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PCB Design Blog

31 Jul, 2012

Playing Russian Roulette

Posted by Michael Ford

Michael Ford

Luckily, I have a natural aversion to gambling. This doesn’t come from a bad personal experience and I haven’t personally seen the effects that compulsive gambling can have on people. I guess it comes from the feeling of the potential for loss. I buy lottery tickets from time to time and in the name of British culture have been known to put a penny or two on the Grand National horse race. I even won

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19 Jul, 2012

Michael Ford

I read a monthly computer magazine. It is the real thing, paper and everything. Magazines are quite expensive now, in the UK, you can easily spend around £5 (US$ 7.50) on a monthly magazine.  They are full of good stuff. There are columns on various PC related subjects by the experienced, news, reviews, articles, a how-to section and lot and lots of ads. The usual stuff. How much of this though do I

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12 Jul, 2012

Zhen Mu

For SERDES channel designs, board/system designers are told to remove stubs and non-functional pads (NFP) of vias on channels to ensure signal quality at the receiver ends. What confuses them the most is when to consider these effects: does one have to remove all NFPs and stubs in any channel carrying signals with data rates over 1Gbps? Can a design still work even if via stubs are kept? The actual

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SERDES

11 Jul, 2012

Zhen Mu

  Designers dealing with SERDES channels pay more and more attention to signal via effects. Many literatures and guidelines talk about the approaches to correctly configure vias so that via effects on signals can be minimized. Such methods require detailed analysis of single via or differential via pair. With the help of accurate 3D field solvers, vias can be designed to have controlled noise in channels

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3DEM simulation, SERDES

20 Jun, 2012

Enjoy Your Vacation!

Posted by Michael Ford

Michael Ford

Long ago in the mists of time, the young Michael started his career at 7:30 on a dark September morning. It is the UK after all. In I strode, trying to look my best, the tolls of University however showing their effect as the soles of my shoes flapped as I walked, having long since lost containment with the rest of my shoes (some things have not changed then!). I was really happy to have found employment

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13 Jun, 2012

Got integrity?

Posted by Patrick Carrier

Patrick Carrier

Well, of course you do – most engineers are pretty good people.  Actually, as much as I’d like to brag about acing my ethics training course (one of those fun corporate things we do every year), that wasn’t really what I was referring to… Integrity in engineering means that something is as it is supposed to be.  Kind of like structural integrity – there are no holes in

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12 Jun, 2012

Bridging The “Great Divide”….

Posted by Michael Ford

Michael Ford

There was a time, quite long ago now, that I could be put in front of a PC and I would be confident that I could develop software to make the PC do anything that I wanted. I was the geek master of my little universe. It all came about through years of passion for software, starting with the purchase of one of the first kit computers while at University, an impoverished student driven by the desire to

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12 Jun, 2012

Impedance

Posted by Patrick Carrier

Patrick Carrier

Impedance is an important concept in many different realms of engineering. We often see it in our everyday life, especially if you’ve ever hooked up a home entertainment system.  From 8-ohm speaker wire to 75-ohm coaxial cable, the right impedance is crucial to watching things explode on your TV and making sure they sound good too. Simply stated, impedance describes a relationship between voltage

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11 Jun, 2012

What to analyze?

Posted by Patrick Carrier

Patrick Carrier

In my previous blog, I talked about how a printed circuit board is nothing more than a path for signals and power to travel to and from ICs.  For a long time, the path was “short” enough to not even matter.  Then signals became fast enough that the board became a signficant part of the circuit, and the realm of analysis known as “signal intgrity” was born.  Really, signal integrity

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6 Jun, 2012

Don't let your board heat up your ICs

Posted by Patrick Carrier

Patrick Carrier

What?  Isn’t that backwards?  Technically, yes.  The board is merely a pathway through which ICs talk to each other, and receive power to do so.  However, if the power distribution network (PDN) of the board is inadequately designed, it can actually be heating up the ICs. ICs are supposed to be the main source of heat on a PCB.  Heat is conducted from the ICs to the board through their pins. 

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PDN

5 Jun, 2012

Put your charts away

Posted by Patrick Carrier

Patrick Carrier

For over 50 years, designers have been calculating current-carrying capacity on PCBs using charts created by the Navy in 1956 (more specifically NBS (National Bureau of Standards) Report #4283 “Characterization of Metal-insulator Laminates”, D.S. Hoynes, May 1, 1956. Commissioned by Navy Bureau of Ships).  These charts are still in use today; many designers have probably seen them in the IPC-221

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4 Jun, 2012

Co-simulation gets you the real answer

Posted by Patrick Carrier

Patrick Carrier

Simulation is a way of predicting reality.  The more information we put into the simulation, the better our prediction of what is really going to happen.  Certain aspects of electrical simulation, like signal integrity, can be simulated relatively “independently” of other influencing forces.  Sure, there are some temperature dependencies on silicon behavior, and those are typically represented

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DC Drop

28 May, 2012

Michael Ford

If I had invented the laws of physics, things would have been different. In my car, instead of a gas pedal, I would be simply pressing down to be at the speed I wanted to go. No time lag, just get there. No worries about whether the arrangement of my internal organs could keep pace with the infinite acceleration. I, like most others, need however to live in a world where mass counts, power is needed.

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23 May, 2012

Need stitching vias?

Posted by Zhen Mu

Zhen Mu

When trying to design SERDES signals on board, designers often receive recommendations on placing stitching vias around differential signal vias of a channel. The purpose is to provide continuous return current path when signals switch layers, so that the discontinuity of trace impedance can be minimized. Because of the increasing board density, the issues designers are facing by following this recommendation

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SERDES

17 May, 2012

Michael Ford

The evolution of technology has not been great. Not for me. Like many others, I remember watching the first moon landing on television in the 1960s which left me wondering in amazement about what we would be able to achieve in my lifetime. I watched science fiction TV series in the late 1960s, I think one was called “UFO”, which featured futuristic cars, a moon-base from which aliens were shot down.

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