Explore the intricacies of signal reflections in PCB design through this comprehensive video lecture by Eric Bogatin. Delve into the differences between electrically short and long tracks, and observe simulations of various scenarios using specialized software. Gain insights into reflections on classic CMOS and standard boards, as well as electrically long tracks like DDR3/DDR4. Understand the distinction between 50 OHM impedance and resistance, and learn why reflections occur and their effects on signal integrity. Discover techniques to eliminate reflections, including termination methods and their impact on signal levels. With practical examples and in-depth explanations, master the concepts of signal reflections and their implications in PCB design.
When a Signal Hits the End of a PCB Track - What Happens? - Reflections by Eric Bogatin
Overview
Syllabus
Understanding reflections
Electrically Short vs. Long
The tool we are using explained
Simulating: Electrically short
Reflections on classic CMOS and standard board
Simulating: Electrically long e.g. DDR3 / DDR4
50 OHM impedance is not 50 OHM resistance
Simulating a buffer example
Why we get reflections
What happens when there is a reflection
Why reflection disappears
Frequency of ringing
How to eliminate reflections
Signal level change caused by termination
Source termination
Taught by
Robert Feranec
