An innovator in power-supply design who anticipated the trend toward higher frequency switching,
an illuminator of power-supply topologies, and one who introduced many engineers to the promise and perils of power MOSFETs, Rudy Severns has made diverse contributions to the power electronics field in a career spanning five decades as an engineer, author, instructor
On the 50th anniversary of his first jump from a biplane, Rudy Severns went skydiving yet again, pushing his lifetime total to somewhere in the vicinity of 500 jumps. Throughout his career, he took breaks for months-long sailing voyages, which usually necessitated a job change on his return. When it was time to fulfill his military obligation, a young Severns parlayed his experience as a radio operator into a stint with the Army's Special Forces, where he learned the skills of unconventional warfare.
Given his bent for adventure, is it any wonder that Severns' career as an engineer, author, instructor and consultant was marked by a similar sense of adventure? When the early generations of power MOSFETs were helping to propel switch-mode power-supply (SMPS) design into the commercial mainstream, Severns realized that engineers were limiting their power-supply designs to a very narrow set of topologies. In writing the landmark text Modern DC to DC Switchmode Power Converter Circuits, which he co-authored with Ed Bloom, Severns set out to introduce engineers to the hundreds of power-supply topologies that were available.
A similarly adventurous spirit may have been at work in the late 1970s when Severns made the then-radical proposal to a PowerCon audience that power-supply designers consider moving to higher switching frequencies for certain applications. His PowerCon 5 paper anticipated what would become an industry trend toward high-frequency switching only a few years later. But that trend was anything but obvious at the time, and the show organizer even suggested for his next paper that he go with something less “blue sky.”
Severns was also sailing into uncharted waters when, as a semiconductor applications engineer in the late '70s and early '80s, he began working with power MOSFETs. Severns not only needed to figure out how to use these new components, he had to teach power-supply designers how to use them. That gave Severns his first foray into teaching power electronics, an activity with which he would become more involved in time.
Working with those early power MOSFETs, Severns was also among those who were discovering their peculiarities and their failure modes. He wrote several papers documenting these problems, worked with customers to address these issues in their designs and then worked with his company's device designers to eliminate some of the early MOSFET weaknesses.
Prior to becoming an applications engineer, Severns worked in industry for many years designing high-voltage, high-power supplies for space, military and science applications. In these assignments, the unforgiving nature of high-voltage design undoubtedly added an element of danger and adventure to his work, while also giving Severns a grounding in SMPS technology and opportunities to innovate.
But before that career started, there would be several adventures that would help shape his later life in ways big and small. As a youngster, Severns would get a taste for electronics and experimentation, beginning his lifelong involvement with amateur radio. He would receive a surprisingly good grounding in math and science at his small country high school.
Then after graduation, he would get a chance to mature in the military while undergoing some rather exotic training in an Army Special Forces unit. And finally, he would enroll in a college engineering program, where he would tailor his curriculum to suit his interests, while gaining valuable work experience as a technician in particle accelerator labs.
Small School, Quality Education
Born in San Francisco in 1937, Severns’ family moved a number of times before settling just outside of Bremerton, Wash., around the time Severns entered the sixth grade. Severns’ mother was a licensed vocational nurse and his stepfather was a pipefitter at the naval base in Bremerton. Though their educational backgrounds were modest, his parents conveyed a deep respect for education. That attitude no doubt helped Severns to take advantage of the opportunities he found at Central Kitsap High School. There, says Severns, he received an “extraordinarily good education.”
Though it was a small, rural high school with only 92 students in his graduating class, Central Kitsap had very good teachers. As a result, the school offered a particularly strong math, physics and chemistry program.
For any high school to be so strong in math and science was a rarity in the 1950s, says Severns. (“Senior math class included calculus,” recalls Severns.) So, it was all the more remarkable that Central Kitsap was a “country” high school. Just a few years ago when Severns attended his 50th reunion, he and his classmates were amazed to discover that 20-plus members of their class went on to become engineers.
First Steps in Electronics
Like many who eventually took up electrical engineering, Severns had an early interest in electronics that was sparked by an interest in radio, particularly short-wave radio Around the age of 12 or 13, Severns began experimenting, building crystal sets and one-tube receivers. These early activities even gave him his first experience with power electronics.
At one point, Severns had obtained a war-surplus aircraft receiver for $5, but it required aircraft power to operate. So, he built his first power supply, consisting of a line-frequency transformer and tube rectifiers, which would provide the filament and plate power required by his receiver. Reflecting on that unregulated power supply, which he built in the ‘50s, Severns notes, “It was very much the technology of the day.”
From short-wave radio listening and experimenting, Severns made the natural transition to amateur radio after one of his high-school teachers introduced him to a local ham. That radio amateur helped him learn Morse code (continuous wave or CW, in ham parlance) and study for a ham license. After passing the tests, Severns got his first ham license at the age of 16 and became active as an amateur radio operator.
At 17, that experience opened the door for him to become a radio operator in the naval reserves, which he was encouraged to join by a neighbor who was an officer in the reserves. His status as a ham gave Severns advanced standing in the naval reserves because the technology used by amateur radio operators was close to the technology of the day in terms of how the Navy communicated.
