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Last updated on 2024年9月19日

You're tackling PCB layout design. How can you avoid EMI problems?

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When designing printed circuit boards (PCBs), electronic engineers must navigate the challenge of electromagnetic interference (EMI), which can disrupt the performance of electronic devices. EMI problems can arise from a variety of sources and can affect both the device in question and nearby electronics. To ensure your PCB design is robust against such interference, it's crucial to understand and implement strategies that can mitigate EMI from the outset.

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Waseem Alkhayer

Hardware Development Manager

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Mark H.

Engineering Content Creator | High Performing Videos, Articles and Real World Hardware

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Daniel Ismail

Electronic Design Engineer @ PWB Design Service | Circuit Design, Embedded Systems

1 Grounding Techniques

A fundamental strategy to avoid EMI problems is to use proper grounding techniques. Your PCB should have a solid ground plane that serves as a reference point for all components. This helps to stabilize the voltage levels and provides a path for EMI to return to the ground instead of coupling into signal paths. When laying out your PCB, keep the ground plane unbroken and as extensive as possible, and connect it to a common point to avoid ground loops, which can act as antennas for EMI.

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Mark H.

Engineering Content Creator | High Performing Videos, Articles and Real World Hardware
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Good grounding's essential, but don't forget about power! A solid power distribution network is just as crucial for keeping EMI in check. Try using power planes when you can - they're brilliant for lowering impedance. If you're tight on layers, a grid of power traces can work a treat too. Mind Your Decoupling Remember to sprinkle decoupling caps liberally around your board. They're like little EMI sponges, soaking up high-frequency noise before it can cause trouble. Pop them close to power pins, and use a mix of values to catch different frequencies. Oh, and keep those traces to the caps nice and short - long ones defeat the purpose!

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Karthika Hariharan

Project Management | Power Electronics Design | Full bridge inverter based Product Life Cycle | Project Life Cycle | Agile I Scrum | PCBA design: Altium, OrCAD, Zuken | IEC standards | Component Engineering |
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After doing all the regular checks for grounding, following IC design guidelines, For high speed designs, it is important to closely work with the PCB manufacturer to get the required impedance of the trace. And it should be done for proto types and with regular production pcb manufacturer.

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Tanmay Sharma

Senior Associate (R&D) - Providing solutions to the world's most complex engineering problems ?
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Utilize Continuous Ground Planes: Implement solid ground planes to provide low-inductance paths and effective shielding against EMI. Employ Star Grounding: Connect all grounds to a single point to reduce ground loops and interference between circuits.

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MOHAMMAD ADIL

Experienced Hardware Designer driving cutting-edge technological advancements
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Grounding is important. when done properly, it will reduce EMI significantly. - Ensure there is no component, traces at the edge of the PCB. All the Edges should have ground only, stiching via will be cherry on cake. - High speed traces and differential traces shall be have ground adjacent to it. - Avoid ground under electro mechanical switch like Relay. It introduces noise in the ground. - No need of Split ground, as i acts as an antenna. - Grounding around RF antenna shall be proper as per its recommendation.

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Ahmer Kayani

Senior Hardware Design Engineer & Team Lead Hardware Development | FPGA Developer
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Proper grounding is essential for mixed-signal and high-speed PCBs, especially when power management circuits (e.g., switching regulators), analog circuits (e.g., audio, video), and high-speed signals (e.g., digital image signals, sensor data) coexist on the same board. Using a dedicated PCB layer with unbroken ground plane helps minimize crosstalk from switching currents and reduces both conductive and radiative EMI. Additionally, grouping components by signal type into blocks on the PCB, rather than spacing them far apart, reduces current loops and improves overall performance.

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2 Trace Routing

Careful trace routing on your PCB can significantly reduce the risk of EMI. Keep signal traces short and direct to minimize the area they can couple with adjacent traces. When routing high-speed or high-frequency signals, maintain a safe distance from other traces to prevent crosstalk. Additionally, running parallel traces close together for extended distances should be avoided as this can create a loop antenna that is susceptible to EMI.

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Daniel Ismail

Electronic Design Engineer @ PWB Design Service | Circuit Design, Embedded Systems
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For high-speed signals, it's best to route them as striplines to ensure optimal signal integrity and reduce noise. To minimize crosstalk, ensure there's sufficient clearance between signal traces. Additionally, don’t forget to follow the 45-degree rule or make turns even smoother to avoid signal reflection and maintain signal quality, especially in high-frequency designs. Proper routing and spacing are key to preventing unwanted interference and maintaining overall performance.

