DesignCon 2013 – being held this week in Santa Clara, Ca. – is normally considered as the technical conference of choice for specialists in signal integrity. But I think it is time to think about signal integrity as an issue about which everyone involved in embedded systems development needs to know more.
The reason is simple. Even though embedded systems developers – hardware or software – are focused mainly on the manipulation of signals in digital form, digital signals are nonetheless fundamentally analog in nature and are subject to a variety of effects such as noise, distortion, EMI, ESD and loss.
Over short distances and at low bit rates, signals can be transmitted with a relatively high degree of integrity. But unfortunately, in the era of high density nanometer scale integrated circuits on chip interconnect can often be in the tens of meters and operating at very high bit rates. And this is before the signals even get off chip. Over longer distances across a board and between boards in a system, through various mediums, numerous effects can degrade the electrical signal to the point where errors occur, and the system or device fails.
What were once simple wire paths on a board or in a system are now complex circuits of parasitic elements created from every transition the wire makes, from connectors to vias to solder pads.
Guaranteeing signal integrity is thus an activity that the embedded system designer must be actively involved – at all levels: electronics packaging and assembly, from internal connections of an integrated circuit, through the package, the printed circuit board, the backplane, and inter-system connections. Everyone needs to learn more about SI issues and how those problems occur and how the inter-relationships between these elements impact the total design.
In short, to be addressed effectively signal integrity must be a team effort and everyone needs to be speaking the same language.If you value the work you have put into your design, you owe it to yourself to learn at least the basics of signal integrity engineering. A good first step toward gaining more understanding of this crucial aspect of embedded systems design is to attend the DesignCon this week .
If you are not able to attend, get in touch with the SI specialist on your design team who attended and get a copy of the papers and presentations and read them over so you have a complete picture of the complexity of the problem.
A good second step is to keep track of developments in this area on web sites such as Embedded.com , where signal integrity at all levels has been an area of active interest for most of the last 20 years (See, for example,”Signal integrity permeates the design process” )
Some of the most recent articles, blogs, technical papers and webinars are included this week in the Embedded Tech Focus Newsletter on: “Designing for signal integrity, ” which among other things features an excellent introduction to the basics of signal integrity. In addition there a number of other articles from Embedded.com knowledge base that I recommend, including:
“Extending your reach with Serdes, ” a tutorial on how to use Serdes to deal with signal degradation and integrity issues relating to multigigabit backplane, trace and cable distortion.
”Accelerating SERDES simulation with Simulink model libraries,” on how to do top-down design of a SERDES model using MatLab's Simulink tool, and how it reduces design simulation times and improves signal integrity.
“Addressing EMI test issues in nextgen high density PCBs, ” which deals with signal integrity testing and EMI conformity challenges of next generation printed circuit board design and what factors should be considered when evaluating a PCB design tool.
“Capturing and Debugging System Crashes ,” which clarifies and explains the concepts, techniques, and logic analyzer tools that can be used to troubleshoot your embedded design for troubling signal integrity problems.
In addition, there are a range of other articles on signal integrity in a variety of industrial, communications, mil/aero applications, that I also found useful:
Becoming a hot commodity (if you're a signal integrity engineer) !
Using model-based design in signal integrity engineering
Enhanced triggering for verifying-debugging complex serial designs
Maximize high-speed signal integrity with the right cable choices
Accommodate DC-level mismatch in multigigabit serial data links
I look forward to working with the members of the embedded systems design community in developing additional content on issues relating embedded system signal integrity and reliability. I hope to hear from you with your ideas and proposals.
Embedded.com Site Editor Bernard Cole is also editor of the twice-a-week Embedded.com newsletters as well as a partner in the TechRite Associates editorial services consultancy. He welcomes your feedback. Send an email to , or call 928-525-9087.