EMI/EMC Design and Troubleshooting

Course 230

 Request information about bringing this course to your site.

Summary

This course covers the methodology of designing an electronic product to minimize the possibilities of having problems of electromagnetic interferences (EMI) or Electromagnetic Compatibility (EMC). Useful techniques for troubleshooting an EMI/EMC problem are presented to help in products where problems exist. The basics of designing electronic products with EMI and EMC in mind are introduced in a very understandable and entertained style. The course presents the ways in which an electronic system can generate and/or receive EMI causing failure to meet EMC regulations. A practical approach with many real world examples, techniques, simulation and hardware tools for EMI design will be explained to minimize costs, production and marketing delays considering EMI in the design phase.

First, we cover the BASICS OF EMI/EMC including coupling mechanisms, why to consider EMC, typical sources and victims, time domain vs. frequency domain, near vs. far field, non ideal components, controlling signal return currents, differential vs. common mode currents, radiation and pickup from loop and dipoles, the “hidden schematic” idea, etc.

Second part is dedicated to a key topic: GROUNDING. Signal ground versus safety ground, ground loops, grounding strategies, minimizing ground impedance, etc.

Third, the principles of FILTERING are explained: reflection vs. dissipation, source and load influence, damping resonances and ringing, insertion losses, components and layout in filters, ferrites, decoupling and bypass, mains filters, filter mounting and layout.

Fourth, the main design blocks of a system are explained: printed circuit boards (PCBs), shielding and cabling. We will discuss the DESIGN OF PCBS, component selection and placement, special components for EMI (e.g. spread spectrum clocks), typical problems, layers (how many and distribution), layout, traces, transmission line effects, ground planes, splits in planes, decoupling (how, where, distributed, resonances, etc), crosstalk and examples.

We will cover the topic of SHIELDING: influence of material, shielding effectiveness, low frequency magnetic fields, how to destroy a shield, holes and slots, gaskets, evaluation of shields, shield penetrations (how to do).

We explain how CABLES can radiate or pick-up (they are antennas), shielded cables, cable grounding, connectors, types of cables (wires, twisted pairs, coax, shielded cables, ribbon cables, etc) and their influence in the EMC profile of the product.

Finally, a review of TRANSIENTS and protection (including ESD basics) is included, firmware and EMI subjects are discussed and DIAGNOSTIC TECHNIQUES AND HINTS (including near field probes) and measurement and tests for EMC are explained.

Learning objectives

Upon completing the course you will be able to:

  • understand the basics and fundamentals of EMI/EMC issues,
  • look at the high frequency fundamentals of EMI, modelling the problems to be able to propose solutions,
  • locate and fix EMI/EMC problems in a product or installation,
  • design electronic equipment to avoid common EMI/EMC failures,
  • use lab measurements and tools to find or fix typical EMI/EMC problems,
  • perform simple prequalification EMC tests,
  • use EMI diagnostic and troubleshooting techniques to locate and fix EMI/EMC problems in existing equipment
  • reduce time and cost of EMI/EMC diagnosis and repair.

Target Audience

No prior EMI/EMC knowledge is needed but an electrical engineering background (BSEE or equivalent experience) is recommended.

This course will be of interest to:

  • design and test engineers/technicians from the electronics industry involved in EMI/EMC problems. Analog, digital, RF, mechanical and system engineers and technicians interested in design process to avoid EMC problems,
  • those interested in a working knowledge of EMI/EMC engineering principles and concerned with EMC regulations,
  • laboratory personnel involved in measurement and troubleshooting of EMC failures,
  • managers responsible for design, production, test and marketing of electronic products,
  • marketing engineers who need a general and practical knowledge of the EMI/EMC basics.

Outline

Day One

Basics of EMI/EMC
 • Why EMI affects electronic systems • why consider EMC • EMI/EMC classifications • typical sources and victims • coupling mechanisms • spectrum of a signal • time domain vs frequency domain • near vs far field • decibels • di/dt and dv/dt • non ideal components • frequency vs dimensions in EMI • controlling signal return currents • diferential vs common mode currents • “hidden antennas” radiation and pickup from loop and dipoles • the “hidden schematic” idea • how EMI/EMC tests are done, etc.
Grounding
 • Signal ground versus safety ground • Ground in high frequency/speed applications: low impedance path • Minimizing ground impedance • Common impedance • Ground strategies (single point, multipoint, hybrid) and minimizing ground impedance, etc. • Ground loops
Filtering
 • Filters for EMI/EMC • how filters work: reflection vs dissipation • insertion losses • source and load influence • parasitic and location effects • filtering with ferrites • saturation and undesired coupling effects • decoupling and bypass fundamentals • damping resonances and ringing • three terminal and feed through components • mains filters (differential mode and common mode) • filter mounting and layout

Day Two

Printed Circuit Boards (PCBs)
 • basic ideas • typical problems in PCBs • design strategy • partitioning and critical zones • choosing the PCB structure: how many layers and distribution • power planes design and distribution • layout and routing (1, 2 and multilayer) techniques • traces, microstrip and stripline, corners, vias, controlling impedance, transmission line effects and solutions • ground planes • splits or ground discontinuities in planes (slots) • decoupling and bypass (how, where, resonances, etc) • crosstalk and guards • mixed signal PCBs (A/D designs) • clocks and critical signals • Examples from real world
Shielding
 • Basic ideas • how shields work: reflection vs absortion • Influence of material • shielding effectiveness • low vs high frequency fields • electric vs magnetic fields • how to destroy a shield • holes and slots • gaskets • evaluation of shields • shield penetrations (how to do) • holes for fans and displays • Shields and paint (for good and bad results) • Transformer stray fields and real world examples

Day Three

Cables
 • Basic ideas for cable fundamentals • cables in EMI • transmission lines in EMI • cable termination • crosstalk • how cables can radiate or pick-up • The control of return current • Cable impedance • Shielded cables • cable grounding • Types of cables - wires, twisted pairs, coax, shielded cables, ribbon cables, etc • Connectors • Reducing emissions from cables • Examples from real world
Transients
 • Transients from natural and human sources • Typical transient problems - energy from inductance, ESD basics and high switching activity • Methods for transient protection - filtering, clamping and crowbar • Firmware and transients
Diagnostic and Troubleshooting
 • Diagnostic and troubleshooting techniques and hints • Locating EMI sources with near field probes • Typical fast and low cost solutions • Measurement and tests for EMC • Examples from real world