-
- News
- Books
Featured Books
- design007 Magazine
Latest Issues
Current IssueBreaking High-speed Material Constraints
Do you need specialty materials for your high-speed designs? Maybe not. Improvements in resins mean designers of high-speed boards can sometimes use traditional laminate systems. Learn more in this issue.
Level Up Your Design Skills
This month, our contributors discuss the PCB design classes available at IPC APEX EXPO 2024. As they explain, these courses cover everything from the basics of design through avoiding over-constraining high-speed boards, and so much more!
Opportunities and Challenges
In this issue, our expert contributors discuss the many opportunities and challenges in the PCB design community, and what can be done to grow the numbers of PCB designers—and design instructors.
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - design007 Magazine
Estimated reading time: 1 minute
Beyond Design: Skewed Again
When skew needs to be adjusted, it is best done at either end of the differential pair. In this way, the coupling and signal quality of the remainder of the pair is maintained.
Differential signaling is a method of transmitting serial, high-speed, complementary signals down a pair of coupled transmission lines. The equal and opposite nature of the differential pair means that demand on the power distribution network (PDN) is less than for a similar, single-ended data path. And, since external interference tends to affect both signals equally, the noise is cancelled providing high immunity to common mode electromagnetic interference compared to single-ended transmissions. But that is assuming the pair are perfectly balanced and terminated correctly. Generally, on-die termination (ODT) compensates for this, which may otherwise have a significant impact on signal quality and power dissipation.
Differential skew refers to the time difference between the two single-ended signals in a differential pair. Any mismatch in delay (skew) will result in changing part of the differential signal power into common-mode power.
Differential skew has become a performance limiting issue for high-speed SERDES links. The operation of such links involves significant amounts of signal processing to recover clocks, reduce the effects of high-frequency losses, reduce inter symbol interference (ISI), and improve signal-to-noise ratio. Skew limits the bandwidth of these links, adds data-dependent jitter, and limits the possibility of equalizing links to compensate for high-frequency skin effect and dielectric losses.Read the full column here.Editor's Note: This column originally appeared in the June 2013 issue of The PCB Design Magazine.
More Columns from Beyond Design
Beyond Design: The Art of Presenting PCB Design CoursesBeyond Design: Embedded Capacitance Material
Beyond Design: Return Path Optimization
Beyond Design: Just a Matter of Time
Beyond Design: Design Success with IPC Standards
Beyond Design: Integrating AI Into PCB Design Flow
Beyond Design: Standing Waves in Multilayer PCB Plane Cavities
Beyond Design: Balancing Trade-offs for Optimal PCB Design