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3 Component Placement

Strategic component placement is vital in minimizing EMI. Place sensitive components away from sources of noise, such as high-speed processors or switching power supplies. Group related components together to minimize the length of critical signal paths and use shielding methods, like metal cans or guard traces, around highly sensitive parts. By doing this, you can create localized circuits that are less prone to external interference.

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Daniel Ismail

Electronic Design Engineer @ PWB Design Service | Circuit Design, Embedded Systems
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Component placement is crucial as it directly influences trace routing and the return current path. Be sure to adhere to design standards when positioning components. It's also best to arrange components in a straight and serialized manner rather than creating nodes, which helps maintain signal integrity and simplifies routing.

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4 Decoupling Capacitors

Decoupling capacitors are essential in any PCB layout to filter out noise. Place these capacitors close to the power pins of integrated circuits (ICs) to provide a clean power supply and reduce voltage spikes that can generate EMI. Use a mix of capacitor values to cover a broad range of frequencies; typically, a combination of larger electrolytic capacitors for low-frequency decoupling and smaller ceramic capacitors for high-frequency noise is effective.

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Daniel Ismail

Electronic Design Engineer @ PWB Design Service | Circuit Design, Embedded Systems
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Decoupling capacitors can amplify noise if they're not placed correctly or if the wrong capacitance values are used. Placing them too far from the IC increases parasitic inductance, causing resonance and amplifying noise at specific frequencies. Similarly, using inappropriate capacitor values can lead to resonance with system noise. To avoid this, place capacitors close to power pins and select a range of capacitance values for effective noise filtering.

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5 Shielding and Filtering

Incorporating shielding and filtering into your design can further protect against EMI. Metal shields can be placed over noise-sensitive areas or noise-generating components to prevent EMI from entering or exiting those regions. Filters, such as ferrite beads or low-pass filters, can be added to interface lines to block high-frequency noise while allowing the desired signals to pass through. This is particularly important for connectors that act as entry and exit points for EMI.

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6 PCB Stack-Up

Finally, consider the PCB stack-up—the arrangement of copper and insulating layers in a multilayer PCB. A well-designed stack-up can provide inherent EMI protection. For instance, sandwiching signal layers between ground planes can shield them from external noise. Also, ensure that high-speed signal layers are internal and close to a ground plane, which helps to contain the electromagnetic fields and reduce emissions.

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Waseem Alkhayer

Hardware Development Manager
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At high frequencies, the current through a signal trace on a PCB wants to return directly underneath the trace. The best way to achieve this is to ensure there is a reference plane (typically GND) directly below the trace, and there are no gaps or splits in the plane. At DC or low frequencies <100kHz, the return current takes the shortest path straight through the copper plane back to the source. However at high frequencies the current travels back through the plane on a path that is directly underneath the trace. Understanding the energy flow in a PCB is a key to designing the PCB stack-up and routing the signals.

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Daniel Ismail

Electronic Design Engineer @ PWB Design Service | Circuit Design, Embedded Systems
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The PCB stack-up is critical for minimizing noise and ensuring effective EMC performance. A well-designed stack-up should account for cross-coupling, ensuring proper signal integrity. Additionally, maintaining a clear and efficient return path for both signals and power lines is essential for reliable performance in high-speed designs.

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Nishidh P

AM PCB Design
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- Better to providing shielding for traces above 10MHz, - Minimum via usage for the clock and high speed traces, Avoid stubs on high speed nets, - floor planning for placement of power supply region and high speed interfaces. - impedance continuity throughout the signal path.

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You're tackling PCB layout design. How can you avoid EMI problems?

1

2

3

4

5

6

1 Grounding Techniques

2 Trace Routing

3 Component Placement

4 Decoupling Capacitors

5 Shielding and Filtering

6 PCB Stack-Up

Electronic Engineering

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You're tackling PCB layout design. How can you avoid EMI problems?

1

2

3

4

5

6

1 Grounding Techniques

2 Trace Routing

3 Component Placement

4 Decoupling Capacitors

5 Shielding and Filtering

6 PCB Stack-Up

Electronic Engineering

给文章评分

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