Spice & CEM

Goals

The objectives of the training Spice & CEM :

At the end of this training course, trainees will be able to adapt the SPICE simulation tool to EMC and extend its use beyond functional simulation.

• Master the basic analytical approach to understand orders of magnitude


• Know and master the correct tool settings for EMC


• Understand the libraries of active and passive components


• Be able to understand and model EMC couplings and non-linear effects


• Understand the modelling technique for sensors, couplers, EMC generators, shielded cables, filters, varistors, TVS, etc

Program

1 - Introduction
• EMC characterization of equipment
• EMC couplings in printed circuit boards
• EMC analysis method
• Common Mode / Differential Mode
• Mode conversion: CM/DM and DM/CM
• Use of decibels
• Time / Frequency relationship
• Spectral envelope of repetitive pulses
• Spectral density of a pulse
• GIGO


2 - LT Spice: Principles
• Circuit simulation software
• SPICE files 
• Adding a component to a library
• Calculation step: convergence and accuracy
• Time-domain simulations
• AC Sweep simulation


3 - Modeling Passive Components
• Modeling a resistor, capacitor, inductor
• Ladder network 
• Modeling an electrolytic capacitor
• Modeling a frequency-variable inductor
• Comparison of measurement / simulation of CM inductance
• Inductor with saturation and hysteresis: CHAN Model
• Modeling a pulse transformer
• Magnetic components and absorbent ferrites
• Modeling Varistors/Transzorbs/Transils/Spark Gaps


4 - Modeling Active Components
• Modeling an Op-Amp
• Slew Rate depending on the model
• PSRR, CMRR modeling
• Envelope detection simulation
• Detection of a JFET input stage
• Optocoupler envelope detection
• Effect of output impedance
• Simulation and effect of crossover distortion
• Structure of active filters
• Crossover distortion
• Stability on capacitive load
• Simulation of voltage dropouts (or: waste voltages)
• Simulation of incoherent noise spectral density 


5 - FFT
• Creation of standardized templates
• Time and frequency principles of an FFT
• Spectral folding (or: aliasing) 
• Spectral leakage
• Windowing before FFT calculation
• Ripple of an FFT
• FFT spectrum of centered and off-center pulses
• Flat top windowing for EMC emission measurements
• Automatic THD calculation
• Spectrum spreading by triangular modulation
• Spectrum spreading by optimal modulation
• Simulating a quasi-peak, RMS, or average detector


6 - Shielded Cables
• Transfer impedance of cables
• Principle of the reducing effect
• Transfer impedance and shielding effectiveness
• Shield termination
• Connection of shielded connectors


7 - Pulse Lines
• Fast logic and transmission lines
• Characteristic impedance and delay in lines
• Simulation of lines on Spice
• Reflection in Spice lines
• Specific features of SPICE transmission lines
• Modeling the Stub effect of a via


8 - Simulation of a Wire/Antenna using Lines
• Choosing line parameters for a wire
• Validating simulation of wire impedance
• Model of a loaded wire
• E.M.F. of a whip antenna
• Antenna factor of a whip antenna


9 - Simulation of Shielded Cables using Lines
• Transfer impedance of a single braid shield
• Simple model of a coaxial cable in CM + DM
• Reducing effect of a coaxial cable 
• Effect of a pigtail
• CM rejection by coaxial cable
• Transfer impedance of a double braid
• CM rejection in frequency by double braid


10 - Simulations of Asymmetry and Rejection of Cables
• Modeling of a 50 Ω to 100 Ω balun
• Asymmetry measurement on Spice
• Asymmetry of an isolated unshielded bifilar pair
• Localized asymmetry on a differential pair
• Asymmetry of an STP / UTP cable
• Impedance asymmetry / length difference
• CM rejection by asymmetrical pair
• CM rejection by shielded twisted pair


11 - Crosstalk
• Capacitive and inductive crosstalk on PCB
• Capacitance/mutual extraction from connector pins
• Reduction of the edge effect of a connector
• Effects of good pin distribution
• Line simulation to model crosstalk
• Crosstalk between natural lines and matched microstrips
• Effects of increased transition times
• Effect of a small mismatch
• Crosstalk on a highly mismatched line


12 - Conducted Emission
• Diagram and modeling of an LISN
• Model of the CM power line
• CM and DM filter impedance
• Modeling and insertion loss of a filter in DM and CM
• Asymptote method in energy conversion
• Common mode envelope generator
• Coupling and modeling of a CM converter
• CM emission simulation and filtering
• Differential mode envelope generator
• Coupling and modeling of a DM converter
• DM emission simulation and filtering
• Simulation of filtered CM and DM emissions
• Simulation of radiation coupling of a filter
• Time-domain simulations 
• Identification of critical loops in a Buck circuit
• Time-domain simulation of Buck disturbances
• Effects of loop inductance
• Effects of transistor selection
• Diode recovery
• PFC transient regime
• Simulation of specific rectifiers


13 - Radiated Emission
• Problem of radiated emissions
• Free space radiation from a CM cable
• CM current on coaxial cable induced by DM signal
• Effectiveness of a ferrite core on coaxial cable
• CM & DM simulation of perfect differential pair
• Asymmetry due to 1 mm length difference


14 - Conducted Immunity
• Difficulty in modeling common mode tests
• Simulation of induced lightning surge
• LF immunity of power supply according to CS101 / NCS01 / Section 18
• WF4 + WF5 generator according to MIL-STD 461G/DO-160
• Simulation of WF4/WF5 injection on a harness
• 61000-4-5 surge generator in DM and CM
• Shock wave generator according to standard 61000-4-5
• Modeling of BCI injection clamp


15 - Radiated Immunity
• Voltage induced by field-to-loop coupling
• Frequency-dependent field-to-loop induced current
• Time/frequency field-to-cable coupling 
• Time-domain effect of a pigtail
• Effects of IEMN and rejection by shielded cables 


16 Conclusion
• Spice modeling pitfalls
• SPICE hybridization – Wave models (EF, MoM, etc.)