How did you get into electronics/ engineering and when did you start?

When I was about ten or eleven, I read a biography of Alexander Graham Bell and got inspired to experiment with telephones. There was this army surplus store not far from where we lived which had a lot of surplus electronic gear. I managed to save up enough money to buy a couple of push-to-talk handsets. After experimenting with them for a while with a lantern battery and lamp cord wire, I finally found a way to get them to work. That’s when I knew I wanted to learn more about electronics and figure out how other things worked.

Can you tell us about your career at Nortel? What did you work on?

My career with Nortel started back in the winter of 1976. I spent the semester working as a co-op student at Bell Northern Research (BNR) in Ottawa, Canada on the first Digital Multiplex Switch called DMS-1. It was the R&D organization jointly owned by Bell Canada and what was then called Northern Electric. The name had changed over the years until it finally ended up as just Nortel.

After I started full time in the spring of 1977, I worked on T1/T1C digital line repeaters. During that time, I learned a new skill in the art of PCB layout and the PCB fabrication process. It was also the time when I invented a unique electrical option switch which later was patented.

Throughout the 1980s I worked on a variety of projects as a digital hardware designer. The first board I designed was a fault-locate/order-wire card that was used on the next generation DMS-1 Urban platform. In 1985, I joined the digital multiplex switching division (DMS). I was responsible for designing a retrofit hardware system to facilitate in service cross-over from the older generation DMS100 to the new Supernode switch platform it was replacing. I also took over the design of the computing module backplane.

By the early 1990s, my focus was mostly on backplane design for new platforms. In 1995, a new project, XACORE was starting out to replace the computing module shelf of the DMS Supernode. I was instrumental in the design of an innovative high speed midplane utilizing non-contact, point-multipoint technology to achieve a multipoint-multipoint data bus architecture. The high speed data bus was later patented.

By the end of the 1990s through to 2009 my career gravitated towards high speed signal integrity and point-point serial link backplane architecture designs. In addition to being the backplane architect for many key platforms at Nortel during that decade, I also lead a team of signal integrity engineers from within the Passport division from 2001-2003. One of the most successful backplanes I designed during that time was for Passport 15K/20K multi-service switch platforms.

In the spring of 2009, I was forced to leave, after 32 years service, due to Nortel filing for bankruptcy protection in January 2009.

You mentioned something about a non-contact technology. Can you tell us more about that?

The non-contact technology actually relied on controlled electro-magnetic coupling, or simply crosstalk, to effectively couple the transmitted signal onto the pins of the respective circuit packs. Each card on the shelf would broadcast their data on their own set of differential pairs. As the differential pairs passed through the connector field of each slot, a small trace about an inch long, connected to the respective receiver pin, was routed in parallel to the trace as it passed by; effectively edge-coupling the signal onto the pin.

The beauty of this architecture was that each card only needed one set of transmitters to broadcast its data to all the other cards. Since each card had enough receivers to listen to each other’s cards, the equivalent of a multipoint to multipoint architecture was achieved; but without the overhead of additional pins and PCB layers. Not only that, we were able to effectively achieve 1 GB/s line rate using simple inexpensive 2mm connectors. It was the same connector used for compact PCI standard.

Do you have any note-worthy engineering experiences?

In addition to the engineering experiences already mentioned, I also have three patent applications filed with the US patent office. They are for an innovative removable card guide; a unique guidance block; and a method for improving electrical performance of vias for high data rate transmission.

How did the industry change while you were working there?

There have been many changes I have witnessed over the years, but the most profound changes, in my opinion, have been: the commoditization of the personal computer and the internet allowing global collaboration of teams designing products; the transformation from through hole components to surface mount technology facilitating the miniaturization of products; and the evolution of EDA software, virtually eliminating the tedious process of schematic capture and pcb layout, once done by hand.

There has also been a huge paradigm shift in terms of employee/employer relationships. Back in the day it was common for engineers to spend entire careers with the same company. There was a sense of loyalty on both sides that has been lost over the years due to outsourcing of jobs to low cost centers around the world.

What are your favorite hardware tools that you use?

Unfortunately I do not do much hands on debugging and characterizing any more. When I did, my favourite hardware tools were oscilloscopes, VNAs, digital multi-meters, soldering irons and some custom logic probes I designed and built for myself to aid in troubleshooting.

What are your favorite software tools that you use?

Right now I use Microsoft office suite of tools for almost everything. I like Agilent ADS for circuit simulation and channel modeling. I use w-flux 2D field solver and Linpar for PCB geometry impedance calculations. For any photo manipulation and editing, I use Photoshop, and for video editing, I use Adobe Premier Elements.

What is on your bookshelf?

I still have all of my college text books along with many signal integrity books from various authors. But my go-to books have to be: “Signal Integrity Simplified”, by Dr. Eric Bogatin; “High Speed Digital Design and High Speed Signal Propagation”, by Dr. Howard Johnson; and “High Speed Circuit Board Signal Integrity”, by Stephen C. Thierauf.

Can you tell us about the books/papers you have written/co-authored?

I have written and co-authored several papers over the years, particularly in the areas of differential via modeling. The two most notable were for DesignCon 2009 and a recent IEEE paper that was published in May of 2011.

The DesignCon 2009 paper titled, “Practical Analysis of Backplane Vias” I co-authored with Eric Bogatin, Sanjeev Gupta and Mike Resso, won best paper award. It described the methodology of using measurements on a test vehicle to build a high bandwidth, scalable model of long vias, including through and stub effects.

In the IEEE paper titled, “Differential Via Modeling Methodology”, I co-authored with Eric Bogatin and Yazi Cao, we developed a novel method of modeling differential vias based on the geometry, including the effects of the anti-pads. We developed the analytical equations to calculate characteristic impedance and effective dielectric constant. The model correlated well with measured data up to about 13GHz.

In a white paper I wrote titled, “Practical Fiber-Weave Effect Modeling”, I presented a novel, practical approach to establish worst case min/max values for dielectric constant, Dk, and use them to model fiber-weave effect using Agilent EEofEDA circuit modeling software.

Do you have any tricks up your sleeve?

When ever I start a new backplane design, believe it or not, I like to lay down on the couch, put on some Phil Collins on the stereo and start brainstorming by sketching out on a pad of quarter inch graph paper how the cards will be positioned in the shelf and how the links will be routed through the connector fields.

When I’m in the office, I like to use a white board to do some brainstorming to capture my thoughts. I find this useful exercise because I leave it there for a while where I can go back to it from time to time and refine it before I start capturing it in the design.

What has been your favorite project?

There have been many successful projects I worked on over the years at BNR/Nortel, but my three favourites would have to be XACORE non-contact midplane, followed by Passport 15K, followed by T1/T1C repeaters.

What are you currently working on?

I presently have a contract doing system integration and verification for a radio base station application. I also have a blog and write a column for PCBDesign007 online magazine.

Can you sum up Lamsim Enterprises, Inc in one sentence?

Lamsim Enterprises Inc. provides innovative signal integrity and backplane solutions to our clients.

What direction do you see your business heading in the next few years?

To continue to offer my consulting services in high speed signal integrity and backplane design and perhaps branch out into offering design review service for high speed pcb designs.

What challenges do you foresee in our industry?

From a technology point of view, the ever increasing thirst for higher speed interfaces and lower power demands, modeling and simulation will be more important than ever. The challenge here will be for engineers to keep up with the demands placed on them to learn and get up to speed at the same time they are expected to deliver products in shorter and shorter deadlines.