Tag Archives: Jim Williams

Useful App Notes: Part 2

AN104 – Load Transient Response Testing for Voltage Regulators, Linear Tech

An app note written by the late great Jim Williams back in 2006 discussing how to test linear regulators by applying a load transient to the output. These techniques discussed are also directly applicable to switching regulators as well making the app note doubly useful. My favorite parts of this app note are Figures 6 and 8 which show two interesting transient generator circuits, one BJT based and the other FET based. At the moment I’m trying to gather up the necessary parts to prototype one of the circuits and possibly throw it in a project box to use at work. A great resource for anyone doing work in power electronics.

ANA – The Monolithic Operational Amplifier: A Tutorial Study, National Semi

Want a fantastic reference about the intricacies of op amp design? Look no further than this app note written by Bob Widlar. Covering everything from input/output stages, to techniques for increasing slew rate and proper layout, any and all relevant topics related to op amp design are discussed.  There’s even a section on thermal feedback which is interesting as it’s not a topic typically covered all to often. While I don’t think I would recommend this app note as a stand alone reference for a beginner, it’s perfect for someone looking to expand their knowledge on op amp design. If you are a beginner I would suggest pairing ANA with either Johns & Martin or Gray & Meyer. Fun Fact: Gray and Meyer are cited several times in the bibliography.

The Data Conversion Handbook – Analog Devices

Not exactly an app note but still another good reference to keep at hand. If you’re looking for a general overview of ADCs and DACs  along with a bunch of other useful information I highly recommend this book. Chapter 1 is an interesting history of converter technologies throughout the ages. Chapter 2 discusses sampling theory and defines converter specs. Chapter 3 covers the various topologies of DACs and ADCs from a primarily applications standpoint rather than a design one but is still incredibly detailed.  Chapters 6 and 7 cover interfacing and all the various support circuitry that goes into properly using converters in your design. Chapter 9 has a some good information regarding board layout, passive components, prototyping, and more. I read through most of this handbook two summers ago during an internship while waiting for automated tests to run and I can say I learned quite a bit.

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A Call to Arms

I’m sure it’s not news anymore to most of the readers here but recently there has been not one, but two devastating blows to the analog electronics industry.  Legendary Linear Tech Applications Engineer Jim Williams passed away on June 10, 2011 and National Semiconductor’s Analog Wizard Bob Pease (the self crowned Czar of Bandgaps) also passed away on June 18, 2011.   EDN author and fellow analog engineer Paul Rako fondly remembers both analog giants in two heartfelt posts on EDN’s website here and here. You can also find a tribute to Williams on Linear Tech’s website (found here) which also links to a collection of his app note guaranteed to provide you with enough reading material for the foreseeable future. [Update] National Semi has also added a tribute to Bob Pease on their website found here.  There’s an excellent video to go along with it that’s well worth the time to watch it (if anyone from Maxim is reading I apologize but your product catalog as Pease’s floor mat was pretty funny).

No one can deny that their unexpected passing is a blow to EE’s everywhere and both men will be greatly missed.  It is unlikely that either Williams or Pease will ever be replaced. In his article on Pease, Rako mentions that there are still many great analog designers in the industry today and while I agree with him, I do claim that we as an industry are currently left with a void to fill in terms of engineers who are as vocal as both Pease and Williams were.  There is now a need for engineers and makers who possess the same passion as these two great men to step up and inspire and teach others with their writing.

My challenge to not only analog fans but all engineers, coders, makers, hackers, etc. is to carry on where Jim Williams and Bob Pease left off.  Be passionate about your work, take pride in it.  Look to teach. Look to inspire. Let your enthusiasm show through in every project. Let people know what we do as engineers may not be easy but the challenge it provides is both exhilarating and at times, fun.  These are the ideals that should be present each and every day you sit down at your bench. You don’t have to be a circuit junky to see  these principles shine through in Williams’ and Pease’s work, they’re pretty self-evident.

So grab your ‘scopes, grab your dev boards, your MakerBots, and your soldering irons (not by the hot end). Take them and make something.  If you’re not a maker, write an article on a bit of theory you’re knowledgeable on or just any topic that interests you.  Throw the results online for others to see be it in your own blog, an Instructable, up on Hack a Day, YouTube, whatever.  Carry on the legacies of passion, knowledge, and dedication left behind by Jim Williams and Bob Pease.  While they can’t be replaced, their memories can be honored through the work of those they inspired.

Sadly, I never had the opportunity to meet nor work with either Pease or Williams. However, the two have inspired me immensely through their countless publications.  Ever since I first stumbled across The Best of Bob Pease on National’s website and Analog Circuit Design: Art, Science and Personalities  a few years ago I’ve been hooked on reading everything these two have put into print.  Both of them have taught me a great deal on not only analog circuits, but also the passion required for really loving the work that you do.  As I prepare to go off into the real world after summer ends and start my own career as an apps engineer, I hope that perhaps one day a few of my own app notes can be as well regarded as those written by Williams and Pease and can inspire budding EE’s the way they have inspired me.

To Jim Williams and Bob Pease, may they rest in peace…