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

Real Time with… AltiumLive Europe: 21st-Century Tools Keynote

10/22/2020 | Pete Starkey, I-Connect007
Good morning, Europe!” Altium VP of Marketing Lawrence Romine said as he introduced the European edition of Altium’s PCB design conference—established as an annual must-attend event, but for 2020 presented in a virtual format. Pete Starkey brings you the details from AltiumLive Europe's opening keynote on 21st-century tools and what's coming in 2021.

I-Connect007 Editor's Choice: Five Must-Reads for the Week

10/09/2020 | Andy Shaughnessy, Design007 Magazine
It’s showtime! This past week, we saw quite a bit of news about virtual trade shows. It’s great to see show managers pivot from live, in-person events to virtual shows with only a few months to make it all happen. How would you like to be a show manager today?

Mentor and Z-zero Collaborate on New Stackup Tool

09/17/2020 | Andy Shaughnessy, Design007 Magazine
I recently spoke with Max Clark, business unit manager with Mentor, a Siemens Business, and Z-zero founder Bill Hargin about the newly formed partnership that resulted in a new stackup tool that Mentor is now selling worldwide. Fun fact: Hargin used to work for Mentor as part of the HyperLynx team, which now has an interface with Z-planner Enterprise. Talk about coming full circle.



Copyright © 2020 I-Connect007. All rights reserved.