Eric Bogatin's Blog: What I Learned This Month

DesignCon 2010 is right around the corner. It will be a busy time for all. As you set your schedule for the fours days of the show, be sure to add these events to your list:

Visit beTheSignal.com at booth #319. You’ll want to pick up a mug, an Appendix A -pocket guide to signal integrity design guidelines and, of course, some chocolate! Stop by and meet Susan and Laura. And I may have copies of my science fiction book, Shadow Engineer, on sale.

Monday, Feb 1, in the Theatre, I will present a 3 hour education forum, “Practical Magic: Signal Integrity Problems Disappear with the Right Tools“. My Agilent buddies and I will be showing about a dozen demos of some really cool hardware and software tools that I think should be in every signal integrity engineer’s tool box. check out my youtube video!

Tues, 8:30 am, I will present a paper “Frequency Dependent Material Properties: So What?”, with Don DeGroot, Sanjeev Gupta and Colin Warwick. If you are wondering about all the hype associated with “causal material properties” and want to know how does this apply to me, you’ll want to check out this talk.

Tues, 9:20, my colleague, Paul Huray, will present, “Impact of Copper Surface Texture on Loss, a Model that Works.” There’s a lot of buzz these days about rms roughness of copper. Come hear Prof Huray explain it’s really the surface texture of the copper, not just the rms roughness, that affects the extra losses from rough copper. You may find, as I discovered, that “everything you know about current and signal propagation is wrong.” Come hear the right way of thinking about how signals really propagate on interconnects.

Tues, 3:45 pm, I will participate on a panel discussion, “Science Fiction…is it really fiction?” This has got to be one of the more fun events at DesignCon, at least for me. I get to share the panelist table with Gentry Lee, famed co-author with Aurthur C. Clark of the Rama series, among other books, and noted scientist at JPL. We will talk a little about our visions of the future and open up the floor to discussion. Rumor has it, some of us might have books available for a book signing!

Wed 8:30 am. If you missed my education forum on Monday afternoon, you can catch it again on Wed morning.

I’m exhausted already, just writing about the exciting happenings at DesignCon 2010. See you there!

what’s new on beTheSignal.com:
Spring Institute of SI Training Classes now open for registration
Two No Myths Allowed webinars available for free viewing

Henry Ott is one of the gurus of EMC and noise control. After retiring from a distinguished thirty year career at Bell Labs, Whippany, he started a new company to focus on EMC education and consulting. For years, he has shared his practical expertise in electronic circuit design with the rest of us.

I first learned about correct cable shield termination for low noise design from his classic book, Noise Reduction Techniques in Electronic Systems, which he wrote in 1976. If you missed this classic of EMC design, it’s not too late.

His latest book, Electromagnetic Compatibility Engineering was just published by Wiley in 2009. While it includes much of the content of his first book, it’s been updated and more than half the book is brand new information.

I recently had a chance to chat with Henry about his book and about splitting planes and stack up design. The interview is part of the Shaughnessy Report on PCBDesign007.

“When is it appropriate to split ground planes?” I asked him.

“Never split ground planes unless you absolutely have to,” Henry said. “You have to have some external reason, not because you’re just laying out a board; for example, like a low leakage application in medical applications.”

“If you split ground planes and there is no compelling reason, the performance could be worse. I often fix problems my clients have by making the ground planes solid. 98% of the time, tie all the grounds together with a solid ground plane.”

An entire chapter of his new book is devoted to recommendations for circuit board stack ups. He evaluates 1, 2, 4, 6, 8, 10 and even 12 layer stack-ups to analyze the tradeoffs. There is sometimes more than one stack up that will work, but some might have higher performance margins than others. To select the best stack up for your application, you have to know the criteria for what is “better”. He offers six considerations:

1. a signal layer should always be adjacent to a plane
2. signal layers should be tightly coupled to their adjacent planes
3. power and ground planes should be closely coupled together
4. high speed signals should be routed on buried layers and located between planes
5. multiple-ground planes are very advantageous
6. when critical signals are routed on more than one layer they should be confined to two layers adjacent to the same plane.

If you work in signal integrity or EMC design this is a must have book. It has something for everybody.
 
One of the features that distinguishes this book from many others on the same subject is the inclusion of questions at the end of each chapter. While this of itself is nice, even better is that the answers are in the back of the book, in appendix F.

For example, question 12.8 is, “If a small circular and a small rectangular loop both have the same area and carry the same current at the same frequency, which will produce the greater radiated emissions?”

