Breakdown

Breakdown

This week’s theme at Engineer Blogs asks the authors to recount their path to “success”. What were the turning points? Who was involved? And so forth. The arc of a storyline usually tells of a protagonist that is transformed as the events unfold from beginning to end. Tiger Woods is a good example — rising prodigy, international superstar, fall from grace. Adolf Hitler is another great example — struggling artist, dictator extraordinaire, suicide. Or we can look at Barack Obama — fatherless childhood, President of the United States, Kenyan Muslim Marxist.

But not everyone is blessed enough to have a sweeping story arc in their lives. Donald Trump, for example, is more of a sine wave than an arc. And for me, it’s more or less a straight line with a shallow slope. A suburban upbringing. Good at math and physics in high school. Studied engineering. Works in engineering. Continues to live in the suburbs. A bland, meh, blah, middle middle-class kind of life where the dots line up predictably.

But my virtual life as Fluxor is quite different. I feel like a transistor with just a bit too much voltage on the gate terminal. The transistor has lots of gain, passing lots of current, and is using lots of power. Lots of fun at the beginning, but that slight over-voltage will create headaches over time. One of those headaches is called time dependent dielectric breakdown, or TDDB.

As an analog chip designer, TDDB is one of those checks we need to do on our circuits but no one ever really wants to do it. It’s boring. It’s tedious. This check is to ensure the circuit has good reliability in the field, but it has nothing to do with functionality of the circuit itself, which is where all the fun is when you’re a designer.

So what is TDDB? As the name suggest, it’s a failure mechanism whereby an over-voltage applied to the gate terminal of a MOS transistor will, over time (hence time dependent), cause the dielectric layer of the gate terminal to break down, shorting the gate terminal with the other two transistor terminals — source and drain. For those not familiar with the operation of a MOS transistor, it has three terminals (gate, source, drain). You can think of the gate as a valve that is controlling the flow of water between pipes on either side of the valve (source and drain). Applying voltage to the gate is similar to pushing on the valve to allow water to flow. Or in the case of the transistor, to allow electrical current to flow. But don’t push on that valve too hard, or you may end up cracking the valve allowing water to spray out everywhere. Similarly, too high of a voltage on the gate terminal for too long will cause electrical current to seep out onto the gate terminal where it wasn’t intended to go.

MOS transistor cross section
Cross-section of a MOS transistor. Note the thin layer of gate dielectric.

While my real life story is but a straight, predictable line, my virtual persona does indeed have an arc. I, as Fluxor, was born in January of 2009 along with the Flying Flux blog. Readership at the Flux started out slow and nudged up over time. Then in January 2011, I joined forces with three others to start Engineer Blogs. Lots of merriment; lots of excitement; a lot more readers. But life finally caught up with me. Too much over-voltage for too long, I guess. The transistor finally broke down.

So here I am, as Fluxor, penning my last ever blog entry. And it’s fitting that my last post is on Engineer Blogs. Earlier today, I posted a much more personal post over at the Flying Flux on why I’m leaving the virtual world behind. So take a gander if you’re interested.

As I fade into the background, I’ll nevertheless stay on at Engineer Blogs as the ceremonially titled “editor-at-large”, working behind the scenes to make sure no typos slip through and no participles are left dangling (actually, it’s perfectly grammatical to dangle participles). I’d like to say a big thank you to everyone at Engineer Blogs, from the support of Chris, Cherish, and FrauTech, to the writings of Paul, Miss Outlier, and GEARS, and to all of our readers. It’s been fun.

The only place where I can find an quality pirated copy of this video clip is on a Chinese website. Go figure.

4 comments

Best of luck Fluxor, you will be missed. Your posts were always interesting and fun to read.

The only reassuring thing for me is that you’ll still be around as an editor. I’ll miss your writing too, it always made me say, “Wha?…Wait, wha?? Can he say that?? Oh yeah, he can…now I’m glad he did.”

You wrote some of my favorite EBlogs posts and are clearly a great writer so will be missed, but it sounds like you are making a good choice. Good luck and enjoy the time with your family.

Goodbye Fluxor. I really enjoyed your posts and your last one was exactly the sort I like. Electromagnetism and circuits in a way I never had to think about in my career. I always enjoy learning something new.

Nice choice of Elton John, I’m sure should you change your mind, in a few years, after you’ve spent time beyond the yellow brick road, there will be a place for you in cyberspace again, and this grizzled Engineer in his advanced youth will be pleased to read your prose.

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