High-Speed Noise and Grounding

More Black Magic with
Dr. Howard Johnson  

This two-day class focuses on mixed-signal applications involving high-speed digital electronics used in conjunction with sensitive analog circuits such as radio receivers, GPS devices and cell phones. This course addresses the critical issues of noise and grounding that are seen in many advanced signal processing applications today, including avionics, telemetry and guidance systems.

The motivation for this course is described in the somewhat tongue-in-cheek article: Digital Engineers Don't Believe in EMC.

Main Topics

Course Syllabus

Chapter 1: Principles of Mixed Signal Isolation

• Forms of Coupling
• Facts Necessary for Understanding High-Speed Noise and Grounding
• Mutual Inductance Matters
• Frequencies That Matter for Digital Signals
• Five Ways to Reduce Crosstalk

Chapter 2: Ground Bounce (SSO)

• In the presence of fast-changing magnetic fields you can only measure voltages between nearby points
• Use the shortest ground attachment possible on your probe
• Distributed nature of inductance
• BGA package crosstalk (SSO coupling) varies with pin separation, package height, and signal rise/fall time

Film: BGA Ground Ball Placement

• This 40 min. film presents the theory of SSO crosstalk in BGA packages with examples, giant scale models, and measured lab results.

Chapter 3: PCB Layer Stack

• The Path of Returning Signal Current
• Measuring Tiny Amounts of Crosstalk
• Differential Probing
• Stacking Connectors
• When to Segment the VCC Plane
• Moat and Drawbridge Construction
• Good High-Speed Practices for Big, Fat Boards

Chapter 4: System-Level Grounding

• Picture Frame Analysis
• Three Big Ideas For Isolation (i.e., Reducing the Impact of Stray Current)
• Capacitance Between Boards
• Interconnections Between Boxes
• Crosshatched Ground: To what degree does patterning affect…

Chapter 5: Clock-Related Noise Issues

• Unexpected Synchronization Difficulties: Points to Remember
• Do Terminations Reduce Emissions?
• In a differential link, skew creates a common-mode signal
• Planning ahead for jitter testing is the most important thing you can do to address jitter in your high-speed system architecture.

Chapter 6: Electromechanical Issues

• Board-to-board Connector Electrical Noise Performance
• Shielded Cabling Connectors
• Mechanical Issues: Key environmental parameters
• Trends in Interconnect Design
• Standards-Based Design
• Example of standards-based system: Firewire (IEEE 1394)
• Tin Whisker Alert

Chapter 7: System Test

• Eye Don't Like It
• Compliance Testing: An Interview with JP Miller, distinguished technologist at Hewlett Packard.
• Debugging Hardware
• Measurement Problems
• Personnel issues
• Practical System-Design Advice (Wrap-up)

If you need it, here is an even more detailed outline.

Who has participated in this workshop?

Originally developed for the clients in the military/avionics space, this workshop has been presented by Dr. Johnson for thousands of engineers in both public and private forums worldwide. Past participants represent a wide variety of organizations, including:

General schedule and registration