For the answer, you’ll have to check Henry’s book.

I recently had a chance to don a pair of LCD shutter glasses and stare into a synthesized 3D image that popped out of the screen at me. Cascading colors flowed around obstacles. I could move my head around and see how the pattern of colors moved in and around the objects in the foreground.

No, this wasn’t a scene I witnessed in Avatar, which I also viewed in 3D IMAX, it was a demo of Agilent’s new 3D glasses incorporated in an upgrade to their popular Momentum field solver suite. I had a chance to sample the new 3D vision system at the FPGA Camp in San Jose on Nov 11, 2009. Wow! Pretty darn cool!

Tightly coupled into the Agilent’s ADS simulation environment are Momentum, which does 2.5 D full wave simulations and EMPro which does 3D full wave simulation. While both of these tools can show 3D perspectives of the static or dynamic, electric or magnetic fields or currents in and around conductors, the simulations seem to come alive when viewed in true 3D.

To make this possible, Agilent has teamed with Nvidia to leverage their high end GPUs for the visual processing. The 3D images are generated by projecting on the monitor an image for just the right eye, while synchronized with the opened right eye shutter on the LCD glasses, and then projecting the image for the left eye.

The frame rate is high enough so that you don’t perceive the flicker, but see the screen in true 3D, giving the sense of having the object, and its field distribution, projecting in front of the screen. I suppose the next step is to incorporate a 3D mouse pointer and be able to move it around to interact with the 3D environment.

If you want to learn more about this novel imaging feature, be sure to check out the webinar Agilent is providing on Jan 21, 2009. You can sign up at this link.

I can’t wait to find the right demos to use for my upcoming live classes. One of these days soon, if I hand you a pair of LCD glasses when you walk into the room, you’ll know what to expect.

In addition to social networking, the web has enabled and revolutionized open sourced activities.

Linux started its life as an open source operating system, and has evolved into dozens of variations like Ubuntu. Wikipedia is now a top rated, open source information reference. Even astronomy and astrophysics research has entered the open sourced arena with the Galaxy Zoo project.

As an example of “online introspection,” Wikipedia states, “A main principle and practice of open source software development is peer production by bartering and collaboration, with the end-product (and source-material) available at no cost to the public.”

This is exactly the principle behind the FPGA Camp, an example of an open source conference. Vikash Rungta, a principle organizer, offered his motivation for the conference: “I love FPGAs and I wanted to get other FPGA people together to talk about FPGAs.” FPGAs, of course, stands for Field Programmable Gate Arrays.

Vikash has worked with FPGAs for more than 12 years, at start ups, at Cisco and now most recently at Infinera Corp. He sees FPGAs as sometimes an orphan topic at conferences like DAC and IEEE programs.  He wanted to attend a conference that focused just on FPGAs. When he couldn’t find one, he started one of his own.

His idea is to have an evening gathering once a quarter, free to all attendees, with highly rated speakers, food and refreshments and lots of opportunity to mingle, network and talk shop with other FPGA designers.

Amolok Badesha, an application engineer with Agilent Technologies, was one of the organizers of the first event, held on Aug 26, 2009. He and Vikash put the whole evening program together in less than two weeks just talking to friends. They arranged a room at Juniper Networks, asked a few vendors to pay for food and invited six experts to speak.

Salman Jiva of Altera, Steve Weir of Teraspeed and Marty Jain from Lattice were some of the speakers at the first event. This “Camp” focused on High Speed Serial Interfaces: Protocols, IPs and Devices. Once word got out to the design community, the free conference was quickly booked to capacity with 140 engineers.

The next event was held on Nov 11, 2009 at the Agilent Technologies auditorium. A dozen vendors had table-top booths and more than 150 engineers attended. I was one of the speakers and talked about “How the board will screw up your beautiful transceiver signals, and what you can do about it.”

A copy of the handouts of my talk can be downloaded from beTheSignal.com, and subscribers can view a recording of my lecture. You can catch an interview I gave Vikash which is posted on the FPGA Camp web site and on Youtube.

Vikash’s plan is to conduct these open source, low overhead, free conferences once a quarter. The organizers are all volunteers, the facilities are donated, the speakers do it for the opportunity to share and the vendors pay for the food and refreshments.

Where does the energy come from that drives these sorts of open source events? As Vikash says, “I do it for the passion. I love all things about FPGAs.” He sounds like an FPGA evangelist.