How can you reduce electromagnetic emissions and susceptibility?

1 Identify potential sources and paths of electromagnetic interference

The first step to reduce electromagnetic emissions and susceptibility is to identify the potential sources and paths of electromagnetic interference (EMI) in your design. EMI can be classified into two types: conducted and radiated. Conducted EMI refers to the unwanted signals that travel along wires, cables, or traces, while radiated EMI refers to the unwanted signals that propagate through the air or space. Some common sources of EMI are switching power supplies, digital circuits, motors, relays, and antennas. Some common paths of EMI are power lines, signal lines, ground loops, and coupling mechanisms. By identifying the sources and paths of EMI, you can apply appropriate measures to reduce or eliminate them.

2 Design your circuits and layouts for low emissions and high immunity

To reduce electromagnetic emissions and susceptibility, it is necessary to design circuits and layouts for low emissions and high immunity. This involves minimizing the generation, propagation, and reception of EMI in devices and systems. Some tips for doing this include using low-impedance power and ground planes with capacitors for decoupling, opting for differential signaling, twisted-pair cables, and shielded connectors for high-speed or sensitive signals, avoiding long traces, loops, stubs, and discontinuities that can act as antennas or resonators, separating analog and digital circuits with proper filtering and isolation techniques, choosing components with low EMI characteristics such as low-noise amplifiers, low-dropout regulators, and ferrite beads, as well as using proper grounding, bonding, and shielding techniques to prevent common-mode and differential-mode currents.

3 Test and measure your devices and systems for EMC compliance

The final step to reduce electromagnetic emissions and susceptibility is to test and measure your devices and systems for EMC compliance, verifying that they meet the relevant EMC standards and specifications for your intended application and market. Common EMC tests include conducted emissions tests, which measure the EMI signals that are injected into the power supply or other conductors by your device or system, as well as radiated emissions tests, which measure the EMI signals that are radiated from your device or system into the surrounding environment. Additionally, conducted immunity tests measure the ability of your device or system to withstand EMI signals that are applied to the power supply or other conductors, while radiated immunity tests measure the ability of your device or system to withstand EMI signals that are applied to the antenna or other receptors. You can perform these tests in a certified EMC laboratory or a shielded chamber with specialized equipment such as spectrum analyzers, signal generators, power amplifiers, and antennas. Additionally, pre-compliance testing tools and methods can be used to check your design for potential EMC issues before going to the final testing stage.

4 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?