Conception CEM perfectionnement (Module 2)

Goals

The objectives of the training Conception CEM perfectionnement (Module 2) :

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 behaviour of components and recommendations for associated routing.

The aim of this training course is to:

• Master initial design choices


• Master the EMC of components


• Understand the effects of transmission lines


• Master the implementation of fast connections


• Understand and adapt LF and HF protection solutions


• Master the choice of shielded connections and their implementation


• Optimise shielding solutions...

Program

1-Introduction: Reminders
• EMC mastery in the company
• Project EMC follow-up (1)
• EMC analysis method
• Project EMC follow-up
• Emission tests: summary
• Orders of magnitude in immunity
• Common mode and differential mode
• Transformation of Common Mode into Differential Mode
• Spectral envelope of repetitive pulses
• Spectral density of a pulse
• Insulating or conductive environments
• EMC couplings in boards
• Conductor impedance
• Reduction of track inductance by geometry
• Resistance and reactance of a short pair
• Calculation of a loop voltage
• Current collected by a dipole
• Resonant circuits
• EMC formulas
• EMC acronyms


2-Characteristics of passive components
• Resistor impedance
• Single-pulse withstand of a resistor
• Impedance of non-polarized capacitors
• Extraction of capacitor values
• Measurement of dielectric absorption
• Various causes of capacitance change
• Inductor impedance
• Extraction of inductor values
• Real and imaginary magnetic permeability
• Beware of high µ ferrites
• Choosing a ferrite bead
• Measurements or modeling?


3-Characteristics of active components
• Component noise
• Principle of envelope detection
• Frequency response of an Op Amp
• JFET input stage detection
• Op Amp envelope detection: evaluation
• Output impedance of an Op Amp
• Beware of the structure of active filters
• Effect of output impedance
• Beware of exposed capacitive feedback
• Immunity of a digital isolator
• Risk of transistor oscillations in UHF
• Static voltage noise margins
• Dynamic margin of logic
• Oscillations of a MOS gate
• The latch-up phenomenon
• EMC of sample-and-hold circuits
• Integrated protection against ESD


4-EMC of switching circuits
• The 5 disturbances of a converter
• Identification of critical loops in the Buck
• Temporal simulations of the Buck
• Diode recovery
• Reduction of disturbances
• Emerging Components
• Miller effects of power MOSFETs with SJ
• Parallel connection of transistors
• Distortion of the PWM signal at the Driver input
• Sources of problems in radiated emission
• Role and calculation of "snubbers"
• Ensuring the immunity of a converter


5-Transmission lines
• Line: equivalent schematic
• Characteristics of typical lines
• Practical measurement of line impedance
• Signal shape: total mismatch
• Signal shape: Matched generator
• Series or parallel matching
• Losses in a line
• Measurements and coaxial cables
• Termination of fast lines


6-Crosstalk
• Capacitive and inductive crosstalk on PCB
• Track-to-track capacitance: microstrip
• Crosstalk on printed circuits
• Measurement of capacitive crosstalk
• Measurement of crosstalk in a connector
• SPICE model of a straight connector
• Effects of good pin distribution
• Crosstalk in loose coupling, matched lines
• Progressive and regressive crosstalk


7-Internal EMC of Integrated Circuits (ASICs)
• Evolution of semiconductor engraving size
• Noise and couplings of ASICs
• Noise budget
• Origins and effects of dI / dt
• Calculation of the number of Vcc / 0 V pairs
• Clock distribution
• Sizing of output drivers
• Beware of "pin-to-pin compatible" packages


8-Filters
• Transfer function and insertion loss
• Insertion loss of a power filter in CM and DM
• Frequency response of a 2nd order low-pass filter
• Damping of the L-C resonance
• Damped resonant pulses
• Pulse filtering
• Responses of various low-pass filters
• Impulse responses of low-pass filters
• Beware of filtering a digital signal
• Filtering of sensors / power supplies


9-EMC of interfaces
• Transzorb: Peak Power Curve
• Transzorb voltage and current
• Overvoltage protection by varistor
• Active protection at power input
• Immunity of a non-isolated mains regulator
• Schematics and protection levels of serial communications
• Maximum leakage capacitance of ESD protection
• Selection of ESD protection
• Protection of analog I/O
• Protection of TOR, Transistor, Relay type I/O
• Protection of USB, CAN, and I2C
• Protection of Ethernet links
• Recommendations for Ethernet
• Protection of Audio/video
• Protection of LCD interfaces
• Protection of power supplies
• Protection of storage interfaces
• Integrated protection in the connector
• Arrangement of A/N zones and ground planes
• Grounding of external connectors
• Filtering of Inputs / Outputs


10-Printed Circuit Boards (PCBs)
• Impedance of a copper sheet
• Optimal distribution of PCB layers
• Return current in a ground plane
• Impedance of 0 V planes
• Effects of slots in a ground plane
• "Hidden" impedances of a connector
• The 3 types of guard ring (or track)
• Beware of near-field radiation
• Schematic, component placement and routing symmetry
• Tracing of fast signals
• Tracing for DDR memories
• Signal integrity in the PCB
• Recommendations for Inputs/Outputs
• PCB layer stack-up


11-Cables and connectors
• CM rejection at low frequency by isolation
• CM LF rejection with a differential input
• Differential asymmetry by phase shift
• Asymmetry of input filters
• Types of shielded cables
• Symmetry parameters of a differential line
• Longitudinal conversion loss (LCL)
• UTP/STP: CM to DM conversion
• Beware of pair asymmetry
• Measurement of pair asymmetry
• Typical pair asymmetry
• Balun asymmetry
• Asymmetry in 100Mbps Ethernet link
• UTP or STP: immunity calculation
• Principle of the reduction effect
• Simple measurement of the reduction effect, Zt, and shielding effectiveness
• Transfer impedance of connectors
• Importance of chassis grounding
• Reduction effect of a shielded pair
• Transmission of low signals


12-Radiated emission
• Clock emission
• Addition of the field from multiple clocks
• Reduction of harmonic richness
• Clocks with spectrum spreading (SSC)
• Radiation from the power cable
• Radiation from external cables
• Radiated emission of 2 superimposed signals
• Pre-qualification of a radiation measurement
• Analysis of CM current from 30 to 80 MHz
• Use of near-field probes


13-Shielding
• Steps for developing a shield
• Current circulation
• Criticality of leaks
• Excitation of I/O cables by near leakage
• Shielding attenuation of a slot
• Attenuation calculation of an undamped box
• Attenuation calculation of a well-damped box