Free Trials

Download a free trial to find out which Altium software best suits your needs

How to Buy

Contact your local sales office to get started on improving your design environment


Download the latest in PCB design and EDA software

  • Altium Designer

    Complete Environment for Schematic + Layout

  • CircuitStudio

    Entry Level, Professional PCB Design Tool

  • CircuitMaker

    Community Based PCB Design Tool


    Agile PCB Design For Teams

  • Altium 365

    Connecting PCB Design to the Manufacturing Floor

  • Altium Concord Pro

    Complete Solution for Library Management

  • Octopart

    Extensive, Easy-to-Use Component Database

  • PDN Analyzer

    Natural and Effortless Power Distribution Network Analysis

  • See All Extensions

    World-Renowned Technology for Embedded Systems Development

  • Live Courses

    Learn best practices with instructional training available worldwide

  • On-Demand Courses

    Gain comprehensive knowledge without leaving your home or office

  • Altium 365 Viewer

    View & Share electronic designs in your browser

  • Altium Designer 20

    The most powerful, modern and easy-to-use PCB design tool for professional use


    Annual PCB Design Summit

    • Forum

      Where Altium users and enthusiasts can interact with each other

    • Blog

      Our blog about things that interest us and hopefully you too

    • Ideas

      Submit ideas and vote for new features you want in Altium tools

    • Bug Crunch

      Help make the software better by submitting bugs and voting on what's important

    • Wall

      A stream of events on AltiumLive you follow by participating in or subscribing to

    • Beta Program

      Information about participating in our Beta program and getting early access to Altium tools

    All Resources

    Explore the latest content from blog posts to social media and technical white papers gathered together for your convenience


    Take a look at what download options are available to best suit your needs

    How to Buy

    Contact your local sales office to get started improving your design environment

    • Documentation

      The documentation area is where you can find extensive, versioned information about our software online, for free.

    • Training & Events

      View the schedule and register for training events all around the world and online

    • Design Content

      Browse our vast library of free design content including components, templates and reference designs

    • Webinars

      Attend a live webinar online or get instant access to our on demand series of webinars

    • Support

      Get your questions answered with our variety of direct support and self-service options

    • Technical Papers

      Stay up to date with the latest technology and industry trends with our complete collection of technical white papers.

    • Video Library

      Quick and to-the-point video tutorials to get you started with Altium Designer

    Introduction to High Speed PCB Designing: How to Eliminate Crosstalk

    Altium Designer
    |  November 8, 2017
    Introduction to High Speed PCB Designing: How to Eliminate Crosstalk

    Recently at a wedding reception I was trying to talk to a gentleman who was sitting at the same table as me. Unfortunately there was a woman sitting between us carrying on a conversation with someone else sitting on my other side. With all the commotion of the reception in the background, conversation was difficult to begin with. Having another discussion taking place between us though made our conversation impossible. What we had was crosstalk!

    Crosstalk during a conversation can be very annoying, but crosstalk on your PCB layout can be disastrous. If not corrected, crosstalk can cause your finished circuit board to either not work at all, or it may be plagued by intermittent problems. Let’s take a look at what crosstalk is and what you can do to prevent it.

    What is crosstalk in high speed PCB designing?

    Crosstalk is the unintentional electromagnetic coupling between traces on a PCB. This coupling can cause the signal pulses of one trace to overpower the signal of the other trace even though they are not physically touching each other. This can happen when the spacing between parallel traces is tight. Even though the traces may be maintaining the minimum spacing for manufacturing purposes, it may not be enough for electromagnetic purposes.

    Consider two traces running parallel to each other. If the signal in one trace has more amplitude than the other, it could aggressively influence the other trace. The signal in the “victim” trace will then begin to mimic the characteristics of the aggressor trace instead of conducting its own signal. When this happens, you have crosstalk.

    Crosstalk is usually thought of as happening between two parallel traces running next to each other on the same layer. There is an even greater possibility, though, for crosstalk to occur between two parallel traces running next to each other on adjacent layers. This is called broadside coupling, and it is more likely to happen because the two adjacent signal layers are separated by a very small amount of core thickness. This thickness can be 4 mils (0.1 millimeters) which is sometimes less than spacing between two traces on the same layer.

    Blue highlighted traces on a black and white circuit board
    Trace spacing to eliminate crosstalk is typically larger than regular trace spacing requirements

    Removing the potential for crosstalk from your design

    Fortunately you are not at the mercy of crosstalk. By designing your board to minimize the potential of crosstalk situations, you can avoid these problems. Here are some design techniques that will help you to eliminate the possibility of crosstalk on your board:

    1. Keep as large of a distance as possible between differential pairs and other signal routing. The rule of thumb is gap = 3 times the trace width.

    2. Keep as large of a difference as possible between clock routing and other signal routing. The same gap = 3 times the trace width rule of thumb works here as well.

    3. Keep as large of a distance as possible between different sets of differential pairs. The rule of thumb here is slightly larger, gap = 5 times the trace width.

    4. Asynchronous signals (like RESET, INTERRUPT, etc.) should be routed away from busses and high speed signals. They can be routed next to on and off or power-up signals though, because those signals are rarely used during the normal operation of the board.

    5. Make sure that two signal layers adjacent to each other in the board stackup will alternate horizontal and vertical routing directions. This will reduce the chance of broadside coupling by not allowing the traces to run parallel on top of each other.

    6. A better way to reduce potential crosstalk between two adjacent signal layers is to separate the layers with a ground plane layer between them in a microstrip configuration. Not only will the ground plane increase the distance between the two signal layers, it will also provide the required return path for the signal layers.

    Picture of computer screen with hand holding a wrench coming out of it
    Your PCB design tools and third-party applications can help you to eliminate crosstalk

    How your design software helps you to eliminate crosstalk in high speed PCB designing

    PCB design tools have a lot of functionality built into them to help you to avoid crosstalk in your designs. Board layer rules will help you to avoid broadside coupling by specifying routing directions, and creating microstrip stackups. With net class rules, you will be able to assign greater trace spacing to groups of nets that are more susceptible to crosstalk. Diff pair routers will route your differential pairs together as an actual pair instead of routing them individually. This will maintain the required spacing of the differential pair traces to each other and to other nets in order to avoid crosstalk.

    In addition to the built in functionality of your PCB design software, there are also other tools that can help you to eliminate crosstalk in high speed PCB designing as well. There are different crosstalk calculators available to help you determine the proper trace width and spacing for your routing. There are also signal integrity simulators to analyze your design for potential crosstalk problems.

    Crosstalk can be a big problem on a printed circuit board if allowed to happen. Now that you know what to look for though, you will be prepared to prevent crosstalk from happening. The design tips that we have discussed here along with the functionality in your PCB design software will help you to create a crosstalk free design.

    PCB design software, like Altium Designer, has the advanced functionality that we’ve discussed here already built into it. Would you like to find out more about how Altium Designer can help you to work through crosstalk and other signal integrity issues in your PCB design? Talk to an expert at Altium Designer.

    About Author

    About Author

    PCB Design Tools for Electronics Design and DFM. Information for EDA Leaders.

    most recent articles

    Back to Home