Impact of Serpentine Routing on Multi-gigabit Signal Transmission


Reading time ( words)

Abstract

This article discusses the impact of PCB serpentine routing on high-speed signal integrity in terms of impedance discontinuity, insertion loss and eye diagram opening and differential to common mode conversion for signal transmission at 1Gbps (i.e., lower-speed grade) and 10Gbps (i.e., higher speed grade). This investigation is performed using Keysight ADS.

Introduction

Serpentine is a technique to minimize skew or misalignment of differential pairs (Figure 1). The number of segments and intra-pair spacing of serpentining impacts the high-speed signal transmission. As the intra-pair gap is enlarged for serpentining, the characteristic impedance of the PCB trace in differential mode will rise, as governed by Equations 1 and 2. This leads to impedance discontinuity, signal reflection, and ultimately, attenuation. The signal attenuation is heavily dependent on the number of segments and intra-pair spacing of the serpentine. Besides impedance discontinuity, increasing the intra-pair spacing at serpentine segments also loosens the electromagnetic coupling within the differential signal pair, and eventually worsens the differential to common-mode conversion that weakens the immunity of the channel against common-mode noise or crosstalk.

To read this entire article, which appeared in the October 2018 issue of Design007 Magazine, click here.

Share

Print


Suggested Items

Todd Westerhoff on the Value of Solid Design Skills

01/21/2020 | Andy Shaughnessy, Design007 Magazine
Andy Shaughnessy recently caught up with Todd Westerhoff, product marketing manager for Mentor’s HyperLynx signal integrity (SI) tools. Todd discusses some of the challenges that he and his customers are facing and why good design skills have more influence on a PCB than any software tool.

The World of PCBs: Anything But Boring

01/17/2020 | Andy Shaughnessy, Design007 Magazine
Andy Shaughnessy had the chance to catch up with Megan Teta, CID+, product manager of design and education services at Insulectro. Megan explains why she’s excited to become more involved in training and why the world of PCBs is anything but boring, contrary to popular opinion.

Top 10 Most-Read Design News Stories of 2019

12/26/2019 | Andy Shaughnessy, Design007
As we move into 2020, we took a look back at the most popular Design007 news stories of the past year. Here for your enjoyment are the Top 10 most-read Design007 news items of 2019.



Copyright © 2020 I-Connect007. All rights reserved.