After graduation, Severns spent a summer living with his grandfather in Berkeley, Calif., and attending a University of California, Berkeley summer session. Although he did well academically, Severns decided he was not emotionally ready for college and, knowing that he would have an obligation for military service, decided to enlist.
Although his initial intent was to join the Navy, he soon discovered that the Navy, which was ramping down in the wake of the Korean War, did not need radio operators. However, the Army did, particularly in the Special Forces units. So, Severns soon found himself shipping off to Fort Bragg, N.C., where he would train with the 77th Special Forces Group. After about 15 months there, he was reassigned to the 10th Special Forces Group in Bad Tolz, Germany.
Though his radio skills were his ticket into the Special Forces, where he was surrounded mostly by much more seasoned soldiers, radio communications were not his only responsibility. The main objective of the group was to master the skills of guerilla warfare, so in times of war, they could go behind enemy lines and organize local partisan groups to fight.
Consequently, as a member of a Special Forces unit, Severns trained in the use of all types of weapons and learned demolitions. That training wouldn’t translate into anything he could use later as an engineer. Nevertheless, the danger of the work would require special care, a theme that would be echoed in his later work in high-voltage electronics.
A Quick Start in Engineering
After his three year stint in the Army was over, Severns was ready to start college. However, he would quickly find himself with other responsibilities, as well. In the fall of 1960, Severns began working, enrolled in college, got married and started a family. As if that wasn’t enough, the requirements for becoming an engineer had changed, having gotten stricter in the four years since he graduated high school.
To get into an engineering program, Severns had to prove himself by getting high grades in required courses. He did so during his first year of college at San Francisco State, during which time he was also working as a technician at UC Berkeley’s cyclotron particle accelerator. While working at Berkeley, he learned about the engineering program at UCLA and how it was closely tied in with the aerospace industry in Southern California.
So, wanting a practical, industry-oriented education, Severns enrolled in UCLA’s engineering program. Although UCLA allowed students to specialize in a particular area, it offered a general engineering program rather than an electrical engineering (EE) program. As a result, Severns found himself studying a diverse range of non-EE subjects such as soil mechanics and how to build dams.
However, Severns didn’t simply follow a prescribed curriculum, he “worked the system” to tailor his studies to his interests. “Because I was much older than the majority of students in my grade level and had a lot of practical experience, the dean allowed me to skip many of the required lab courses and in their place take many extra electrical engineering classes and math classes. I graduated with 156 semester hours.”
Much of that additional coursework was in electromagnetic, including a class in magnetic amplifiers (mag amps). “By that time, I was really interested in RF and power,” says Severns. The engineering studies came naturally to Severns. “For me, the real trouble was having to work and raise a family. The engineering was just fun. To this day, I do it for fun.”
Throughout his time in college, Severns worked to pay his way and support his family. That included taking a year off in 1962 to work for Philco Ford, which sent him to Indonesia to install and operate a tropospheric forward scatter system — a precursor to satellite-based systems. This system would provide high-bandwidth radio communications for the Indonesian army across the country’s chain of 1000 islands.
After that experience, Severns returned to school and to his jobs as a technician (and later, junior engineer) at various particle accelerator labs such as UCLA’s cyclotron and CalTech’s synchrotron. In these jobs, he designed and built RF amplifiers, pulse modulators and power supplies. These were mostly tube-based designs because of the voltages and power levels involved. For example, a power supply operating off-line might be needed to generate 50 kV at 10 A using a transformer and multiphase tube rectifier.
The work was dangerous and much of the design challenge related to maintaining safety. “When you’re working at high power levels and you make a mistake, things blow up. Lots of smoke and flames to inform you of your mistakes,” says Severns.
But around this time, the early ‘60s, there was the shift in technology to solid-state that affected even the high-voltage area. For example, in the particle accelerator applications on which Severns worked, devices like mercury-vapor rectifier tubes were being replaced by silicon “door-knob” rectifiers from the likes of Unitrode. These rectifiers were stacked to achieve the necessary voltage ratings.
As mentioned previously, a desire to work on new and interesting things drove Severns to make many of changes in employment. However, intellectual curiosity was not his only inspiration.
“In 1974 when I left Hughes, I did not leave Hughes for another job. I left Hughes to jump on my schooner and go sailing for the better part of the year in Mexico. I just quit,” says Severns who notes he was divorced at the time.
A sailor’s wanderlust would tempt him away from other jobs too. “In 1977, I left Magnavox, bought a brand new boat, picked it up in Lake Ontario on the east coast up in Canada, sailed out to the east coast, Newfoundland, and did everything down as far as Chesapeake Bay, says Severns in describing his next adventure, which lasted six or seven months.
Then in 1980, Severns left Intersil for six months and took his new wife sailing “up the west coast of the US to British Columbia and spent the summer there and sailed back home again.” That trip more-or-less marked the end of his career as an engineer working within a company. On his return, Severns began doing consulting work for International Rectifier. And with the exception of a stint at Siliconix, he continued to earn a living as an independent consultant for the next 25 years.
