EMC Consutancy & Design solutions

In around 90% of CE (Conducted Emission)  issues on the mains input, the solution is simple: just add a common-mode (CM) filter .Most of the time, I use Würth Elektronik  filters — they’re reliable and predictable. However, every once in a while, something strange happens.Instead of reducing  the conducted emissions, the filter actually makes them worse  — sometimes by several dB between 1 MHz and 30 MHz .Let’s see why this happens and how to fix it. The Typical Setup In a st

If you are an electronic designer engineer you may want to read this article.... Surge and transient immunity testing often reveals weaknesses that are hard to predict during design. In one of my recent EMC test sessions, I encountered a case that perfectly illustrates why component-level surge ratings  can be misleading — and why system-level surge design  is what really matters. The Setup The test involved surge testing on an input port connected through cables longer than

Introduction Varistors (typically MOVs) are widely used on mains lines for surge / transient protection. Under normal conditions they are passive, but when high‐voltage transients (switching surges, lightning induced, line over­voltage) occur, the varistor conducts, clamps the voltage and absorbs energy. Over time the repeated stress (especially large impulses) causes the varistor’s characteristics (e.g., breakdown/clamp voltage) to degrade. Eventually the device may fail (ei

Today I want to talk about how apparently short  PCB tracks can still create big EMC problems —especially when they carry a clock in the 20–30 MHz  range. A very common setup You’ve got a clock source (XO or MCU clock out) driving something like a USB/Ethernet transceiver or an SPI flash. The driver is low-impedance (≈ 20 Ω), the track length is, say, 25 cm , and the receiver load is around 10–20 pF . Let’s pick a concrete example: 25 MHz  clock. If you only look at the funda

What I’m trying to show you today is counterintuitive. If you’re failing radiated emissions around 200–230 MHz  by just 3–4 dB , there’s...

Scope:  Why some products show broadband  radiated emissions from 30 MHz–1 GHz , why issues often persist up to 400 MHz–1 GHz  even on...

Scope:  How to read narrowband  features on the RE plot (100–1000 MHz is where they often pop up) and trace them back to clocks,...

Goal:  Use the radiated emissions (RE) plot to quickly identify the likely noise source and prove it with simple, low‑risk tests. 1)...

High-speed differential pairs, such as those found on HDMI lanes are more than just tightly coupled traces. At multi-gigabit speeds, the...

Thermal-relief “spokes” help solderability, but they add inductance  and cut slots  in your reference plane—exactly where high-frequency...

Here is an interesting conundrum I faced some years ago whilst I was working on a product subjected to heavy fields of over 50 V/m during...

Quick Recap of Part 1 In Part 1, we explored how a simple change in antenna orientation  can help you tell whether a radiated emission is...

Any electronic product must be compliant with the appropriate EMC (Electromagnetic Compatibility) therefore the designer engineer should...

In this post, I’ll share a powerful debugging technique you can use to identify the source of emissions in the 30 MHz to 300 MHz range....

The RS422 and RS485 standards are well known in the industry for their reliability and noise immunity. However, they do hide the seeds...

In one of my previous blogs, I discussed the importance of adding common mode filtering to power cables. Nevertheless, even the best...

The following tips may be helpful if you're designing a solution that uses a 10/100 LAN Ethernet port. Some very common Ethernet PHY...

Let's learn how to fix emissions due to clock lines. Over the course of my career, I have helped many companies resolve EMC issues. One...

In terms of EMI, it is very difficult to have a product that is both efficient and low noise. Today I'd like to discuss some typical...

Last year I worked with Cryptalab on the design of a quantum random number generator card. SSL/TSL experts know how important this is in...