Getting started in signal integrity? check out the pdf copy of Chapter 1 from Signal and Power Integrity- Simplified, available for free download on www.beTheSignal.com
Today, signal integrity has become the limiting factor in all products operating at 200 MHz and above. This includes all communications products, servers, personal computer and even cell phones. Not paying attention to signal integrity in the beginning of a design means the product may not work at bring-up.
While the highest end applications- telecommunications, test and measurement, super computers, mainframes and servers have been in this regime for more than thirty years, mainstream consumer products have been sensitive to signal integrity effects for only about ten years.
At the dawn of the “mainstream signal integrity” era, before “social networking” was even imagined, there was the SI-List. Almost all signal integrity engineers, at one time in their career, have participated on this email distribution list, either posting questions, answering questions, participating in the debates or listening to the chatter.
Sixteen years ago, on May 16, 1994, the SI-List was born with 30 members on the charter email list.
Ray Anderson, then a recent convert to signal integrity from years as a microwave engineer, came up with the idea of an email discussion group to continue the question and answer period from the last day of a four day short course he had taken on signal integrity.
He had recently joined Sun Microsystems as a signal integrity engineer. His jump start into this new field was “Electrical Modeling, Simulation and Design of Electronic Packages”, taught by Raj Mittra, Paul Franzon and Jose Schutt-Aine in San Jose, CA on May 9-12, 1994.
“On the last day of class I said it would be really neat if we put together a mail list to pose questions and answers to continue the discussions. I went back to my office on Monday and hacked together an email list on the SPARC2 worskstation sitting in my office at Sun Microsystems with the thirty names from the class.”
Figure 1. Ray Anderson in his package characterization lab at Xilinx, where he is currently a senior engineer.
Sixteen years later, there are 4,000 members on the SI-list spread over more than 34 countries. The range of participants starts with novices and students in college and extends to world renown experts such as Scott McMorrow, Steve Weir, Istvan Novak and Todd Hubbing.
“The typical questions posed to the list today, are not that different from the early days,” Ray says. “Over the 18 years I’ve been in signal integrity, the technology has changed, but the physics hasn’t.”
The questions posed on the SI-list are an indication of the most confusing or controversial topics in signal integrity. Power distribution design (PDN) has always been a hot topic. How many and what value decoupling capacitors do I need on my board and where should they be placed are the most common questions asked, followed by what is the inductance of a via?
Questions range from general, open ended topics, such as which is better a VNA or TDR? to specific design questions about the timing delay between data and clock in the DDR3 JEDEC timing spec.
The hot topic these days include the frequency dependence of the dielectric properties of laminates and the use of S-parameters to describe interconnect performance including causality and passivity.
“When I started the list and saw it grow so fast, I had visions of herding cats. But, it has turned out to be remarkably well self managed. Peer pressure usually establishes the norms for behavior,” Ray says.
In addition to questions and technical discussion, it is also a bulletin board for announcements about upcoming webinar, seminars, short courses or job announcements. List etiquette discourages recruiters from posting job openings in the SI field, except by the hiring manager directly.
There are always those who abuse the list. However, over the 16 years of its existence, there have only been 12 individuals banned from the list. One of the biggest frustrations with long time participants of the list is with the same, fundamental questions being asked by “newbies.”
“If you are going to ask a question,” Ray advises, “do your homework first. Make an attempt to solve the problem yourself. Read some books, search the web and the list archives, then pose the questions. Don’t just try to get someone to do your work for you.”
To subscribe to the SI-List, go to : http://www.freelists.org/webpage/si-list
To view the archives of postings, go to: http://www.freelists.org/archive/si-list/