Becoming a consultant held many attractions for Severns. Working as an engineer in the corporate world, he never had an interest in becoming a manager, wanting only to do engineering work. However, that aversion to managing severely limited his opportunities for advancement. Consulting, on the other hand, allowed Severns to work on a variety of interesting engineering problems, avoid management responsibilities, while getting paid well.
And because consultants are paid well, there was the added benefit that the customer usually listens to the consultant’s advice, even in cases where they would not accept the same advice from their own engineers. The downside of consulting, says Severns, is it offers “no security of any nature.”
However, that factor did not bother Severns, who never lacked for work anyway. Why was there so much work for Severns as a consultant?
“It was actually multiple things,” says Severns. “First of all, it had a lot to do with the MOSFET coming in and other component changes so that much higher frequency design was going on. Then there was the fact that switchers were now acceptable, they became the standard and the applications for switchers greatly expanded. So there was an enormous increase in work just in the field of switchers. And as soon as the applications expanded, they were short of bodies, especially experienced bodies.”
Much of Severns engineering work involved innovation. But Severns observes, being a consultant often requires that one shy away from innovation when advising clients. That’s because the goal is to help the customer solve the problem without taking any undue technical risks. “So very often I had to give very conservative advice,” says Severns.
As an example Severns cites his work on General Motors’ electric vehicle (EV-1) project. “For the EV-1, I suggested a new design for the charge port, but when it came to all the charge electronics, I said, ‘do it simple, do it this way because it’s reliable. Don’t be elegant, don’t invent.”
Of course, another big attraction of consulting was that it allowed Severns to “abandon the real world” from time to time and go off on his lengthy sailing trips. Curiously, it would be on one of his longer ocean-going adventures when he would do some of his most creative and influental work.
In 1982, Severns took off on a sailing adventure that would take him to Mexico, Hawaii and back over the course of an 18-month trip. During this trip, he wrote a draft of a textbook that would broaden the perspectives of many power supply designers by introducing them to the wide array of power supply topologies that existed.
Severns' work during his college years with high voltage, high power and RF provided him with good experience for the engineering jobs he would take after graduating from UCLA in 1966. Severns recalls that the job situation at the time for graduating engineers was “wonderful,” as a result of the booming aerospace and military industries and the heavy funding of big science.
Upon graduation, he picked up where he left off in his engineering work by taking a position at the Los Alamos Scientific laboratory, where once again he designed high-power RF amplifiers, pulse modulators and high-voltage, high-power power supplies for the lab's linear particle accelerator. That job also gave Severns the opportunity to publish what would be the first of many papers on power and RF topics.
In that first paper, Severns described techniques for transmitting a pulse across a high-voltage interface to RF pulse modulators that were floating at 50 kV to 100 kV. One of the innovative techniques used light signals transmitted over light pipes using some of the early Hewlett-Packard optoelectronic components.
Severns continued designing pulse modulators and power supplies when he moved to Continental Electronics Corp. in 1968. Another two years later he moved on again to take a job as design engineer at Analog Technology Corp., where he designed power converters for spacecraft physics experiments. Then in 1971, he took a job at Hughes Aircraft Corp. This was followed by stints at Magnavox Research Laboratory from 1974 to 1978 and a short stint in 1978 at TRW, space systems division.
Then as now, job hopping was fairly common among engineers. “In the early '70s, in Southern California, jumping from one company to the next was de rigeur,” says Severns, and he did so for various reasons. “But in general, my motivation was to find something interesting to do. I looked at the work that was available and what I was doing today. If I was finishing up a project, and it was getting boring and routine, I'd go off and find a new job.”
Fortunately for Severns, there were many interesting jobs in the late '60s and early '70s. At Analog Technology, he worked on deep-space instrumentation for projects such as the Mariner mission to Mars. Then at Hughes, he did design work (using traveling wave tube amplifiers) on some of the early communications satellites. Both jobs were “really fascinating work” that involved developing new circuits.
At Magnavox, he was among those doing the early development work on global positioning systems (GPS). For Severns, the GPS project was his first opportunity to design low-voltage dc power supplies, which would power the GPS receivers.
Chances to Innovate
Nearly all of these power supplies for the spacecraft and GPS systems were SMPSs designed solely with discrete devices including bipolar junction transistors (BJTs or bipolars) for the switches. And all of the magnetic components were designed from scratch. These projects required innovation, which would require Severns to develop new circuit topologies and design techniques.
For example, at ATC, Severns introduced a resonant power-supply design for space at a time when most space applications were using flyback converters. In this case, the resonant approach was motivated by the challenge of delivering high voltage at low power (milliwatts), but with very high efficiency. This work became the subject of his second paper.
In this application, Severns says, “You had to supply 20 mW at 400 V from a 28-V spacecraft bus and you had to do it as efficiently as possible. That's extremely difficult to do with hard switching. So I went with the resonant approach, which required some innovation.”
