Engineering Blog

The physics behind
great hardware.

EMC strategy, PCB design, and the thinking that separates hardware teams who reduce EMC risk systematically from those who don't. By Dario Fresu, Principal EMC Architect.

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Your team keeps failing EMC tests. The reason is conceptual.

It's not a layout problem. It's not a component problem. It's a mental model problem — and until your team replaces "grounding and shielding" with "return paths and field containment," you'll keep losing weeks to the chamber.

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Radiated Emissions Testing and the Role of EMC Current Clamps

How current clamps capture differential and common mode currents, translate them into estimated field strength, and help engineers identify emission sources before they reach the chamber.

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Redefining Current and Charge: A Field-Based Perspective on Electromagnetism

Electrons drift at 73 µm/s. Signals propagate at 150 million m/s. Something in the classical model is wrong. A field-first reframing resolves the contradiction and changes how you design.

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Why Smart Engineers Fail EMC Tests (It's Not What You Think)

The failure isn't technical knowledge — it's the mismatch between how engineers model electromagnetic behaviour and how physics actually works.

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Optimizing PCB Stackup Design: Power and Return Path Considerations

The layer sequence you choose in the first 20 minutes of a new board determines most of your EMC outcome. Here's how to get it right.

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EMC Filter Topologies: EMI Control Strategies in Electronics Design

Five filter configurations, their insertion loss behaviour, and exactly where each belongs — as a function of the impedance environment, not folklore.

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Managing EMI: Low and High-Speed Signal Return Currents

Return current doesn't follow ground. It follows the path of least impedance — and at high frequency, that's nothing like what you drew in the schematic.

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How to Conduct an EMI Design Review for Your PCB

A structured walkthrough of a full EMI design review — from stackup to connector placement. What to look for, in what order, and why.

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Understanding Radiated Emissions: What You Need to Know for EMI Compliance

How radiated emissions arise from differential and common mode currents — and how layout, stackup, loop area, filtering, and shielding decide whether your design passes FCC and CE testing.

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Understanding ESD: How to Protect Your Electronics from Electrostatic Discharge

Why ESD current ignores the earth wire and rides parasitic capacitance instead — from the triboelectric effect and human body model to chassis bonding, TVS placement, and plastic enclosures.

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Conducted Emissions

Why products fail the 150 kHz–30 MHz conducted emissions test — and how the LISN, SMPS parasitics, and proper EMI filter design determine whether yours passes.

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Power Delivery Network (PDN) for Low EMI

How to design a power delivery network that keeps EMI under control: transient current calculations, decoupling myths, placement strategy, and how many capacitors you actually need.

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PCB Layout Review for EMC and Signal Integrity — MPPT Charge Controller

A line-by-line EMC and signal-integrity review of an MPPT solar charge controller PCB — two-layer stackup pitfalls, antenna-like pours, crosstalk, stubs, and what to do when you can't add layers.

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i.MX8 SOM — EMI Design Layout Review

A layer-by-layer EMC review of an i.MX8 system-on-module — stackup pairing, return reference planes, copper-pour antennas, plane splits, and missing return vias.

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The Concept of Electromagnetic Fields in a PCB

PCBs don't conduct electrons — they guide electromagnetic fields. Understanding what that means changes how you lay out every trace.

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Understanding 90-Degree Bends in PCB Design

Settled by impedance discontinuity analysis and the frequencies you're actually running — not by folklore or outdated rules of thumb.

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Power Planes as Return Reference Planes: Challenges and Solutions in Multilayer Stackups

The challenges of using power planes as return reference planes in multilayer stackups — and the design solutions that avoid the EMI cost.

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Mastering Electromagnetic Interference: Elevate Electronics with EMC Design

Where EMI comes from, how it couples into your circuits, and the design discipline that keeps it under control from the first schematic.

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Mastering PCB Design with IPC-2221: The Industry's Foundational Standard

What IPC-2221 covers, why it's the foundational standard for PCB design, and how to apply it to spacing, materials, and reliability decisions.

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The Essentials of Electromagnetic Compatibility Training

Why EMC training matters for device reliability and compliance — and what a useful curriculum actually covers, from theory to hands-on testing.

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Why ‘Ground’ Falls Short: A Call for a Clearer Term in Circuit Design

Where the term "ground" came from, why it misleads, and how return current actually behaves — from resistance-driven spreading at low frequency to tight trace-hugging loops at high frequency.

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Understanding EN 61000-4-6: A Key Standard for Conducted RF Immunity in EMC Design

The conducted RF immunity standard from 150 kHz to 80 MHz: CDN injection setups, 1/3/10 V test levels, performance criteria A/B/C, and how to design for it up front.

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How Return Reference Planes Impact EMI Control in PCB Design

Why routing signal and power traces adjacent to a continuous return reference plane is the overlooked fundamental of EMI control — from the schematic "ground" misconception to loop area and compliance.

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Why EMI Keeps Ruining Your PCB Designs (And What to Do Before It’s Too Late)

Most PCB EMI problems arise internally — from stackup choices, impedance discontinuities, broken signal references, and layout-driven EM fields. How to tackle each at the source.

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The Pitfalls of Overreliance on Post-Design Fixes in EMC Compliance

Filters, shields, and retrofitted grounding added after layout treat symptoms, not causes. Integrating EMC from the first design phase is the cheaper path to compliance.

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Signal Integrity: The Key to EMC Compliance for Electronic Engineers

Reference plane integrity, crosstalk, and trace impedance decide whether a board passes radiated emissions — with concrete steps to stay inside CISPR 32 limits.

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Optimizing PCB Layout for EMI Control: Managing Fast-Changing Currents

Physics-based layout for high di/dt currents: loop minimization, ground-plane field cancellation, and prioritizing the switch and diode loops in buck converters.

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Mastering Input Filter Design: Achieving EMC Compliance for Power Converters

How input filters suppress conducted EMI in switching converters, their effect on closed-loop stability, and LISN-based testing against EN 55022 limits.

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Mastering PCB Design: Tips for Beginners

Practical tips for getting started: essential software like KiCad and Altium, layout and routing best practices, manufacturing constraints, and testing your first board.

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Your First Steps in PCB Design: A Beginner’s Guide

A structured starting path: key terms like schematics and Gerber files, software options from KiCad to Altium, and a walkthrough of designing, ordering, and testing your first board.

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A Field-Centric View of Energy Transfer in Classical Electromagnetism

Where does electrical energy actually flow? Not through the wire. The Poynting vector and Gauss's law inverted — with practical consequences for PCB design.

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Common-Mode Filters: Why Most Engineers Install Them In The Wrong Place

Placement is a physics constraint, not a preference. A filter in the wrong location can make emissions worse.

The Pre-Compliance Mindset: Run Your Own EMC Scan Before the Chamber

Build the diagnostic reflex that connects every bump in the scan to a physical structure in your design.

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Dario Fresu

Dario Fresu is a fourth-generation electrical professional, IPC Certified Interconnect Designer, and former ETH Zurich lead hardware engineer. He has trained thousands of engineers worldwide and built one of the largest independent EMC education platforms in the industry.