Course Abstract:

This course offers all of the EMI information you'll need-including design considerations at CAE and CAD levels-for you to provide a compliant radiation/susceptibility product. You'll examine ways to prevent common EMI/EMC problems regarding power supplies, cables, connectors, slots, discontinuity of ground planes and more. This two-day class will focus on EMI and RFI issues regarding PCBs, computers, analog designs and systems, along with relevant EMI regulations in the U.S., the European Union and Asia. Highlights include PCB radiation basics, radiation and bypass on PCBs, PCB radiation suppression techniques, grounding designs/filtering, crosstalk/termination, power and ground planes, antenna loops, spread spectrum clocking, and differential-mode and common-mode radiation.

Course Length: 2 Days

Who Should Attend?

• Digital logic engineers
• System architects
• EMC specialists
• Technicians
• PCB layout professionals
• IC designers
• IC package designers
• Application engineers
• Anyone who works with high-speed digital logic
• Anyone who works with any digital logic implemented in the submicron processes that are becoming standard in the industry
• Engineering managers
• Project managers

• EMI, Source, path and receptor - Why all three must be present to have an EMI problem.
• EMI regulations - standards for USA, Europe (EU), and Asia. The course text provides a detailed description of all the test requirements, equipment to conduct the tests and the governing bodies/committees that mandate the tests.
• Threats - RFI, ESD, Power Disturbances, Internal
• EMI Issues - Frequency, Amplitude, Time, Impedance Dimensions
• EMI Regulations - Commercial, Military, Avionics, Automotive, Medical, Communications
• Conducting an EMI Test - Pre compliance, Compliance Testing, and Post-Audit Testing. What is uncertainty and how does it affect the test plan?
• How the Tests Are Conducted - For all the following tests, the hardware instrumentation, the layout, the pass/fail criteria, and tips/techniques to pass the test will be covered. Also, the test site will be defined, i.e. OATS, screen room, anechoic chamber and TEM cell. The step-by-step sequence of how each test is conducted will be detailed.
• Conducted Emissions
• Radiated Emissions
• RF Immunity
• Conducted RF Immunity
• ESD
• Lightening
• Electrical Fast Transient
• Interference Coupling Mechanism - What is the near/far field, coupling modes, resonance and why are parts placement, proper terminations and grounding so important.
• RFI, EMI regarding PCBs, computers, analog designs, and systems
• Grounding designs/Filtering - Single ground, modified and multipoint grounding, which one should be used for your design.
• CM Radiation - Why is common mode (CM) the major problem versus differential mode (DM)?
• Antenna Loops - Why are antenna loops the major cause of radiated emission failures for PCBs?
• Basics of PCB Radiation - Why do both lumped and distributive (transmission lines [T.L.]) circuits radiate? Why does a high Q circuit radiate? How do you terminate a T.L. to minimize radiation? What about the capacitive load and why does it cause radiation?
• PCB Suppression Techniques - Terminations, filters, and devices - how are they used to suppress radiation?
• Design for Immunity - Watchdog timers, offensive/defensive programming, checksum, Hamming, and other techniques. How intelligent software helps pass immunity testing.
• Switching Mode Power Supplies (SMPS) - SMPS Chopping Frequency.
  • Why is it the major cause of conducted emissions?
  • Filters - Schematic configurations of harmonic filters.
  • What happens when transients/ESD hits the SMPS mains?
  • What are the immunity concerns?
  • What are screens and snubbers, and how it a transformer wound?
• Crosstalk - Inductive/capacitive, forward/backward - How does it occur? Why does it cause radiation and how is it minimized?
  • How to minimize PCB antenna loops. Do vias cause radiation?
• Power/Ground Planes - Splits, slots, moats, floats, drawbridge, how to design for minimizing emissions from power/ground planes. How to design for digital/analog (multibias) and single bias PCBs.
• Picket fences, the 20H rule and Cu fills - What can they do to suppress emissions?
• Ideal stackups to be EMC.
• Spread Spectrum Clocking - Why does it suppress radiated emissions? Under what conditions can it be used? Is there a better method?
• Bypass and Radiation on PCBs - Why use the 0201, Ycap and four terminal cap? Types of innerplane capacitance and does innerplane capacitance help with emissions?
• Interference Coupling Modes - Why does ground bounce cause differential and common mode noise and how does that cause emissions?
• Near/Far Field - What determines the breakpoint between them and what happens to the characteristic impedance at the breakpoint?
• Differential/common coupling modes and resonance - What are the quarter length resonant mode differences when the load impedance is very high versus very low?
• Analog circuitry - Transients, filtering, grounding and noise isolation. Opto couplers versus spin resistors; which is better?
• Cables/Connectors Interfaces, Filtering and Shielding
• Capacitive and Magnetic Shielding - What is the difference and how should the shield be tied to ground for either case?
• Slots - Why do they radiate and is the radiation through them predictable?
• Shield Grounding - How should shields be tied to ground to minimize circulation current?
• Cable Radiation - Radiation through the shield and at the connector bulkhead connection.
• Shielding Types - When do we use Cu and Al versus mu metal, steel, or permalloy?
• Transfer Impedance - What is it? Why is it detrimental to shielding, and how is it minimized?
• Shielding Connection - Leakage - How to design a non-emission connection of a connector to a bulkhead.
• Loss of Ground Plane in Cables - Why does it cause crosstalk, radiation, reflections and propagation delay?
• Cables Configuration - What shielding/grounding techniques should be used to minimize crosstalk and radiation?
• Antenna Loops with Cable Connections - Why do shielding pigtails cause emission non-compliance?
• High-Speed Connectors - How are they configured to minimizie skin effect, dielectric loss, crosstalk, and radiation?
• Filtering - Types of filters, their attenuation capability and how should they be mounted?
• Shielding vs Filtering - Cost tradeoffs versus attenuation capability -When should either or be used?
• Using Ferrites - Amperes Rule - Why do they work so well for both DM and CM?
• Filtering Mains Supply - Using capacitors, chokes, and torroids. Filtering both DM and CM noise.
• Using Transients Suppressors on Mains and I/O lines - Where should TVSSs, Spark Gaps, Varistors and Zeners be used.
• Radiation Through Shields - Current density versus skin depth, incident versus reflected fields

Recommended Prerequisites:

This course is for anyone who has worked with today's ICs, high-speed designs and PCB layouts. No advanced math is required though attendees will find it helpful to bring a scientific calculator to the course. The course is presented at a technical level that will provide experienced designers with information to design and layout a high speed PCB including designing so that it meets Signal Integrity (SI) & EMI.

Supplied Materials:

Included in the class will be a copy of "EMC for Product Designers" by Tim Williams, and 170 pages of comprehensive course notes.