MOUNTAIN VIEW, CA, September 12, 2017
The Marconi Society, dedicated to furthering scientific achievements in communications and the Internet, will honor Negar Reiskarimian, a fourth-year PhD student at Columbia University, with a 2017 Marconi Society Paul Baran Young Scholar Award for her work on non-reciprocal microwave components for new wireless communication paradigms.
Reiskarimian’s research has focused on the fundamental physical principles and the engineering applications of breaking Lorentz Reciprocity, which allows signals to be routed in new ways, enabling new wireless communication applications. Her advisor, Associate Professor Harish Krishnaswamy, calls it “the highest-impact research that I have had the privilege of participating in throughout my career.” The work has garnered nearly $4.5M of research funding from NSF, DARPA and through industrial funding from Qualcomm and Texas Instruments.
Lorentz Reciprocity essentially states that signals must travel in the same fashion in forward and reverse directions. However, this places severe restrictions on wave propagation, and the components that can be engineered. For example, the circulator, a component that allows a transmitter and a receiver to operate at the same time on a shared antenna, requires the breaking of reciprocity so that the transmitter and receiver signal can be routed differently and separated. Such a component would enable two-way or “full-duplex” wireless, where transmitters and receivers work at the same time at the same frequency, a form of wireless communications that has been historically thought to be impossible and has the potential to double wireless capacity immediately.
Reiskarimian made a critical discovery in early 2015, as she was trying to find new applications for N-path filters, which are RF time-varying switched-capacitor circuits that have been around since the 1950s. The filters were mostly ignored until 2010, when scientists realized that with the availability of modern CMOS technologies N-path filters could be put on silicon chips, providing reconfigurable, high quality factor RF filters.
“I’ve always been interested in circuit design, but in recent years it is becoming harder and harder to come up with new original ideas in this area,” Reiskarimian says, “The IC fabrication technology hasn’t been getting that much better every year especially for RF applications, and a lot of research efforts are focused on trying to squeeze a little bit more performance out of the existing designs. What I wanted to do is find completely new applications for the circuits and tools at my disposal.”
“A colleague of mine was working on integrated full duplex radios, and through this I became aware of the challenges involved in designing antenna interfaces for full-duplex radios and the need for on-chip nonreciprocal components such as circulators which depend on breaking Lorentz Reciprocity.” She started by reviewing several papers on the N-path circuits. The N-path circuits didn’t directly solve the problem, but as she was playing around with one, she stumbled upon a new functionality in the structure that might do the trick. If the switches on either side of the capacitor were staggered in time, the circuit exhibited a gyrator response—a fundamental non-reciprocal circuit element that can be used to create arbitrary non-reciprocal circuits, such as circulators.
It was an important breakthrough, and she realized it could have a wide range of applications in wireless communications, radars, optics, and much more. With DARPA funding, she built a prototype chip, and wrote a paper on the physical principles behind the work that was published in Nature Communications. A full-duplex receiver using her circulator was reported at IEEE ISSCC 2016 followed by publication in the IEEE Journal of Solid-State Circuits.
Since then, Reiskarimian has been awarded a 2016 Qualcomm Innovation Fellowship, the 2016-2017 SSCS Pre-Doctoral Achievement Award, the ADI 2017 Outstanding Student Designer Award, a 2017 IEEE MTT-S Microwave Engineering Graduate Fellowship, and a 2017 Caltech Young Investigator Lectureship. Commercial interest in the invention has been significant.
Reiskarimian, an Iranian native, is the daughter of a civil engineer and a psychologist who were fierce education advocates. She graduated from Sharif University, the top school for engineering in Iran, earning her master’s degree there before applying to Columbia. Ultimately, she hopes to teach, as well as to continue her research, seeking new and interdisciplinary applications for integrated circuits and systems.
“I am humbled and honored to be chosen for the Paul Baran Young Scholar Award,” she says. “It is a bit easier to be known in your own area, but the fact that my work in circuits translates to broader audiences in the communications arena makes me very proud. It gives me assurance that I’m moving in the right direction.”
Young Scholar candidates are nominated by their academic advisors. Winners are selected by an international panel comprised of engineers from leading universities and companies, and receive a $4000 prize plus expenses to attend the annual awards event. Three other Young Scholars were also selected this year.
Reiskarimian will receive her award at the same event where former Bell Labs chief Arun Netravali, regarded as the “father of video,” will be honored with the $100,000 Marconi Prize.
About the Marconi Society
Established in 1974 by the daughter of Guglielmo Marconi, the Nobel Laureate who invented radio, the Marconi Society promotes awareness of key technology and policy issues in telecommunications and the Internet, and recognizes significant individual achievements through the Marconi Prize and Young Scholar Awards. More information may be found at www.marconisociety.org. Follow: Twitter and Facebook
