Feb 28, 2014

Guru #2, Bob Dobkin

Of the five men on the original “gurus” advertisement from Linear Technology, Bob Dobkin is the only one still living the dream, doing what he loves for a living. As co-founder and CTO of Linear Technology, his fingerprints are on almost every circuit, every document, and even every advertisement from the company – although he credits Bob Swanson for the idea behind the “gurus” ad. Financially, he could have retired long ago but he says “if I retired from Linear I’d want to go and make circuits.” “Doing analog ICs is like a hobby to a lot of people. It’s a creative outlet. It’s like painting on the canvas but the canvas is silicon.”

Dobkin was born in 1943 and grew up back on the East Coast in Philadelphia. He said he started playing with electronics when he was about six. It was all about making lights blink or buzzers go off. So it goes back well before learning anything in school. He said he thinks “…that many of the people who have good, intuitive feel for analog circuits started well before they got into school as well, building things, doing projects, and then for some of us, it ended up being a profession.”

“Nobody else in my family had any inkling to do any electronics. My parents were business people and my mother was a housewife. My brother, one brother's a doctor. The other brother's in advertising and they don't know which end of a screwdriver to pick up, much less a soldering iron. So I picked it up all on my own.”

From a 2006 interview together with Jim Williams, Dobkin talked about taking things apart. “I was nine. It was 1952. We just got our new nineteen inch black and white TV set which costs as much as a car. And it's in the living room. And I got my screwdriver and I took it apart. And my mom walks into the living room and I didn't just open the back, I had all the chassis out on the floor. I had all the tubes out of it and I'm looking at every different piece. And she just looked in and left... didn't say anything. And I made diagrams when I took it apart. I put it back together again and it worked. And I didn't think anything about it till fifteen years later when I heard her telling the story to some friends – ‘…and I walked into the living room and it was all apart on the floor. What was I going to tell my husband?’”

To which, Jim Williams added, “That's why he's my boss. He put his back together and it worked. Mine never worked again.”

At age 10, he created a contraption that electrified the family's outdoor garbage bins, so that neighborhood dogs couldn't prowl for scraps. At age 14, he made a one-transistor FM transmitter that took over a local diner's background music system, so that he could boom out comments to the cooks and waitresses. "You can always learn more equations as an adult," he said. "We can teach that. But you can't learn to be an inventor if it isn’t in your blood."

In an interview with Electronic Design, he recalled submitting circuits for Ideas for Design. “I remember one I wrote when I was a kid. It was a current source that you could pulse on or off. I don’t know how many letters I got from that,” he said. “It had just two or three transistors in it, but it was really effective in terms of people coming back to me after reading it, which means there were a lot of people out there who couldn’t do that,” he added. “Also, of course, it was useful. There weren’t many couple-transistor circuits that provided a current source you could turn on and off.”

He read hobby magazines, trade magazines or anything with a schematic. Before he went to college he had probably built more circuits than most people have when they finish. Dobkin went to the Massachusetts Institute of Technology (MIT) in the early sixties. He admits that he wasn’t a good student. There were stacks of circuits in the library and he found them more interesting than what they were teaching in class. He left before completing his degree and joined GE Re-entry Systems back in Philadelphia, working in their test instrumentation group. They had a huge calibration lab and it was full of manuals, so Dobkin would go there and read any schematic that looked interesting. In those days every piece of test instrumentation had a full set of schematics. He said he went back to visit 10 years later and many of his systems were still in use. It was a great place to learn, but he wanted to make circuits.

So he left to join Philbrick. He told me he had called Philbrick to ask questions, but the questions were too detailed so they forwarded him directly to Bob Pease. “I was working at GE Re-entry Systems at the time. And Widlar had started at National and was doing the best analog circuits at the time. I had written him some letters and he had asked if I wanted to come out and talk to him. And at the time I had also written some letters to a company up in Boston called Philbrick-Nexus. They made op amps as well. And these op amps were little modules. And they really hadn't gotten into ICs. And I'd written them some letters as well. And I got a job offer to move up there and make some IC op amps, be their chief integrated circuit design engineer. And that's where I met Bob Pease. At the time, I decided I'd probably be better off going to Philbrick. And I started off there. When I got to Philbrick, they were part of Teledyne. There were all kinds of corporate problems between one section and another making the products. I found that you couldn't get anything done and I called up Bob Widlar and I said, ‘You ready for me to come out?’And he said, ‘Come out.’ So I got packed up and I moved west to work for Bob Widlar at National. And that's how I got out west.” "The best part of being part of Teledyne was meeting Carl Nelson who I worked with ever since."

