Printed Circuit Board Design for EMC and Signal Integrity

Description

Printed circuit board layout is often the single most important factor affecting the electromagnetic compatibility of electronic systems. Boards that are auto-routed or laid out according to a list of “design rules” do not usually meet electromagnetic compatibility requirements on the first pass; and the products using these boards are more likely to require expensive EMC “fixes” such as ferrites on cables and shielded enclosures. Taking the time to ensure that components are properly placed and traces are optimally routed will generally result in products that meet all electromagnetic compatibility and signal integrity requirements on time and on budget.

Proper layout is particularly important in mixed-signal boards (boards with both analog and digital circuits). Minor mistakes in the layout of these boards can make the difference between a reliable product and a product with severe susceptibility problems. Recognizing poor design features early in a product’s development can save a lot of time and expense later on. This course stresses the fundamental concepts and tools that board designers must be familiar with to avoid electromagnetic compatibility and signal integrity problems. Students completing the course will be able to make good decisions regarding component selection, component placement, and trace routing. In addition, students will have the knowledge and tools necessary to design effective power distribution and grounding strategies for both digital and mixed-signal boards.

Course Outline

1. Introduction
   • Impact of Layout on Product Compliance and Cost
   • Examples of Good and Bad Board Layouts
2. Signal Routing and Termination
   • Tracing Current Paths
   • Concept of Least Impedance
   • When, Where and How to Terminate Signals
3. Identifying the Unintentional Antennas on a Board
   • Essential Elements of an Antenna
   • Cables and Enclosures as Radiating Elements
   • Board Structures that Potentially Radiate
4. Noise Sources and Coupling Mechanisms
   • Integrated Circuits as Sources of EMI
   • Parasitic Oscillations and Unexpected Noise Sources
   • ESD and Transient Susceptibility
   • Conducted, Electric and Magnetic Field Coupling
5. Circuit Board Grounding, Filtering and Shielding
   • Ground vs. Signal Return
   • To-Segment Or Not-to-Segment Planes
   • Filters that Work Above 100 MHz
   • Effective and Ineffective Shielding
6. DC Power Distribution and Decoupling
   • Effective Power Distribution Strategies
   • Choosing and Locating Decoupling Capacitors
   • Low-Inductance Capacitor Connections
   • Isolating PLLs and Other Sensitive Devices
7. Strategies for PCB Layout
   • Design Guidelines (Good and Bad)
   • Optimizing Component Placement
   • Stack-up and Routing Priorities
   • Common Problems that are Easily Avoided
8. Design Exercises and Examples

Course Instructor

	Dr. Todd H. Hubing