Jan 27, 2014

Guru #4, Carl Nelson

Someone asked me once if I was related to Carl Nelson. No, not that I know of. I’ve since done a bit more research into my ancestry and no, I am not related to Carl Nelson.

Carl Nelson is one of the five “gurus” in the early Linear Technology advertisement. The caption under his image says “Creator of the industry standard sample and hold, the first high current regulator, holder of numerous patents and is Linear’s Bipolar Design Engineering Manager.” The sample and hold amplifier is LF398, the high current regulator is LM323 and Carl was granted 10 patents at National Semiconductor, and 32 more after joining Linear Technology. I asked Carl about the name-recognition or “rock star” status that occurred back then compared to now. He said, “We enjoyed a time period where an individual could make multiple big contributions to the technology, because not much had been done yet. Now, a lot of the work goes toward incremental improvements, so the splash factor is smaller. Plus, projects are getting more complex and work is done with teams. There are still plenty of young studs walking the halls at LTC, and they seem to be having as much fun as I did, so some things are the same.”

So what were Carl’s footsteps on the way to Linear Technology?

Departing from the theme of “Analog Footsteps”, Carl did not got to MIT or Stanford and didn’t work for Fairchild. Carl grew up in Homer, Alaska – before it was a state. It was a tiny little town and Carl was class president of his high school (in a class of 17 kids). But don’t put Carl into any stereotype. Around 1959, Carl Nelson and Jimmy Vollintine hatched a plot to scare the bejesus out of the younger grade school kids waiting in the hallway to get their vaccinations. Jimmy screamed in the outer part of the office after getting his shot, and Carl pretended to drag the unconscious body out of the office and down the hall past all the little kids. There was pandemonium. Twenty five years later Carl met the nurse in charge at Millie Nelson’s house in Palm Springs, CA. It turned out that the nurse never knew what had caused the kids to panic, and she was still mad...

I asked Carl about the inspiration for his career in analog design.

“My standard cracker-barrel story is that I made an oscilloscope out of a Mason jar in high school. That’s totally untrue, but I did fiddle around with ham radios a little, actually designed a tube amplifier stage, and built a snazzy little AM radio from a kit. I learned a valuable lesson from the kit – one mistake and electrons is just junk. The radio wouldn't work, even after I spent hours and hours going over the instructions trying to find a mistake. My dad worked as a flight controller, so he took the kit to the airfield electronics maintenance guy, who eventually found the problem. There were two 5-pin terminal strips – the kind you wrap wire around to make solder connections. One had the 2nd pin from the left as a ground pin, and the other had the 3rd pin as ground. I had reversed them. I still have the radio and keep promising myself I will restore it.”

“As a little kid, I used to try to sneak into the electronics room at the airport when dad was on duty. It was crammed with all kinds of large glowing, humming, clicking electronics with lots of knobs, dials, and meters. It was always hot in there – a welcome change from the Alaska outdoors. But it was also probably pretty dangerous, so I rarely succeeded in staying long.”

Being from a small town, Carl preferred to go to a small college. He settled on Northrop Institute of Technology in southern California. NIT doesn’t have the name recognition of MIT or Stanford, or quite the rich history. NIT was founded by Jack Northrop of Northrop Aviation, originally as the Northrop Aeronautical Institute in 1946, to train aeronautical engineers and mechanics to work at Northrop. That reminds me of my own alma mater, General Motors Institute (now Kettering University). It was renamed NIT in 1953 when it became independent from the aviation company. It closed in 1993 for financial reasons, although a portion was sold to Rice Aviation. Rice then created what is now the Northrop Rice Advanced Institute of Technology which continues to operate in the old Northrop Institute of Technology facilities.

Carl graduated as an electrical engineer in 1967. But even there, he spoke his mind.

“I was nearly kicked out of NIT after I wrote a very inflammatory lab report. We were studying clipping and clamping circuits using diodes, capacitors, and resistors. They gave us function generators along with diagrams about how to hook them up, and waveforms to expect. Problem was, most of the circuits failed to operate as expected. The other kids wrote these long explanations trying to justify the bogus results, but I knew something had to be very wrong behind the scenes. So I played around until it suddenly became apparent that the function generators had cap-coupled outputs. That made them useless for studying clipping and clamping circuits. The big problem was that the lab instructors had created the lab material, complete with 'scope photos, from something that didn't work. So they must have falsified the data at some point, making it look like it was supposed to. I did something to get a DC coupled output, got the right results and wrote the report. But then I added a long diatribe about ethics, morals, and whatever other crap a 19 year old can dream up.  The professor called me into his office and told me my heart was in the right place, but I needed to fix my mouth…”

