally, EMI software should help you do your job better and make you more productive.

4. Augments existing capabilities

EMI analysis software should handle what matters most. The biggest, most challenging EMI compliance problems you face.
After all, if the software addresses subtle EMC issues such as printed circuit board crosstalk, but leaves your design vulnerable to RF noise coupled to power and signal cables, you are going to have problems when it comes time to pass your EMI tests.
A good EMI analysis program should supplement capabilities you already have. And should complement your strategy for pre-compliance testing.

5. Provides insight

EMI analysis software should provide awareness and understanding of the mechanisms that cause interference and compliance difficulties.
Electromagnetic interference is caused by unintended interactions between circuitry, packaging, and cabling.
Many EMI problems are the result of subtle parasitics, such as component inductance and stray capacitance, elements typically ignored during circuit design and packaging.
The analysis tool should reinforce what you already know, while shedding light on the causes and effects of various design elements. It should improve your expertise and increase your value.

6. Intuitive to use

Finally, although EMI is one of the most difficult aspects of electrical engineering, a good EMI analysis tool should be usable by anyone in your organization with an electronics background and basic knowledge of EMI requirements.
You shouldn’t need an advanced degree in electromagnetics to create models and operate the software. You should be able to quickly translate your circuit design into EMI predictions that are directly comparable to EMI test requirements.

THE TAKE AWAY

Use EMI analysis software during the design phase of your electronic products.
Select the tool that reduces product development and testing cost by preventing EMI test failures.
The right tool will improve your productivity, integrate with existing capabilities, improve your understanding of EMI, and be easy to learn and use.