At Hughes, his work with traveling wave tube amplifiers required him to invent circuits that could achieve high efficiency and very light weight. “That's really where I started to invent new circuits and new topologies,” says Severns.
The demand for very light weight together with small size would also be a motivating requirement at Magnavox. “That's where I started doing very-high-frequency work,” says Severns.
In the late '70s, the standard for switchers was 20 kHz to 25 kHz. At Magnavox, Severns pushed the switching frequency beyond 100 kHz, even developing a tiny (for the time) SMPS running at 600 kHz. That work was the basis for two groundbreaking papers that he presented at PowerCon and the Power Electronics Specialists Conference (PESC) in 1978 and eventually led to Severns' appointment as an IEEE fellow.
The PowerCon paper, “Design of High-Efficiency Off-line Converters Above 100 kHz” was one of the earliest to discuss the possibility of higher-frequency operation.
“It was the first real proposal in a large power-supply forum that said, ‘Think about much higher switching frequencies.’” The paper was very popular, even receiving a best paper award, but it was also controversial. Severns recalls that Ron Birdsall, the organizer of the event, suggested that Severns write about something less “blue sky” and more practical for his next conference paper. But within two or three years, high-frequency switching wasn't blue sky anymore.
In addressing the PowerCon audience, Severns took care to explain that high-frequency switching was an option, rather than a necessity in all cases. But this message was not heard.
Severns recalls, “When I presented the paper, I was extremely careful to say, I am not telling you that you should operate at these frequencies. I am telling you that in certain situations you can and you may wish to operate at these frequencies. Of course, within months everyone was saying that I was advocating that we all shift to this frequency.”
Severns notes that in later years, he went so far as to tell designers to decrease switching frequencies when higher-frequency switching wasn't warranted.
At the time Severns presented his paper, the use of SMPS technology was well established within the military and aerospace industries. However, it had not yet been accepted within the commercial industry. It's frequently said that the arrival of the power MOSFET enabled the adoption of switch-mode technology by commercial power-supply merchants in the late '70s and early '80s.
According to Severns, the power MOSFET also enabled the migration to the higher switching frequencies he was describing in his papers. “Almost immediately after I gave my paper, the power MOSFET came on the scene and designers didn't have to go through the effort I did to make BJTs work at 150 or 200 kHz.”
Nevertheless, the transition to higher frequencies did not happen overnight. It would take 10 years before the MOSFETs would become cheap enough that designers would use them en masse and be able to routinely design power supplies to operate at higher frequencies, according to Severns.
Adventures in Semiconductors
When Severns gave his PowerCon paper in San Francisco, the sales manager from Intersil was in the audience. “With some later arm twisting, he dragged me up to go to work for Intersil, because they were simultaneously [along with Siliconix, Hewlett-Packard and International Rectifier] coming out with power MOSFETs.
“Intersil lured me away, but I was easy to lure because it was really different. Developing hardware is one world. The semiconductor industry is another world,” says Severns.
At the time he started working at Intersil as a field applications engineer (FAE), the only design he had completed using a power MOSFET was the 600-kHz switcher described in his PESC paper. “Now I understood the principles, but from principles to writing application notes and giving lectures, it's a long jump.”
However, Severns learned quickly about how MOSFETs work, and how their particular characteristics and flaws could lead to failures in the applications. He then had to instruct customers in how to use the new transistors and how to avoid pitfalls.
“For instance, somebody would put two MOSFETs in parallel and they would start oscillating. That's because these things have gain up in the ultrahigh-frequency region. So my job was to figure out how to prevent that. And there were other strange operating modes having to do with dv/dt,” says Severns.
“The early MOSFETs, for example, they would switch very fast. But when you started doing that with more than one of them in the circuit, a device would be in the off state and have this tremendous dv/dt applied across it. So, the one that was supposed to be off would be turned on due to intrinsic parasitics,” explains Severns.
Severns notes that his counterparts at the other power MOSFET companies were also addressing these problems, though he was among the first to write about dv/dt and other issues such as parasitic oscillation in parallel devices, radiation effects and avalanche-induced turn off. Most of these issues were addressed through semiconductor processing.
“My job was to identify the problem, explain to the world what the problem was and how to avoid it until we fix it right,” says Severns. “And at the same time, I had to tell the device designers in the process department, ‘Change your design so we don't have to tell the world that we have this problem.’”
In 1980, his work as an FAE also gave him his start as a teacher, which included giving presentations to engineers about MOSFETS. “The MOSFET's a new product. We have to sell the engineering community on how to use this product. That's when I started giving lots and lots of seminar talks.”
Though he did this initially for Intersil, he would later present similar seminars for International Rectifier and Siliconix. In time he would expand into teaching power-supply design seminars for Ed Bloom, and for others such as the University of Wisconsin at Madison and Oregon State University.
In Boredom, Inspiration
“In 1980, while working for Intersil, I wrote the first tract on how to invent new topologies. I wrote what's called the kama sutra of power-supply topologies. It's a 40- or 50-page application note full of dozens and dozens of circuits. And a lot of them are new or showing likeness between old ones. The whole idea was here's how you invent power-supply topologies.”
