Eridan’s history can really be summed up by saying that it took the serendipitous combination of three minds coming together to create a new technological innovation. It was Earl McCune’s expertise in polar transmitters, Dubravko Babic’s knowledge and experience with Gallium Nitride, and Doug Kirkpatrick’s ability to fill in the gaps that led to the creation of the MIRACLE module. This combination of Gallium Nitride with direct polar architecture in radio technology has enabled a new level of energy efficiency, spectral density and tunability with over 29 patents issued and pending.
Recently we sat down with Doug and Dubravko and let them tell the more detailed story of discovering the combination of Gallium Nitride and direct polar architecture, and how they realized that what they found was nothing short of revolutionary.
Dubravko: GaN (gallium nitride) is a wonder material in that transistors in GaN can be modulated at power much faster than silicon because its breakdown voltages and current carrying capabilities exceed that of silicon transistors many times. These characteristics of GaN make it ideal for high power radiofrequency and microwave devices, with the exception of the heat conductivity of the substrates on which these transistors were made.
I was working as a VP of Technology at Group4 Labs which started doing this thing in 2008: they came up with a method to integrate gallium nitride (GaN) with synthetic diamond. The idea was that diamond would enable even higher power performance of GaN, unlocking approaches untouchable by silicon. Now, diamond is the best heat conductor known to man, so combining the two would make the world’s best field-effect transistor for radiofrequency applications.
During 2009, Earl started consulting for Group4 Labs on questions related to the application of high power radio frequency amplifiers. This is where I met Earl. He spoke of polar amplifiers and I had no clue what a polar amplifier or modulator was at that time. Nobody did! Earl had started a company trying to commercialize polar modulators in the 90’s. He did not succeed in this when they were limited to silicon and gallium arsenide, but was convinced GaN was the right material for making polar modulators. So, Group4 Labs thought that a spin-off company by the name of Paragon Devices could make such amplifiers using GaN on diamond technology. They went to Kleiner-Perkins venture capital firm on Sand Hill Road to discuss this with some of the partners. K-P liked the idea, but needed some technical due diligence done and also thought that Paragon Devices needed an outside CEO. This is where Doug comes in.
Doug: As soon as I was brought in to understand the polar amplifier built on GaN on diamond concept, it felt risky. Nobody had yet commercialized polar, and they had tried, and nobody had yet commercialized the GaN on diamond wafers. Risk on top of risk didn’t feel like the right approach.
Dubravko: To investigate this, Doug needed to put down an operational plan for a chip making company. To assist this effort, they called the only electrical engineer from Group4 Labs that knew something about amplifiers: me. That’s how Doug and I met. We sat down for weeks, talking and planning about how we are going to do this. Note that Earl was not a part of this initial discussion.
Doug: We all started to realize that the risk of gallium nitride on diamond may not be necessary. I checked with Cree (now Wolfspeed) that certain specifications of their gallium nitride were good enough. It became clear that with “good enough” gallium nitride and Earl’s direct polar, there could be something real here.
Dubravko: However, in the midst of this development, Group4 Labs ran out of cash and folded. All the remaining assets were acquired by Element Six, Inc. Suddenly it had all stopped and Doug and I found ourselves in a vacuum. I remember sitting at a cafe on Sandhill Road and I said, “You know, we could do this without diamond.” Following this, in Spring 2013, I introduced Earl and Doug to each other and then flew back to Croatia. The two of them worked on a plan by the time I got back to California.
Doug: This is where it all started. But Earl was insistent on two things: “If it’s not a handset, who’s going to pay for it?” and that we would never be able to do 4G signals.
I called my contacts at DARPA. Having been in the field with special forces, I realized that a single radio that tunes over all relevant military bands could be very appealing to the military. Large contracts (tens of billions) were currently being signed for heavy, hot, and limited-tunable radios. One model sold for $200k and it SUCKED. Integrated into a “backpack” with four other radios [one for each frequency band], I could have been asked to carry roughly 80 lbs in radios and batteries. I knew that if we could just build a tunable radio that was more efficient than any of those radios, the military would pay for it.
So I told Earl, “Well that’s great. We’re going to do a small military radio company and we’ll get bought out.” We got a 2-year, $5M exploratory contract with DARPA and started running.
Born in August 2013, Eridan would be a small company making military radios. Jumping forward two years, full-contact engineering led to a new discovery.
This is summer of 2014 in the Homestead Road building, when the DARPA Money came in and we officially hired the first employees (from left to right): Doug, Rick Booth, Earl McCune, Dubravko, Chandra Khandavalli, Quentin Diduck, and Marnie Dunsmore.
Doug: As a team (pictured above), we felt very comfortable challenging each other all the time. We were in a very, very rapid development phase. All the arguments happened in our conference room, and we wore that whiteboard out (picture below). As a part of the dynamic of the company, we would get up and we would have…what would you call it?
Dubravko: *grinning* debates.
Doug: Debates. And they were energetic! It was a full-contact sport. We were all learning so fast.
I still remember this argument with Earl. We were in that conference room with the whiteboard and I was having difficulty with him. I said, “Earl, help me understand why we can’t do 4G”. He started showing me curves and giving explanations. I suggested putting an attenuator in the middle of our amplifier and was met with: “That’s the stupidest god damn thing I’ve ever heard of.” And then Earl interjected, saying “I agree. But then again, it just might work.”
We tried the “stupidest god damn” suggestion and three hours (and a few beers) later, we had produced a fully formed 4G signal. We all sat there and I’m not sure who said it, but one of us said “Oh f*ck.” We had just realized we were no longer [just] a military device company. Now capable of producing commercial signals, we had to change how we were thinking about this.
Being the first to combine Gallium Nitride and direct polar architecture is what started Eridan’s success. Almost eight years later, Eridan has grown 10x, is en route to commercial production, and is capable of producing 2G, 3G, 4G, and 5G signals. Vigorous debate and white-board destroying activities are still a cornerstone of Eridan’s engineering progress today.