EMC design of equipment (module 1)

Goals

The objectives of the training EMC design of equipment (module 1) :

At the end of this training course, trainees will have gained in-depth knowledge of concrete solutions for EMC protection and signal integrity for inputs/outputs with associated cables and certain internal functions at the level of electronic cards and systems. The course will enrich their knowledge of the EMC behavior of components and recommendations for associated routing.

The aim of this training course is to:

• Learn to identify and solve potential problems in analog, digital, and switching circuits


• Be able to analyze and master coupling mechanisms


• Be able to design and implement conduction and radiation remedies


• Be able to understand requirements and implement shielding solutions

Program

1/ Introduction
• EMC analysis method
• Common mode and differential mode
• Use of decibels
• Time-frequency conversion


2/ EMC regulations and tests
• European directive
• Harmonised standards
• DO160 / MIL STD
• Conducted and radiated emissions
• Conducted and radiated immunity
• EMC qualification plan


3/ EMC of active components
• Signal-to-noise ratio
• Bandwidth and sweep speed
• Impedance and output current
• Envelope detection
• Static and dynamic noise margin
• Waveform and equivalent frequency
• Transition power consumption


4/ Switching circuits
• MD and MC of a switching power supply
• Common mode calculation and filtering
• Differential mode calculation and filtering
• Common mode input to output


5/ Common impedance coupling
• Principle of common impedance coupling
• Impedance of a copper plane
• Impedance of tracks and wires
• Star power supply
• Analogue/digital comparison
• Ground and power planes
• Optimal solution for CIP layers


6/ Board-to-chassis coupling
• Capacitive board-to-chassis coupling
• Capacitance between board and ground
• Capacitance of a track
• Electrostatic screen and guard ring
• Example of layout
• Mechanical ground / electrical ground
• Connection of 0 V to the chassis


7/ Coupling via crosstalk
• Linear capacitance between tracks and between wires
• Wire-to-wire inductive coupling
• Example of track-to-track crosstalk
• Crosstalk in flat cables
• Crosstalk reduction using a ground plane


8/ Field-loop coupling
• Calculation of loop voltage 
• Example of susceptibility 
• Magnetic field case 
• Twisting of conductors 


9/ Field-to-wire coupling
• Whip and dipole antennas
• Calculation of induced current
• Field reduction by ground plane


10/ Differential mode radiation
• Spectrum of a trapezoidal train
• Radiation from a small loop
• Example of radiation from a clock
• Reduction of loop areas
• Reduction of MD radiation


11/ Common mode radiation
• Radiation of a small whip
• Origins of common mode current
• Spectrum radiated in common mode
• Warning before radiation measurement
• Reduction of CM radiation


12/ Conduction protection
• Methods of low-frequency protection 
• Asymmetrical or differential connections
• Galvanic isolation
• Spark gaps, varistors, transzorb
• Methods of high-frequency protection
• Choosing a filter structure
• The three rules for installing mains filters
• Filtering low-level inputs
• Ferrite cores, choosing the number of turns


13/ Shielded cables
• Shielded and coaxial cables
• Transfer impedance
• Reduction effect of a shielded pair
• Or connecting a shielded cable
• Implementation of shielded cables


14/ Shielding
• Near field / far field
• Reflection and absorption losses
• Shielding effectiveness
• Choice of shielding material
• Necessity of openings
• Opening in a shield
• Electrochemical couples
• Conductive seals and spring fingers
• Plastic metallisation


15/ Design review
• EMC support for a project
• Mastery of initial choices
• EMC reviews