“I had given a couple papers before touching on the subject. Topology invention for me really started when I worked at Hughes and I never let that thread go. So for Intersil, I wrote this humongous application note for SMPS people saying here are all the ways you can use it. Of course, all of the models in there use MOSFETs for switches, naturally. Ed Bloom looked at that application note and said, ‘Couldn't we write a book on that?’”
After that suggestion, some time passed and Severns embarked on his sailing trip to Mexico and Hawaii. Severns notes that normally he could forget about engineering for several months at a time, but that was more difficult to do on such a long voyage.
“So, I'm on my cruise, and it's about seven or eight months into the cruise. I'm in Kane'ohe Bay, Hawaii. I'm sitting in paradise absolutely bored to death. So I say, ‘Ed, I am going to write a book.’ And I sat down with a pencil and a pad of yellow-lined paper on the boat and wrote in longhand everyday for a few hours.”
“And then I just kept mailing these packages to Ed Bloom, one chapter at a time. His wife, Joy, is transcribing on an early Apple computer. She is taking all of this chicken scratch on yellow-lined paper and writing this all up. Then Ed goes through and checks everything.” Out of this work emerged Modern DC to DC Switchmode Power Converter Circuits.
“The book would not have happened without Ed Bloom's efforts. He prodded me to write it. He did a tremendous amount of work, about 80% of the work. And Ed added a chapter 12 on converters with integrated magnetics.”
Severns says he was amazed at the reception the book received. “We have sold several thousand copies, and it has been translated illegally into several languages. It's not the world's greatest technical book at all, it's just sort of a show and tell,” says Severns. “But the main comment I got back was how easy it was to read and create new ideas from. That was part of the reason for its success. The other part was that there was nothing like it other than the application note I had written at Intersil.”
“Engineers working in the field were choosing power-supply topologies from a very, very narrow set at the time, and we just wanted to jog them a little bit. Now, given the experience over the past 25 years since the book was written, having hundreds of circuits has only had a small impact on the field,” comments Severns. “People are still using the same relatively small set of topologies for large commercial activities (i.e., high-volume, low-cost products). The book really had its impact in more specialized military, space and medical applications.”
At the time he wrote the book on topologies, Severns was well into his career as an independent consultant. In that role, he continued to give seminars, write papers and participate in industry conferences.
New Engineering Challenges
A few years ago, Severns took down his consulting shingle and retired. But for Severns, retirement has given him an opportunity to pursue his interests in amateur radio more intensively. His involvement with power electronics and amateur radio, he believes, are closely linked.
“Certainly for me, they're one item, a single thread, really. All of my early work stems from being a teenager trying to build a transmitter. That's all analog, and with transmitters you're immediately into high voltage and high power. Today, the theme continues as I'm doing a lot of experimental electromagnetics work in antennas.”
Severns has been busy publishing his results in various amateur radio magazines and also on his Web site. But ultimately, he'd like to make a contribution to the amateur radio field by writing a book in which he explains details surrounding the operation of vertical antennas, grounds and ground antennas. Within these topics there are issues that have either been “misexplained, ignored or are matters of contention,” says Severns.
To support these endeavors, Severns has gone back to school. For the last four years, he has been taking courses in mathematics and electromagnetics at the University of Oregon to bring himself up to speed on the field.
And despite his attempts to retire from power electronics, just this year he completed a book on snubber design at the urging of Jerrold Foutz, a longtime industry veteran. The book, Snubber Circuits for Power Electronics, explores an area of power-supply design that is absolutely critical in high-power applications.
And while he views himself as being out of the power electronics business these days, Severns may yet take some of the knowledge he has “salted away” and write additional books on power design topics. If he does, it will be another opportunity for Severns to influence future generations of engineers working in the power electronics field.
With demands for energy efficiency driving technology development and applications like smart power grids emerging, Severns believes “power electronics is alive and well.”
“There's a whole field available to young engineers,” says Severns. “Everywhere I look, I see opportunities.”
