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

    Conducted Emissions Test Equipment and Reduction Guidelines

    August 24, 2017

    Lab test receiver

    One of my classes in college was so difficult that the professor would give us the test questions a week in advance. Even knowing exactly what to study for the exam, lots of students still failed. Conducted emissions analysis for electromagnetic compatibility (EMC) is similar. Devices need to be checked to see if they’re putting too much noise back into the grid through their power supply. Otherwise, the FCC will think you’re disrupting utility power. It’s not difficult to pre-test devices for EMI conducted back into the power source through the power supply. However, lots of products still fail when it comes time for the final check. Failure at the last stage costs a lot in both time and money. All that can be avoided by preparing yourself with the right equipment and doing some pre-compliance testing. It’s also a good idea to look at your PCB design and power supply to try and root out any conduction problems at the source.

    Benefits of Pre-Compliance Testing

    We also had several classes back then with examinations that were open book. Lots of students wouldn’t study beforehand because they thought if they had their books the test would be easy. They were wrong, and lots of them failed. Lots of people assume that the conducted emissions part of EMC is simple compared to radiated emissions, but they cause just as many failures.

    If you have a conducted emission test failure, you’ll have to do it again, which can cost thousands of dollars. Failing a college exam is bad, but a blunder in these tests is like failing a whole class. Pre-compliance equipment is expensive, but not as costly as repeat certification testing. Failing an EMC assessment can also delay getting your product to market. If you have major fixes that need to be done it could significantly delay your project. Better to catch problems at the beginning when they’re relatively easy to fix.

    Multiple choice test
    And you thought college tests were hard.

    Pre-Compliance Equipment

    The equipment you’ll need for conducted emissions is fairly similar to that required for radiated emissions. A kit like this will cost you several thousand dollars.

    • Spectrum (Required) - A spectrum is the backbone of pre-compliance testing. This will allow you to analyze any electromagnetic interference coming out of your board. This will likely be the most expensive piece, costing upwards of $1,000.

    • Software (Required) - An open book test isn’t helpful if you don’t know how to read, just like a spectrum without software. Some spectrum analyzers come with software included. If yours doesn’t, make sure you choose one that is compatible with free programs.

    • Line Impedance Stabilization Network (LISN) - This is one thing you need for conducted emissions that you don’t for radiated emissions. A LISN isolates your device from any noise in the power source and matches impedance so that your spectrum analyzer can operate accurately. If you want your tests to be really accurate, you might need two of these.

    • Pre-Amplifier (Optional) - A pre-amp will boost any frequency signals coming out of your device, making them easier to read. It’s not necessarily required, but might be a good idea.

    Picture of a PCB
    Careful routing and grounding will help you avoid conducted EMI.

    Possible Problems

    Now that you have all your equipment it’s time to test your product. If everything turns out to be fine, you might resent me for getting you to do pre-compliance, but I’m okay with that. Alternatively, if there’s a problem, it’s likely that the source of it is in your power supply or PCB. Things like crosstalk and ground loops can both amplify noise in your , which can then be conducted out through your power supply.

    While your chosen power supply may supposedly already be compliant, the reality can be different. A specific supply may have come from a bad batch. Power supplies are also sometimes only tested with DC current frequency, and AC noise coming from your can force them out of compliance. Regardless of the reason, if your supply is non-compliant, your device probably will be as well. Pre-compliance testing can help you determine if you chose the right supply, or if you need to make a change before finalizing your designs.

    Crosstalk happens when signals on your board go where they’re not supposed to. There are many causes of crosstalk including: mixed AC/DC signals, poor differential pair routing, and poor high speed routing. Generally you’ll want to keep interfering signals far away from other circuits. You should also keep traces short to keep them from radiating EMI like antennas.

    Ground and power planes can also be sources of trouble for your PCB. Generally ground and power planes help attenuate EMI, but if you create ground or power loops in them you’ll have a problem on your hands. To avoid doing that you should carefully design your ground planes.

    You should always try to pass EMC certification tests the first time. Repeat assessments will cost you time and money and are easily avoided. Performing tests yourself and catching problems early is the way to go. Even better, you can further prevent issues by designing a PCB for EMI reduction. Try to reduce crosstalk and eliminate ground loops so that your circuit passes the initial test.

    The theory of EMC PCB design is all well and good, but the practice can be another story. Great PCB design software like CircuitStudio® can help you put into practice all these principles. It has lots of advanced tools that will make your job a breeze.

    Have more questions about conducted emission test failure? Call an expert at Altium.

    Check out Altium Designer® in action...

    Powerful PCB Design

    most recent articles

    Back to Home