Grounding and Shielding of Electronic Systems

This course has been cancelled due to a family emergency.

(How to Diagnose and Solve Electromagnetic Interference and Signal Integrity Problems)

March 24-25, 2015  |  St. Louis, Missouri
A 2-day interactive lecture with demonstrations

Emeritus professor at Missouri S&T and founding member of the Electromagnetic Compatibility Laboratory, Grounding & Shielding plus Circuit Board Layout

Presented by Dr. Thomas Van Doren
Professor Emeritus of Electrical and Computer Engineering
Electromagnetic Compatibility Laboratory
Missouri University of Science and Technology

Email: vandoren@mst.edu
Phone: 573-578-4193

Course Description

Most engineers and technicians using or designing electronic systems have not had formal training concerning grounding strategies, shielding options, diagnostic procedures, and noise reduction techniques. Learning how to solve electromagnetic interference and signal integrity problems on the job can be very expensive for the employer and frustrating for the engineer. Most of the electromagnetic and circuit principles involved are simple. However, the complexity of many systems masks the logic and simplicity of possible solutions.

This course treats signals as currents; explains fundamental grounding, shielding, and signal routing principles; clarifies troublesome terminology; and demonstrates many techniques for identifying and fixing electrical interference problems. The principles will be described as concepts rather than theoretical equations. The emphasis on concepts will make the course useful for people with technical experience ranging from beginner to advanced designer. Since many noise emission and susceptibility problems are related to the mechanical design of systems, mechanical engineers and technicians can benefit from attendance. Several interference mechanisms and shielding techniques will be demonstrated.

The course will focus on controlling interference and signal integrity problems at the ‘systems level’ involving both analog and digital circuitry at frequencies ranging from DC to GHz. There will be some discussion of printed circuit board layout EMC issues, but most of the examples will involve multiple circuit boards in multiple chassis interconnected by a variety of cable types. Nearly all of the basic concepts presented and demonstrated can be used at either the integrated circuit level, the printed circuit board level, or the system level.

Course Benefits

This course will help engineers and technicians to:

  • Control both the outgoing and the returning path of signal currents
  • Understand and implement the ‘self-shielding’ technique
  • Use logical procedures, more than ‘trial-and error’, to reduce noise problems
  • Improve the signal integrity of high-speed digital waveforms by reducing ringing, reflections, and crosstalk
  • Reduce the time and cost required to meet radiated and conducted emission and susceptibility specifications
  • Determine the optimum grounding technique for both safety and low noise
  • Recognize that all electrical interference problems are caused by only four basic coupling mechanisms (conducted currents, magnetic fields, electric fields, and electromagnetic waves)
  • Determine the correct connection for the shield on a twisted pair cable

 

Course Topic Outline

FIRST DAY

1.  Introduction
Misconceptions that cause electromagnetic interference
Treat signals as currents
The ‘self-shielding’ concept

2. Current Routing and Least Impedance    
Correctly understanding wiring self-inductance┬┐  
DEMO: What is the path of least impedance? ┬┐  
Controlling the current return path

3. Interference Coupling Mechanisms
Review of the 4 electrical energy coupling mechanisms
Key identifying characteristics of each mechanism
Ways to recognize the dominant noise coupling mechanism
Equivalent circuit for each coupling mechanism

4. Field Containment, Bandwidth, Balance and Resonance
Routing to provide field containment by self-shielding
DEMO: Magnetic field emitted by a coaxial cable
Relating bandwidth to the transition time of a pulse waveform
Common mode currents and the importance of impedance balance
Resonances in lumped and distributed circuits
DEMO: Predicting and reducing resonances

5. Grounding for Safety and Noise Reduction
The correct reasons for grounding
Signal routing is not the same as signal grounding
Characteristics of a ground structure
Safety grounding examples
Single point grounding versus a ground grid
Avoiding kHz ground loops
Grounding strategies for mixed signal analog and digital circuits
How to ground internal signals to a metal chassis to reduce susceptibility and emissions

SECOND DAY

6. Interference Diagnostic Techniques
Diagnostic analysis and measurement tools
How to determine the dominant noise coupling mechanism
The influence of circuit impedance on noise coupling
Noise diagnostic measurement techniques
Using current, electric-field and magnetic-field probes

7. Filtering to Reduce Conducted Noise
Current blocking and diverting strategies
Types of filters
Differential mode and common mode filtering techniques
Reducing shunt capacitor mutual inductance
Effective GHz filtering techniques
When to use ferrite beads

8. Field Containment Using the Self Shielding Principle
The low cost and wide bandwidth approach
Signal routing provides the containment
DEMO: Magnetic field emitted by a twisted pair compared to a coaxial cable
Example misuses of twisted pair cable
Some electric field self-shielding examples

9. Reducing Capacitive Coupled Noise
DEMO: Capacitive shielding example
Capacitive noise reduction options
DEMO: Where to connect the shield on a twisted pair cable

10. Reducing Inductive Coupled Noise
Reducing mutual inductance
Eddy current magnetic shielding using good conductors
Magnetic flux shunting using high permeability
DEMO: Magnetic shielding effectiveness of various metals

11. Electromagnetic Wave Shielding
Skin effect and electromagnetic field containment
How to contain electromagnetic energy inside a metal enclosure
Making cable shields effective at GHz frequencies
Sizing air flow openings
Controlling common mode currents that cause radiation
EM field containment is more important than grounding


About the Instructor
Dr. Tom Van Doren is Professor Emeritus of Electrical and Computer Engineering at the Missouri University of Science & Technology (Missouri S&T) and a founding member of the Electromagnetic Compatibility Laboratory. He has conducted research and education in electromagnetic compatibility for the past 30 years. More than 19,000 engineers and technicians from 105 companies and government agencies in 15 countries have attended his “Grounding and Shielding” and “Circuit Board Layout” courses. Currently, 8 US and 9 foreign corporations are sponsoring EMC related research projects at the Missouri S&T EMC Laboratory. Dr. Van Doren has received two outstanding teacher awards from Missouri S&T (formerly University of Missouri-Rolla) and the Richard R. Stoddard award from the IEEE EMC Society for contributions to EMC technology and education.  He is a Life Fellow of the IEEE and an Honored Life member of the EMC Society.  Much of his professional work has been devoted to helping engineers and technicians understand, diagnose, and reduce signal integrity and electrical interference problems. He has been very happily married to his ‘angel’ Lana for over 54 years.


Location & Parking

The course will be held in St. Louis, Missouri, on the University of Missouri-St. Louis (UMSL) campus in room 335 of the Social Sciences & Business (SSB) Building.  The SSB Building is building number 11 near West Drive Road on the following map:

http://www.umsl.edu/files/pdfs/north-campus-map.pdf 

Free parking is available in the West Drive Garage South, building number 52 on the map, located along West Drive just south of the Social Sciences & Business building. Parking is free because the UMSL campus is on spring break during the week of the short course. Please ignore all of the signs that indicate that parking is reserved and restricted. Free visitor parking is allowed in this garage only during this spring break week.


Cancellation Policy
The University reserves the right to cancel its programs in the event of insufficient registrations, instructor illness, severe weather, or natural disaster. In the event of cancellation, registrants will be notified immediately and all fees will be returned in full. Persons wishing to cancel their registration must do so by close of business on March 13, 2015. No refunds will be made after this date.  Substitutions may be made at any time.