Publications by Rudy Severns*
- Coelle, Severns and Turner, CROSSING HIGH VOLTAGE INTERFACES WITH LARGE BANDWIDTH SIGNALS, IEEE Particle Accelerator Conference Proceedings, Washington DC 1967
- Severns, HIGH VOLTAGE SUPPLIES, 24th Power Sources Symposium Proceedings, May 1970, Atlantic City, NJ
- Severns, USER PERFORMANCE REQUIREMENTS FOR MINI-COMPUTER POWER SUPPLIES, 1976 WESCON Professional Program, Session 2
- Severns and Sommers, DESIGN OF HIGH EFFICIENCY OFF-LINE CONVERTERS ABOVE 100 kHz, Proceedings of PowerCon 5, May 1978, pages G2-1 through G2-7
- Severns, HIGH FREQUENCY SWITCHING REGULATOR TECHNIQUES, IEEE Power Electronics Specialists Conference (PESC) record, June 1978
- Severns, A NEW IMPROVED AND SIMPLIFIED PROPORTIONAL BASE DRIVE CIRCUIT, Proceedings of PowerCon 6, May 1979, pages B2-1 through B2-11
- Severns, A NEW CURRENT FED CONVERTER TOPOLOGY, IEEE PESC record, June 1979, San Diego
- Severns, TECHNIQUES FOR DESIGNING NEW TYPES OF SWITCHING REGULATORS, Power conversion International Conference (PCI) record, September 1979, Munich
- Severns, THE POWER MOSFET, A BREAKTHROUGH IN POWER DEVICE TECHNOLOGY, Intersil Applications note A033, January 1980
- Severns, MOVING FROM 20 kHz TO OVER 200 kHz OPERATIONS PUTS MORE PUNCH IN SWITCHER PERFORMANCE, Electronic Design, Vol. 2, January 18, 1980, pages 74-78
- Severns, SWITCHMODE CONVERTERS ABOVE 100 kHz, Intersil applications note A034, February 1980
- Severns, SWITCHMODE TOPOLOGIES - MAKE THEM WORK FOR YOU, Intersil applications note A035, February 1980
- Severns, COMPONENT SELECTION WEIGHS HEAVILY IN HIGH FREQUENCY SUPPLIES, Electronic Design, Vol. 3, February 1, 1980, pages 85-88
- Severns, POWER MOSFETS TAKE AIM AT SWITCHING SUPPLIES, Electronic Products, March 1980, pages 75-78
- Severns, CAPACITORS AND INDUCTORS LEAD THE WAY TO COMPACT, HIGH FREQUENCY SWITCHERS, Electronic Design, Vol. 5, March 1, 1980
- Severns, HIGH FREQUENCY SWITCHES GET THE NOD WHEN TOP PERFORMANCE COUNTS MOST, Electronic Design, Vol. 7, March 29, 1980
- Severns, THE POWER MOSFET AS A RECTIFIER, PCI magazine, March/April 1980, pages 49-50
- Severns, USING THE POWER MOSFET AS A SWITCH, Intersil applications note A036, May 1980
- Severns, MOSFETS RISE TO NEW LEVELS OF POWER, Electronics, May 22, 1980
- Severns, THE EFFECT OF SECONDARY LEAKAGE AND RECTIFIER CONNECTION INDUCTANCE ON THE OUTPUT REGULATION IN SWITCHING REGULATORS, International Power Conversion Society newsletter, Summer 1980
- Bloom and Severns, UNUSUAL DC-DC POWER CONVERSION SYSTEMS, 1980 MIDCON professional program
- Severns, SWITCHMODE AND RESONANTCONVERTER CIRCUITS, International Rectifier Corp. applications note, March 1981
- Severns, SIMPLIFIED HEXFET POWER DISSIPATION AND JUNCTION TEMPERATURE CALCULATION SPEEDS HEAT SINK DESIGN, MOTORCON 1981, May, paper 5A.3
- Severns, dV/dt EFFECTS IN MOSFET AND BIPOLAR JUNCTION TRANSISTOR SWITCHES, IEEE PESC record, June 1981, pages 258-264
- Severns, SIMPLIFIED HEXFET POWER DISSIPATION CALCULATION, International Rectifier Corp., applications note 942, June 1981
- Blanchard and Severns, DESIGNING SWITCHED, MODE POWER CONVERTERS FOR VERY LOW TEMPERATURE OPERATION, PowerCon 10, 1983 section D2
- Severns, SAFE OPERATING AREA AND THERMAL DESIGN FOR MOSPOWER TRANSISTORS, Siliconix applications note AN83-10, November 1983
- Severns, SWITCHMODE POWER SUPPLY DESIGN USING A PERSONAL COMPUTER, PCI magazine, Nov/Dec 1983, page 39
- Bloom and Severns, MODERN DC TO DC SWITCHMODE POWER CONVERTER CIRCUITS, Van Nostrand Rheinhold, 1984
- Blanchard and Severns, MOSFETS MOVE IN ON LOW VOLTAGE RECTIFICATION, Siliconix applications note TA84-2, 1984
- Bloom and Severns, THE GENERALIZED USE OF INTEGRATED MAGNETICS AND ZERO-RIPPLE TECHNIQUES IN SWITCHMODE POWER CONVERTERS, IEEE PESC84 proceedings, June 1984, pp. 15-33