His first job was at Continental Device Corporation in research with the promise that he might be able to join their tiny linear IC design group. Continental was a spin-off from the semiconductor division of Hughes Aircraft. Most of us forget that the semiconductor industry was more than just Bell Labs, then Shockley, then Fairchild, then boom! Of course there were transistor companies that failed to make the transition to integrated circuits. But there were also some other significant companies with significant spin-offs. Texas Instruments and Motorola are two who survived and never had any spin-off companies eclipse them. But Hughes Aircraft had a few spin-off companies that did fairly well before blending with the other Fairchildren. Pacific Semiconductor led to TRW. Ed Baldwin, the first general manager at Fairchild, was actually from Hughes and he left to join Rheem Semiconductor with other Hughes defectors. A quote from Hughes in 1956 foretold the future, “Within four years the semiconductor industry will increase fivefold, resulting in extensive expansion of silicon and germanium production, according to Hughes Product Group of Hughes Aircraft.” Joseph S. O'Flaherty was the manager of the semiconductor group at Hughes and he left to start Continental Device Corporation in 1960.

I found a notice in a Cal Poly newsletter from 1968 that is likely quite similar to the one Carl responded to:

Pete Johnson, industrial relations manager, will interview seniors in EE, EL, IE and ME and Physics and Chem for positions as engineering management trainees and research engineers.
Continental Device Corp. is one of the leading silicon semi-conductor manufacturers, with plants at Hawthorne, California; Mooresville, North Carolina; and Hong Kong, with a complete line of silicon planar semi-conductors that range from high conductance switching diodes and UHF tuner transistors to high power devices.

Carl shared an early experience from Continental. “One of my first projects was to design and build a 30,000V aluminum vapor deposition machine. Looking back, I'm lucky to have survived… I was walking down the hall one day with a Dewar flask of liquid nitrogen for the deposition machine, and as the head lab technician passed me, he said, "What's in there?", followed by plunging his hand into the flask. He jerked his hand out just as fast as it went in, commented "have to do that fast", and walked on down the hall. Scared the crap out of me, but I guess that was the point.”

“Continental had designed a 15V monolithic three terminal regulator. I took one look at that and my fate was sealed. I made suggestions for improving it, and promptly got transferred to the fledgling linear IC group. I became aware of the goings-on of Widlar and Dobkin at National, and read everything they published. Continental was bought out by Teledyne, who had also bought Amelco, and I was transferred to Mountain View to work at Amelco.”

Continental would help fund the founding of Semtech and O'Flaherty remained on the board of directors for many years.

Amelco is an interesting side story. Amelco is a spin-off from Fairchild, founded by four of the eight original Fairchild founders: Hoerni, Last, Roberts and Kleiner in 1961. Jean Hoerni, of course, invented the planar process which totally changed the industry. Financial backing was arranged by Arthur Rock with Teledyne Corporation. Hoerni would then go on and found Union Carbide in 1964 and then Intersil in 1967.

Ted Malcolm recalled this story about working in Mountain View:

“Working at Continental Device, a semiconductor spin off from Hughes Semi, in 1961 thru 1965. When VP Jim Hines called a mgt. meeting and announced that we were no longer to gather at a local watering hole for lunch or after work. The reason given was because of what he had learned, about Fairchild, during a recent visit up north to the Wagon Wheel restaurant. At that time Fairchild was the enemy up north and the "wheel" was their local watering hole. We were using the alloy process with 1 1/8 wafers which did not yield many DO7 size die. The planar process began to be used after obtaining a license from Fairchild.”

“Being interviewed by plant mgr. Fred Bialeck in 1965 and being shown what he referred to as the most important piece of paper in his office. On it were the names of his key people and the areas of the factory where they had experience. No wonder they called it ‘the academy’.”

For Carl, National Semiconductor was the center of the analog world.

“I second sourced some of the National stuff and worked on proprietary designs, but secretly dreamed of working at National. Then one day I got a phone call out of the blue from Dobkin, who had somehow heard of me, and wanted to meet over lunch. I can still see and smell the huge mushroom salad I was eating when he asked me if was interested in working at National. Amelco sent the president in to talk me out of leaving, but he was the third president in 18 months, and the Amelco ship was sinking, so I waved goodbye and never looked back.”

“I remember Dobkin showing me to my office, pointing at the phone, and telling me I would be fielding most of the customer calls on National linear ICs. Not long after, the Army called, wanting to know if National would design a timer for the Grasshopper anti-personal mine such that the bomb would explode horizontally right at waist height after it jumped out of the ground. I told them to take their bomb and shove it. When I told Dobby what transpired, he stared at me for a second, then said ‘OK’.”

“We designed whatever the hell we wanted, and got it right most of the time. I got to correct Dobkin and Widlar from time to time, so we fed off each other to make stuff happen, but in my mind those two remained firmly on an imaginary pedestal.”

