High frequency systems

"A nice surprise"

Prof. Hatt, President of the North Rhine-Westphalian Academy of Sciences and Humanities and speaker Prof. Hartmann, Secretary of the Class for Engineering and Economic Sciences with prize winner Prof. Pohl (center).
© Photo Fraunhofer FHR

Prof. Hatt, President of the North Rhine-Westphalian Academy of Sciences and Humanities and speaker Prof. Hartmann, Secretary of the Class for Engineering and Economic Sciences with prize winner Prof. Pohl (center).

A team of FHR scientists develops highly integrated radar-on-the-chip on a silicon-germanium basis.
© Photo Fraunhofer FHR

A team of FHR scientists develops highly integrated radar-on-the-chip on a silicon-germanium basis.

As a doctoral student, he jokingly constructed a radar-based measuring system which could play Christmas songs by varying the measurement distances. Today, Nils Pohl is one of the best early-stage researchers in North Rhine-Westphalia and a department head at Fraunhofer FHR.

Prof. Pohl, you have served as the Head of the Department for Millimeter Wave and Ultra-high Frequency Sensors since 2013. At the same time, you are also a junior professor at the Ruhr University in Bochum.

Pohl: Yes, but I have been given leave from my professorship so that I can concentrate on my duties as department leader. I do, however, plan to cultivate the contact with the universities. For one, the basic research conducted there can be seen as an important contribution and secondly, I enjoy giving lectures.

You studied at the Ruhr University. What exactly did you study?

Pohl: I studied electrical engineering and information technology, did my diploma in 2005 and then continued with my doctoral studies. During my studies I already focused on high frequency technology and chip design.

Chip design also played a major role in your doctoral degree?

Pohl: Correct. I focused exclusively on chip design. My aim was to develop a radar system which could, for example, record the liquid level in industrial liquid tanks. I developed a number of interesting circuits during this time. With a few tricks, I even realized ultra wideband oscillators. This forms the basis for very high resolution radar systems.

In 2011, as a junior professor, you were appointed to the Chair for Integrated Systems at the University of Bochum.

Pohl: As a junior professor you have quite a lot of freedom and therefore a great chance to approach the theme and conduct research on it in any manner you wish. At that time, I conducted further research on the themes from my doctoral degree and focused my attention on the development of chips on a silicon-germanium (SiGe) basis and also used these in various radar applications.

Previously, chips were mainly produced on a silicon or gallium arsenide basis. What are the advantages of SiGe chips?

Pohl: Originally, silicon chips were designed purely for digital applications, as we know from computers. The first SiGe chips were developed at the end of the 1990s and the first radar systems with SiGe chips were produced in 2004. The automotive industry played a pioneering role here. The combination of silicon and germanium paved the way for very high switching frequencies, as are needed in the area of high frequency technology. We can now design highly integrated radar systems which are compact, suitable for mass production and hence highly cost-effective.

You recently received the Karl Arnold Prize from the North Rhine-Westphalian Academy of Sciences and Humanities for your work in this area.

Pohl: Oh yes, that was a bit of a surprise! A nice surprise of course. One day I got a phone call where I learned that I had not only been nominated for the prize, but had also won it. Those who nominated be and, the jury too obviously, were very impressed with my solution for miniaturizing a radar. The had come across something that was new, forward-looking and technically elegant.

Are you still conducting research on SiGe chips?

Pohl: Oh yes!  I am convinced, as is the institute, that SiGe technology is a valuable addition to the FHR portfolio. Last month, we set up a team that will focus exclusively on chip design. The first chips are already in production and we will receive these in a couple of weeks. We are eager to see the outcome.

What will be chips be used for?

Pohl: We are still in the early days. Despite the progress in the last years, the development of a radar-on-the-chip is still a huge challenge. But we aim to develop complex multi-channel systems which can be used, for example, in quality control and production. Here, THz line scan cameras can supply high-precision results and images at belt speeds of several meters per second.