- B. Bloom and Severns, MAGNETIC INTEGRATION METHODS FOR TRANSFORMER ISOLATED BUCK AND BOOST DC-DC CONVERTERS, PowerCon 11, 1984
- Blanchard and Severns, CONCEPTION D'UNE ALIMENTATION A DE'COUPAGE POUR FONCTIONNEMENT A ULTRA-BASSE TEMPERATURE, Electronique De Puissance-3, France, February 1984, pages 48-55
- Severns, dVds/dt TURN-ON IN POWER MOSFETS, Siliconix applications note TA84-4, April 1984
- Severns, MOSFETS AND RADIATION ENVIRONMENTS, Siliconix applications note TA84-3, April 1984
- Blanchard and Severns, PRACTICAL SYNCHRONOUS RECTIFICATION USING MOSFETS, PowerCon 11, April 1984, withdrawn
- Blanchard and Severns, REDRESSEMENT SYNCHRONISE UTILISANT DES MOSFETS, Electronique De Puissance-4, France, April 1984
- Severns, PARALLEL OPERATION OF POWER MOSFETS, Siliconix applications note TA84-5, June 1984
- Bloom and Severns, THE GENERALIZED USE OF INTEGRATED MAGNETICS AND ZERO RIPPLE TECHNIQUES IN SWITCHMODE POWER CONVERTERS, IEEE PESC record, June 1984
- Blanchard and Severns, MOSFETS, SCHOTTKY DIODES VIE FOR LOW VOLTAGE SUPPLY DESIGNS, EDN magazine, June 28, 1984, pages 197-205
- Corbett and Severns, POWER ELECTRONICS IN SPACE - A REVIEW AND PROJECTION, IEEE AESS Transactions, July 1984
- Severns, ANALYZING THERMAL STABILITY IN MOSPOWER TRANSISTORS, New Electronics magazine, UK, October 30 and November 13, pages 114-121
- Severns, AVOIDING SPURIOUS MOSFET TURN-ON, Electronic Engineering magazine, UK, November 1984, pages 51-57
- Severns (editor), MOSPOWER APPLICATIONS HANDBOOK, Siliconix Inc., 1984
- Severns, AVOIDING dV/dt TURN-ON IN POWER MOSFETS, Electronic Products magazine, January 15, 1985, pages 89-94
- Severns, REVERSE RECOVERY AND MODE 3 dV/dt TURN-ON IN MOSFETS, Electro '85 technical paper, April 1985
- Severns, PARALLEL OPERATION OF MOSFETS IN DC-DC CONVERTERS, Power Technics magazine, June 1985, pages 16-20
- Blanchard and Severns, THE USE OF MOSFETS IN HIGH DOSE RATE ENVIRONMENTS, IEEE Applied Power Electronics Conference (APEC) proceeding, April 1986, pages 8-12
- Cogan, Fortier and Severns, A HIGH EFFICIENCY MOSFET USED AS A CONTROL ELEMENT IN AN 800 V SWITCH, IEEE APEC proceedings, April 1986, pages 35-40
- Severns, IMPROVING AND SIMPLIFYING HF DC CURRENT SENSORS, IEEE APEC proceedings, April 1986, pages 180-183
- Blanchard, Cogan, Fortier and Severns, SPECIAL FEATURES OF POWER MOSFETS IN HIGH FREQUENCY SWITCHING CIRCUITS, High Frequency Power Converter Conference (HFPC) proceedings, May 1986, pages 133-148
- Severns, NEW TOPOLOGIES FOR DC-AC POLYPHASE PWM INVERTERS, Power Electronics Conference (PEC) proceedings, February 1988
- Severns, SUPERCONDUCTIVITY AND LOW TEMPERATURE POWER CONVERTERS, Power Technics magazine, April 1988, pages 32-34
- Severns, GENERALIZED TOPOLOGIES FOR CONVERTERS WITH REACTIVE ENERGY STORAGE, IEEE IAS conference record, October 1989, pages 1145-1151
- Severns, TOPOLOGIES FOR THREE ELEMENT RESONANT CONVERTERS, IEEE APEC conference record, 1990
- Severns, HIGH FREQUENCY CONVERTERS WITH NON PULSATING INPUT AND OUTPUT CURRENTS, HFPC '90 conference record, 1990
- Severns, HF CORE LOSSES FOR NON-SINUSOIDAL WAVEFORMS, HFPC '91 conference record, Toronto, 1991
- Severns, A SIMPLE, GENERAL METHOD FOR CALCULATING HF WINDING LOSSES FOR ARBITRARY CURRENT WAVEFORMS, HFPC '91, Toronto, 1991
- Severns, TOPOLOGIES FOR THREE ELEMENT RESONANT CONVERTERS, IEEE Transactions on Power Electronics, Vol. 7, Number 1, January 1992, pp. 89-98
- Severns, ADDITIONAL LOSSES IN HIGH FREQUENCY MAGNETICS DUE TO NON IDEAL FIELD DISTRIBUTIONS, IEEE APEC'92, February 1992, Boston
- Batarseh and Severns, RESONANT CONVERTER TOPOLOGIES WITH THREE AND FOUR ENERGY STORAGE ELEMENTS, High Frequency Power Conversion conference, May 1992
