Grounding & Shielding

 

Video course on DVDs:

Grounding and Shielding of Electronic Systems

How to Diagnose and Solve Electrical Noise Problems

A 15-Hour Video Presentation on DVD

Program Description

Most engineers and technicians using or designing electronic systems have not had formal training concerning grounding and shielding techniques.  Learning how to solve grounding and shielding 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 presents an organized introduction to fundamental grounding and shielding principles, clarifies troublesome terminology, and demonstrates many techniques for identifying and fixing electrical noise problems.  The principles will be described as concepts rather than theoretical equations.  The emphasis on concepts will make the course useful for people with a wide range of experiences.  Several interference mechanisms and shielding techniques are demonstrated.

Benefits

This course will help you to:
1. Use a logical procedure to diagnose and solve electrical noise problems;
2. Reduce the time and cost required to meet emission and susceptibility specifications;
3. Determine the optimum grounding technique for safety and low noise;
4. Recognize that all electrical noise problems are caused by four basic coupling mechanisms; and
5. Determine the correct connection for cable shields.

Course Outline and Learning Objectives
  • denotes key topics and * denotes learning objectives
Session 1: The Path of Least Impedance
  • Correctly identifying the entire current routing path
  • Importance of signal path self and mutual inductance
  • Demonstation-loop area controls inductance
* Explain why wiring inductance is more important than resistance
* Describe how current loop area is related to self inductance

Session 2: Electrical Noise Coupling Mechanisms
  • Conductive coupling
  • Magnetic-field coupling
  • Electric-field coupling
  • Electromagnetic wave coupling
* Describe the four noise coupling mechanisms
* List one key indicator for each mechanism

Session 3: Noise Coupling Equivalent Circuits
  • Simple equivalent circuit for each coupling mechanism
  • Parameters critical to noise reduction for each mechanism
  • Example problems
* Describe two ways to reduce each of the four coupling mecchanisms

Session 4: Why and How to Ground Electrical Systems
  • What is "electrical ground"
  • Reasons for grounding
  • Grounding analog and digital circuits
  • Reducing ground-loop noise
* Expain the two reasons for grounding
* Explain the difference between a grounding conductor and a routing conductor

Session 5: Signal Grounding Concepts and Examples
  • Ground kHz currents only once
  • Where to ground a signal?
  • Misuse of single-point grounding
* Explain when a signal should be grounded to an external metal enclosure
* Describe signal isolation techniques used to avoid ground loops


Session 6: How to Diagnose Noise Problems
  • Ringing, rounding and reflections
  • Demonstration - measuring noise
  • Influence of circuit impedance on noise susceptibility
* Describe one noise symptom for each coupling mechanism.
* Use the susceptible circuit impedance to identify the most likely coupling mechanisms.

Session 7: Impedance Balancing and Common-Mode Rejection
  • Common mode and differential mode
  • What does impedance balance mean
  • Demonstration - CM to DM conversion
* Recognize the importance of impedance balancing as a noise-reduction technique.
* Identify causes of circuit imbalance.

Session 8: Filtering Conducted Noise
  • Selecting the selecting the correct filter strategy
  • Types of filters
  • Influence of circuit impedance on filter configuration
  • Controlling shunt capacitor mutual inductance
  • Use of ferrite beads
* Explain when to use series blocking and shunt diverting filter techniques.
* Understand the problem with mutual inductance between input and output ports.

Session 9: Self Shielding - Low Cost Field Containment
  • The concept of self shielding
  • Self-shielding examples
  • Misuse of twisted pair
* Explain how self shielding works.
* Describe how self shielding can reduce the use of other shielding materials.

Session 10: Electric-Field Shielding
  • Demonstration: an electric-field coupling problem
  • Where to ground the shield on a twisted pair cable
  • Electric-field shielding examples
* List several circuit characteristics that help identify electric-field noise coupling.
* Explain how often and where to ground the electric-field shield on a cable.

Session 11: Magnetic-Field Shielding
  • Magnetic-field shunting and reflection
  • Demonstration: magnetic-field shielding
  • Problems with high permeability materials
* Identify the frequency ranges over which magnetic-field shunting and reflection are effective.
* Describe the difficulties with high-permeability shielding materials.

Session 12: Electromagnetic-Wave Shielding
  • Shielding against ESD and RF
  • 360˚ shield connections
  • Reducing leakage through seams
  • Dampening chassis resonances
* Explain why radiation is influenced more by the quality of the shielding connections than by grounding.
* Describe how to control radiation leakage through seams and openings in a metal chassis.

Session 13: Selecting the Right Cable
  • Desirable EMC properties of cables
  • Comparing coaxial and twisted-pair cables
  • Cable selection examples
* Explain how to evaluate cable alternatives given the noise-coupling mechanism and the signal bandwidth.

Session 14: Circuit Board Layout - Part I
  • Controlling trace inductance
  • Avoiding traces crossing gaps in the return plane
  • Connector placement to reduce emissions
  • DC power distribution
  • Sizing and locating decoupling capacitors
* Recognize trace layouts that have excessive inductance.
* Design more effective DC power-distribution busses.

Session 15: Circuit Board Layout - Part II
  • Component placement
  • Signal and power stackup alternatives
  • Grounding heat sinks
  • High-speed transmission lines
* Compare the placement of signals on outer layers versus signals between two planes.
* Determine which nets should be terminated as transmission lines.

Price Options
Single User--$1500
Multiple Users--$4500
Site License--$9000
(The site license allows the content to be placed on a company network at a single location.  The course content can then be accessed by all employees at that one location.)


To Order:
Contact Tom Van Doren at:
vandoren@mst.edu