In 1981, Dobkin, Widlar, Swanson, Hollins and Welling left National to start Linear Technology. The split was not amicable and lawsuits were plentiful. Carl was still at National.

“I actually got Dobby's job when he left National. He told me that legally he couldn't recruit me, and I told him I wanted to try his job as director of ALIC. But National was going through major changes at that time, throwing huge amounts of money into emerging digital markets. They made quite a few decisions that made life in the linear groups much less fun. The final straw for me was a layoff caused as much by management error as the economy.”

Carl was not one for obfuscation, always managed to speak directly in his data sheets. From the LM323 data sheet: “New circuit design and processing techniques are used to provide the high output current without sacrificing the regulation characteristics of lower current devices. … The 3 amp regulator is virtually blowout proof.”

And from his seminal switching regulator application note, AN19:

“WARNING Before reading this section, be aware that the intent of the author is not to insult, but rather to relate in an attention-getting manner a list of goofs that, in many cases, he personally has had to own up to.”

1. Transformer Wired Backwards Those dots indicate polarity, not smashed flies.

5. Fred’s Inductors (Or Transformers) Inductors are not like lawn mowers. If you want to borrow the one out of Fred’s drawer, make sure it’s the right value for your application.

9. 60Hz Diodes The LT1070 will eat 1N914 and 1N4001 diodes, and not even burp.

12. Didn’t Read the Datasheet Then you shall have no pie.

I asked Carl about the LT1070 development and AN19.

“The 1070 was the result of going back to basics. I spent many days playing with all the possible ways inductors, diodes, and capacitors could be connected to create a switching power supply. I was mostly reinventing the wheel, but it gave me a good grasp of the principals involved and a great appreciation of the symmetry inherent in topologies. I was pretty sure customers wanted the simplest possible design so they could understand it and get it up and running quickly. It didn't take long to realize that five pins was the minimum needed, and that matched up with the 5-pin TO-3 and TO-220 packages, so it was a no-brainer. Then lots of work went into making the design work over as wide a range of input and output conditions as possible. Next was adding extra functions to as many pins as possible so users could play if they wanted to.”

“AN19 was born because I suspected (and marketing confirmed) that many companies needed to use in-house design engineers who had little or no switching power supply design experience. If I could write down everything I had learned, I assumed it would encourage more companies to try their hand at in-house designs as opposed to modules, etc. The project quickly started raising more questions than it answered, and I knew it would consume me at work. So I shifted most of the effort to home, staying up until the wee hours of the morning night after night for months. There was no practical way to verify equations as they were developed, so I spent a lot of time doing cross checks and sanity checks. I began to realize how difficult the design process was going to be for designers tossed into the fray, so I tried to maintain a sense of humor from time to time - hence the 'you shall get no pie' quote.”

Carl said his career choices were based on fun and glory, not necessarily in that order. He certainly had fun. Look up any of the posts about office pranks with the likes of Jim Williams and Bob Dobkin, and you will find Carl well represented. Based on his circuits, he clearly earned his “guru” status. But don’t stereotype him as a power guy, either.

“My best patent was on the LM35 at National - the centigrade temp sensor. I was mulling about bandgap theory one day and because I love the power of symmetry, it occurred to me that the magic of adding Vbe and delta Vbe to get a zero TC reference, and having zero TC always come out to 1.25V, might have a symmetrical equivalent. In other words, if you subtract them to get a strong linear drift and you do it in just the right way, the result might be a theoretically accurate temperature sensor. It turned out to be true – trimming the delta Vbe portion correctly makes both the slope error of the sensor and the offset error go to zero at the same time. So you can trim the chips once at 25C at wafer sort and get a very accurate centigrade temperature sensor.”

Carl retired from Linear Technology and moved back to Alaska. He’s still doing some circuit design, but we can’t talk about it yet.


SEC News Digest, Issue No. 67-79, April 26. 1967 http://www.sec.gov/news/digest/1967/dig042667.pdf

SEMI Oral History Interview: Monte M. Toole, Interviewed by Craig Addison, SEMI

I remember when, Ted Malcolm, Oct. 4, 2007 http://corphist.computerhistory.org/corphist/view.php?s=stories&id=347&PHPSESSID=c3f5124ac78ffafa90924b8343726678 

Semiconductor Boom's Just Starting
Hughes sees fivefold increase in silicon and germanium by 1960; announces new diode and rectifier
Chem. Eng. News, 1956, 34 (50), pp 6042–6048
Publication Date: December 10, 1956

Thursday February 8, 1968 Cal Poly

High school yearbook, [http://homerhighak.com/Homer_High/Welcome.html ]

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