Grounding and Shielding of Electronic Systems

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

A 2-day Lecture/Demonstration Presentation by Dr. Tom Van Doren
Professor Emeritus of Electrical & Computer Engineering
Electromagnetic Compatibility Laboratory
Missouri University of Science & Technology
vandoren@mst.edu          573-341-4097

Course Description

Most engineers and technicians using or designing electronic systems have not had formal training concerning grounding and shielding 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 a wide range of experiences.  Several interference mechanisms and shielding techniques will be demonstrated.

Some of the Course Benefits

This course will help engineers and technicians to:

  • Use logical procedures, more than ‘trial-and error’, to reduce noise problems;
  • Improve the signal integrity of high-speed digital waveforms;
  • Reduce the time and cost required to meet emission and susceptibility specifications;
  • Determine the optimum grounding technique for both safety and low noise;
  • Recognize that all electrical interference problems are caused by four basic coupling mechanisms (conducted, magnetic fields, electric fields & electromagnetic waves); and,
  • Determine the correct connection for the shield on a twisted pair cable.

Grounding and Shielding of Electronic Systems
Course Outline

 

FIRST DAY

1.  Introduction

2. Current Routing & Least Impedance
   Understanding wiring inductance
   DEMO: Path of least impedance
   Controlling the current return path

3. Interference Coupling Mechanisms
   Review of the 4 coupling mechanisms
   Ways to recognize the dominant mechanism
   Equivalent circuit for each mechanism

4. Field Containment, Bandwidth
      Balance & Resonance
   Routing to provide field containment
   DEMO: Fields emitted by a coaxial cable
   Relating bandwidth to transition time
   CM currents and impedance imbalance
   Resonances in lumped & distributed circuits
   DEMO: Predicting & reducing resonances

5. Grounding for Safety and Noise
      Reduction
    Signal routing is not the same as grounding
    Characteristics of a ground structure
    Safety grounding examples
    Single point versus a ground grid
    Avoiding kHz ground loops
   Grounding analog and digital circuits
    Grounding signals to chassis for RF & ESD
         immunity and to reduce RF emissions

6. Interference Diagnostic Techniques
    Diagnostic analysis & measurement tools
    How to determine the dominant mechanism
    The influence of circuit impedance
    Diagnostic measurement techniques
    Using current and E & H field probes

SECOND DAY

Review of First Day

7. Filtering to Reduce Conducted
      Noise
    Current blocking & diverting strategies
    Types of filters
    CM and DM filter techniques
    GHz filtering techniques
    Reducing capacitor mutual inductance
    When to use ferrite beads

8. Field Containment Using Self
      Shielding
   The low cost & wide bandwidth approach
    Signal routing provides the containment
    DEMO: Twisted pair versus coaxial cable
    Misuses of twisted pair

9. Reducing Capacitively Coupled
      Noise
   DEMO: Capacitive shielding example
    Capacitive noise reduction options
    DEMO: Shield connection for twisted pair

10. Reducing Inductively Coupled
        Noise
   Reducing mutual inductance
    Eddy current shielding
    Magnetic flux shunting
    DEMO: Magnetic shielding options

11. Electromagnetic Wave Shielding
   Skin effect & RF containment
    Making cable shields effective at GHz
    Sizing air flow openings
    Controlling CM currents
    EM containment is more important than
         grounding

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

Cost and Scheduling

The total 2010 cost for the 2-day “Grounding and Shielding” course is $19,800, for a maximum of 35 participants.This price includes all travel expenses in the continental US and 35 copies of the course notes. Please email vandoren@mst.edu or call 573-341-4097 Tom Van Doren to schedule an in-house presentation.

Cost and Scheduling

Fees:
$19,800
maximum of 35 participants

Registration Contact:
Dr. Thomas Van Doren
Missouri S&T
Electrical & Computer Engineering
EMC Lab
Rolla, MO  65409
Phone: 573-341-4097
Email: vandoren@mst.edu