He said that not completing his degree made it difficult for him. He was lucky to run into Bob Pease. Pease didn’t care about your degree; he only cared about what you knew about circuits. And he was lucky to work with Bob Widlar. Widlar didn’t care about your degree, either, just what you knew about circuits.

Widlar was the director of analog circuit design at National, doing all the circuits himself. He had Mineo Yamatake and Ken Craft working for him. Widlar wanted to retire, so he wanted to hire someone to replace himself and that was Dobkin. Dobkin joined National in January of 1970. “Well Bob was one of the few people I considered to be a genius. He was also paranoid, very hard to get along with and drank incessantly. My interview with him was before dinner drinks, two bottles of wine with dinner and after dinner drinks. And I was still standing so I was hired. Of course, I went home and threw up a lot! And he was very egotistical. He didn't think anybody could invent things, at least back in the old days. I think he changed his mind after a while. But he was very good at what he did, made sure that things worked very, very properly. He promoted them properly. I learned a lot in terms of how to be in the analog semiconductor business from Bob.”

“We all did our own app notes. I wrote my own app notes. And he wrote his own app notes. He wrote his own data sheets. He set up the format for them. He gave his own lectures out to the customers. And, at times, he answered the customer phone calls. And that's where we learned about a technique which we call ‘design for minimum phone calls’ because when you make a million ICs; you get half a million phone calls if they don't work right.”

In the words of Thomas Lee, engineers are also congenital speed freaks. Dobkin’s first task at National was to make a faster op amp. According to Lee, “Improvements in process technology help, of course, but often the greatest speed gains are the result of clever topological choices. The LM318, designed by Dobkin, proves this assertion. Built in a process technology not much different from that used to make the LM101A, the LM318 achieved 15MHz unity gain bandwidths and 50V/µs slew rates. Compared against the best op amps of the day, the bandwidth was improved by an order of magnitude and the slew rate by two orders of magnitude.”

He also did the LM319, LM313 and LM395. (Remember, in early National Semiconductor part numbering, LM1xx was a full military temperature range part and the LM3xx was the commercial temperature version.)

The LM317 three-terminal adjustable regulator came about at National in 1976. Dobkin says, "It kind of got started because, at the time, you could make a fixed voltage regulator with three terminals—input, output, and ground," he explains. "But everyone wanted a regulator that they could adjust to whatever they wanted, and there weren't very many good packages with four leads to add an adjustment pin. That's when I came up with the three-terminal adjustable regulator."

I asked Dobkin what his favorite circuit was. His answer was the most recent of his, the LT3080. The LT3080 LDO is a descendant of the classic LM317. Dobkin was directly involved in designing both. "My solution was to substitute a current reference for the voltage reference. That allows use of a very small ballast resistance, on the order of 10 mΩ, which can be achieved simply with a few inches of pcboard trace," Dobkin said. "Using a current source means there is no attenuation of amplifier gain, which helps keep output regulation constant." It was something he wanted to do way back at National, but the technology wasn’t there. It needed low TC resistors and a lot of circuit tricks that he’s learned along the way. “That’ll still be in use years from now,” Dobkin said. “As a building block, it’s not an end in itself all the time. It can be used as many things besides just a power supply. It can be used as a power control. It can be used as a battery charger. You don’t have to put too much around it to change its overall function,” he said.

There are lots of stories about pranks. Dobkin had his fair share. He was the unindicted coconspirator in the infamous Widlar sheep story. The stories about messing with the clocks, making them run slow or fast were all his doing. It wasn’t “the golden age of pranking” so much as some hostility toward National’s management at the time. Of course, these weren’t trivial pranks. These were so well done that the sabotage was imperceptible. Along with the fun, there was a certain amount of professional pride in the pranks. Among peers, the creativity was appreciated – even by the victims.

