On the Minimization of PCB Differential Pair Skew or Its Effect

Wed. January 30| 2:50 PM - 3:30 PM | Ballroom F

Pass Type: 2-Day Pass, All Access Pass, Alumni All Access Pass

Track: 06. Applying Chip-to-Chip and Advanced PCB Design & Simulation Techniques

Audience Level: Intermediate

Session Type: Technical Session

Description: This paper presents two new methods for dealing with skew. Fiber-weave effect is minimized using a non-uniform differential pair. It consists of a hybrid combination of edge-coupled and broadside-coupled differential geometries. Traces are routed as "complementary twisted pairs". Skew results in fading at a precise frequency and its multiples. It is discovered that the effect of skew can be reduced by using multiple strongly coupled elements. An exact analytical solution is derived for the differential insertion loss of a link comprising two tightly coupled sections. Numerical results are validated using 3D EM field solvers.

Takeaway: Why is differential pair skew so important? Because it causes fading! One can either "cure" the disease, or its symptoms. The disease is predominantly caused by a non-uniformity in the substrate material. Here we show that it, or, its symptoms can be cured by using non-uniform transmission lines.


Syed Bokhari

Syed Bokhari

Technical manager of SI and EMC

Fidus Systems Inc

Role: Speaker