- Severns and Wittlinger, HIGH FREQUENCY POWER CONVERTERS, Harris Semiconductor applications note AN9208
- Severns, R., FINITE ELEMENT ANALYSIS IMPROVES ACCURACY OF HIGH FREQUENCY POWER CONVERTER MAGNETICS CALCULATIONS, PCIM magazine, April 1993, pp. 27-29
- Severns, R., SOFTWARE CALCULATES HIGH-FREQUENCY WINDING LOSSES, EDN magazine, April 15, 1993, pp. 304-306
- Severns, R., FINITE ELEMENT ANALYSIS IN POWER CONVERTER DESIGN, IEEE APEC'94 conference record, February 1994, pp. 3-9
- Severns, R., N6LF, AN IMPROVED DOUBLE EXTENDED ZEPP, American Radio Relay League (ARRL), Antenna Compendium, Vol. 4, 1995, pp. 78-80
- Severns, R., N6LF, A WIDEBAND 80-METER DIPOLE, QST magazine (ARRL), July 1995, pp. 27-29
- Severns, Yeow, Woody, Hall and Hayes, AN ULTRA-COMPACT TRANSFORMER FOR A 100 W TO 120kW INDUCTIVE COUPLER FOR ELECTRIC VEHICLE BATTERY CHARGING, IEEE APEC 96 proceedings, March 1996
- Severns, R., N6LF, USING THE HALF-SQUARE ANTENNA FOR LOW BAND DXING, ARRL Antenna Compendium, Vol. 5, 1996
- Severns, R., N6LF, BROADBANDING THE HALF-SQUARE ANTENNA FOR 80 M DXING, ARRL Antenna Compendium, Vol. 5, 1996
- Severns, R., CIRCUIT REINVENTION IN POWER ELECTRONICS AND IDENTIFICATION OF PRIOR WORK, IEEE APEC conf. record, February 1997, pp. 3-9
- Sandler, Steven M., SMPS SIMULATION WITH SPICE 3, McGraw-Hill, New York, 1997, R. Severns, contributing author for magnetics modeling chapter
- Straw, Dean, THE ARRL ANTENNA BOOK, 18th edition, American Radio Relay League, May 1997, R. Severns contributing editor chapters 4, 6 and 16
- Severns, R., THE LAZY-H VERTICAL, Communications Quarterly, Spring 1997, pp.31-40
- Severns, R., ADVANTAGES OF AN ALTERNATIVE VIEWPOINT WHEN DESIGNING HF VERTICAL FOR 80 AND 160 M, Applied Computational Electromagnetics Society proceedings of the annual meeting, March 1998
- Severns, R., ANOTHER WAY TO LOOK AT VERTICAL ANTENNAS, ARRL QEX magazine March/April 1999, pp. 3-8
- Severns, R., MONSTER QUADS, ARRL Antenna Compendium 6, 1999, pp. 113-118
- Severns, R., SHORT RADIALS FOR GROUND-PLANE ANTENNAS, ARRL Antenna Compendium 6, 1999, pp. 212-215
- Severns, R., VERTICALS, GROUND SYSTEMS AND SOME HISTORY, QST magazine, ARRL, July 2000, pp. 38-44
- Severns, R., THE HISTORY OF THE FORWARD CONVERTER, Switching Power Magazine, July 2000, Volume 1, issue 1, pp. 20-22
- Severns, R., N6LF, ANTENNAS WITH GAIN AND BANDWIDTH FOR 80 AND 160 m, National Contest Journal, Vol. 28, No. 5, ARRL, Sept/Oct 2000, pp. 14-16
- Severns, R., CONDUCTORS FOR HF ANTENNAS, QEX magazine, ARRL, Nov/Dec 2000, pp. 20-29
- Severns, R., CIRCUIT REINVENTION IN POWER ELECTRONICS AND IDENTIFICATION OF PRIOR WORK, IEEE transactions on Power Electronics, Vol. 16, No. 1, January 2001, pp. 1-7
- Severns, R., HISTORY OF SOFT SWITCHING, Switching Power Magazine, January 2001, Vol. 2, No. 1, pp. 18-20
- Severns, R., HISTORY OF SOFT SWITCHING, part II, Switching Power Magazine, Fall 2001, Vol. 2, No. 4, pp. 12-15
- Severns, R., RESISTANCE OF FOIL CONDUCTORS FOR ANTENNAS, QEX magazine, May/June 2002, Tech Notes, pp. 55-56
- Severns, R., N6LF, SINGLE SUPPORT GAIN ANTENNAS FOR 80 AND 160 METERS, National Contest Journal (NCJ), ARRL, Vol. 31, No. 2, Mar/Apr 2003, pp. 12-17
- Severns, R., GETTING THE MOST FROM HALF-WAVE SLOPER ARRAYS, QEX magazine, Jan/Feb 2004, pp. 32-41
Books by Rudy Severns*
- Severns, Rudy, Snubber Circuits for Power Electronics, ebook in PDF format, 346 pp., April, 2008
- Severns, R. P., and G. Bloom, Modern DC-DC Switchmode Power Conversion Circuits, New York : Van Nostrand Reinhold Co., c 1985. xvii, 342 p. : ill. ; 24 cm. ISBN: 0442213964, LC Control Number: 84-12026, TK7868.P6 S47 1985 (out-of-print)
- Severns, R., and J. Armijos, (editors) MOSPOWER Applications, Siliconix Inc., 1984. Siliconix Inc., 2202 Lourelwood Road, Santa Clara, CA 95045, (408) 988-8000. (out-of-print)