Rob Walker asked Dobkin what inspired him to break out of National and start Linear Technology? “Too comfortable. National was really getting big. National had the idea that they wanted to be one of the biggest, if not the biggest, IC maker. And the fabs — a lot of pieces that don't necessarily work well when they're homogenized. And contributor type of development. It takes smart people to do it. It takes processes that are tuned for analog circuits and it takes just handling the analog circuits the right way to get out a product that's a good analog circuit. It was getting harder and harder to do that at National. The chains of command were getting longer. The bureaucracy was getting bigger and we ended up talking over the partitions—wouldn't it be nice if we could do this, if we didn't have to use all the profits to fund microprocessors. And finally we went out and did something.”

As Bob Swanson told it, a few guys would come over to his house to drink beer, shoot pool and talk. And finally one of the guys said “look, are we going to drink beer and shoot pool or are we going to start a company?” That was Swanson, Dobkin, Brent Welling and Brian Hollins. In the few weeks between the time they quit National and founded LTC, they added Bob Widlar and George Erdi to the team. Obviously, these were the most talented and experienced analog designers in the business. In the first month they added Carl Nelson and later Tom Redfern. Linear Technology had an aggressive business strategy and, like any start-up, they needed to make money quickly. It would be many years before they would start hiring engineers right out of college. But now they do, pairing them up with experienced engineers to accelerate the learning curve.

“It takes a long time for somebody to become an analog engineer. I kind of think about the process of becoming an analog engineer like learning a language. There's all these pieces of analog circuits that you get familiar with and you know how they work and that's like the words. And when you first see a circuit if you don't have any experience, you can compute what each of the transistors is doing and what each of the currents are doing and finally figure out how it's working. And that's kind of like translating a page by having a dictionary and looking up each word in a dictionary until you finally figure out what that page says. But once you have familiarity with the circuit pieces and how they interact, you get an intuitive feel for where a circuit goes. And it's only until you get that intuitive feel you'll be able to start writing in that language or designing. You can take a big, complicated schematic and you can have an analog designer's experience and he can look at it for minute, two minutes and know what it does because he knows all the pieces and puts it together in his head.”

Along with many new designs and devices, Dobkin has also developed a strong sense of how the design process has evolved, and about creativity. "We have simulation tools, but the tools only let you test the circuits that you come up with on a computer," he says. "They don't actually do a design for you. So the design is only as good as the designer. The tools just make it easier to get that design out."

Modern IC’s are tremendously complex. According to Dobkin, when operating at very high frequencies without the tools, it would be virtually impossible to get them up and running. At some point, however, the engineers need to create something new to solve problems. "They can be more creative," he asserts. "Creativity is the generation of new and useful products. A lot of engineers like their jobs because they're outlets for creativity. Put engineers in an environment where they can be creative, and you end up with a lot of good products."

What strikes me about these “gurus” and most analog people I’ve met is the sense of fun and enjoyment. Even the curmudgeon types have a great sense of humor once they let you get to know them. It’s not just funny pranks, but they really enjoy the process of making circuits. There’s a great sense of pride in building something that customers want to buy and that competitors have a difficult time duplicating. You can see the sparkle in Dobkin’s eyes when he talks about circuits. He still takes things apart. He still studies schematics simply because it’s fun. He enjoys working among the many brilliant engineers he’s hired over the years, sharing circuit tricks. It’s just fun.

“I’ve spent my working life doing what I like,” says Dobkin.


“Bob Dobkin: Creativity Is The Key To Design”, Ron Schneiderman, Electronic Design, Oct. 20, 2002

A review of the book, “The Rare Find”, by George Anders, http://www.huffingtonpost.com/2011/10/20/the-rare-find-george-anders_n_1022311.html 

“IC Op Amps Through the Ages”, Thomas Lee

“The IFD Culture—An Interview With Hall Of Famer Bob Dobkin”, Don Tuite, Electronic Design, Oct. 1, 2008

“Why we're different, by Bob Dobkin”, http://www.electronicsweekly.com/news/components/analogue-and-discretes/why-were-diferent-by-bob-dobkin-2012-10/#sthash.1iLis9bd.dpuf 

“Interview with Bob Dobkin and Jim Williams”, April 19, 2006, Milpitas, CA http://silicongenesis.stanford.edu/transcripts/dobkinwilliams.htm 

“Inventor Updates A Classic 30 Years Later”, Don Tuite, Electronic Design, Aug. 31, 2007 http://electronicdesign.com/boards/inventor-updates-classic-30-years-later

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