By law, electronic devices sold in the United States, European Union and other major markets are required to demonstrate that they comply with regulations for electromagnetic compatibility, or EMC.
In the United States, electromagnetic compatibility is regulated by the Federal Communications Commission (FCC). In Europe, regulations such as the Electromagnetic Compatibility Directive and Radio Equipment Directive (RED) provide clear standards for electronic devices.
A key part of achieving compliance with EMC regulations is ensuring that your device operates within the legal limits for electromagnetic radiation.
Another key step is verifying that your device has sufficient immunity to emissions produced by other devices.
This can be done using a variety of techniques, including the use of grounding and shielding in your device, effective PCB layout strategies, and through other small changes to your device’s design and components.
Below, we’ve explained what electromagnetic interference is, as well as why it’s so important to control electromagnetic interference in order to achieve regulatory compliance for your device.
To learn more about EMC testing and compliance, or to request a quote for testing your device and achieving FCC and/or CE compliance, contact us online or call our team of engineers and compliance specialists at 866-540-5287.
What is Electromagnetic Interference?
Electromagnetic interference is an issue that occurs when an electronic device is made unable to operate normally due to the effects of an electromagnetic field. It can occur in areas with lots of electronic devices and can cause everything from mild issues to severe malfunctions.
When a device is affected by electromagnetic interference, it may stop functioning normally, or provide inaccurate readings. In certain cases, the effects of electromagnetic interference could result in health and/or safety issues.
EMI is a common issue in many industries. For example, industrial equipment, medical devices and even consumer electronics can all be affected by EMI.
Common Causes of Electromagnetic Interference
A variety of different factors can cause or contribute to electromagnetic interference, including natural events and man-made issues. We’ve discussed these causes below and explained the impact they can have on your device’s performance.
Natural Causes of Electromagnetic Interference
Many natural events can cause electromagnetic interference. For example, it’s common for EMI to develop in response to lightning, solar flares, and other natural weather events that generate electromagnetic energy.
Other natural phenomena, such as electrostatic discharge that occurs when you walk across a carpet and touch a metal object, can cause interference. Certain types of atmospheric noise in the atmosphere can also cause interference that affects electronic devices.
Man-Made Causes of Electromagnetic Interference
The most common man-made causes of interference are other electronic devices, certain types of power supplies, and communication systems.
Almost all electronic devices emit electromagnetic energy that may cause interference. Devices such as mobile phones, communications equipment, industrial machinery, and other equipment can potentially cause interference.
Interference is particularly common with devices that intentionally emit radio frequency energy, such as phones and Wi-Fi equipment.
Some power systems and power lines can cause interference. For example, high-voltage lines can generate electromagnetic fields that may interfere with electronic equipment in the nearby area. Some switching power supplies can also generate noise that causes interference.
Finally, industrial machinery, medical devices, ignition systems in vehicles, and other types of equipment can also generate electromagnetic energy that may cause interference.
Our guide to the causes of electromagnetic interference offers more information about natural and manmade issues that can cause EMI.
EMI and Regulatory Compliance for Electronic Devices
All major markets have regulations for electromagnetic interference. These regulations set limits for a device’s emissions (the amount of energy that can be emitted from the device) and for the device’s ability to tolerate emissions from other devices (referred to as “immunity”).
In order to achieve regulatory compliance, your device will need to operate within the emissions limits for its target market and demonstrate that it has sufficient immunity to continue functioning when it’s exposed to emissions from other electronic equipment.
Your device’s emissions and immunity are assessed through EMC testing, which involves using specialized equipment to measure your device’s emissions and monitor its performance when it is exposed to targeted emissions itself.
How to Reduce Electromagnetic Interference
Reducing electromagnetic interference from your device is a key step in achieving compliance with regulations such as FCC Part 15, Canada’s ISED rules, and the EU’s EMC Directive and Radio Equipment Directive (RED).
Numerous techniques are used to reduce emissions from electronic devices, including the use of shielding, grounding, cable management, and changes to your device’s circuit board layout.
In some cases, changes to your device’s software can also help to reduce emissions and bring your device into compliance with regulations.
Below, we’ve listed the most common methods of reducing electromagnetic interference:
- Grounding. One of the most effective ways to reduce EMI is to ensure your device is properly grounded. Grounding dissipates electromagnetic interference through a safe path to the ground, which can help to reduce your device’s emissions.
- Shielding. Using conductive or magnetic materials to encase electronic components and circuits in your device can also help to reduce EMI. Proper shielding stops fields from escaping your device by either absorbing or reflecting them.
- Cable and connector management. Using shielded cabling for your device’s power and signal lines can help to reduce emissions. Other steps, such as minimizing your device’s cable loop area, can also help to reduce emissions and interference.
- Component placement and PCB layout. Certain techniques, such as locating your device’s high-speed components away from the edges of the PCB and reducing loop area, can reduce emissions and interference caused by your device.
- Decoupling and bypass capacitors. Capacitors can help to limit interference caused by your device. Common techniques include placing decoupling capacitors close to the power supply pines of the circuit and using bypass capacitors on power supply lines.
- Spread spectrum clocking. This technique involves varying the clock frequency over time. Spread spectrum clocking spreads your device’s energy over a wider frequency band, which can help to reduce peak emissions.
- Differential signaling. Differential signaling involves sending the same electrical data signal as a positive and negative inverted signal over two wires. Like other approaches, this can help to reduce emissions and limit EMI caused by your device.
- Software solutions. In certain cases, making changes to your device’s software may reduce emissions. This may include adjusting the operating frequencies of processors and other components, or using software to control power consumption.
Need help reducing your device’s emissions for regulatory compliance? Contact us to talk with our engineers and compliance specialists to learn more about the most effective techniques for reducing EMI from your device.
Contact Us for Help With EMI & EMC Testing
As an ANSI-accredited electronics testing lab, we specialize in EMI/EMC testing for electronic devices aimed at markets such as the United States, Canada, the European Union and others.
Our experienced team can test your device and help you achieve compliance with FCC and/or international regulations, allowing you to add compliance marks to your device and gain global market access.
To find out more about EMI/EMC testing and compliance, or to request a quote for your device, contact us online or call us at 866-540-5287.
