Design of Active and Passive Components for the Implementation of an Ultra-Broadband Wireless Communication System at 200 GHz

This research thesis studies the properties and limits of circuits and complete transmission systems around very high frequencies at 200 GHz. Corresponding basic research challenges are discussed and profound knowledge gain is achieved by covering a wide range from theoretical aspects, device modeling and novel concepts up to feasibility studies by means of hardware implementations. The latter include interface, packaging and assembly issues, as well as approaches for the characterization in the laboratory. Here, one of the main goals is to achieve a high bandwidth for each individual component. To prove the presented concepts, a full functional link is realized by systematically applying novel theoretical and practical approaches to overcome existing problems in a variety of disciplines. One of the most advanced SiGe BiCMOS processes, with an f max of up to 450 GHz, is used for the implementation. Optimizations at layout level and for the characterization procedure, are derived specifically for this technology, which contribute significantly to the overall achieved system performance.

Among others, a passive method is developed for creating high-efficiency 3D onchip monopole antennas by means of conventional wire-bonding. This technique is further refined for packaging circuits directly into self-designed waveguide modules. In addition to the passive solutions, up to 12 chips from 7 individual designs are involved in the assembly of the test setup. This includes a transmitter and a receiver with 80 GHz RF bandwidth, a 180 GHz frequency quadrupler with more than 52 dB harmonic rejection, a low-noise amplifier with 7.1 dB noise figure, a power amplifier saturated at 15 dBm and a limiting amplifier with 25.4 THz gain-bandwidth product. In regard to the main metrics, each of these blocks represent or extends the current state-of-the-art. Additionally, the simulations and theoretical investigations are in excellent agreement with the measurement results.

The setup for the final feasibility study consists of several compact modules with standardized coaxial interfaces and shows an operational wireless link over a distance of 1.5 m with a data rate of 60 Gbit/s for BPSK and 40 Gbit/s for QPSK modulation. An analysis of the occurring issues, which reduced the maximum achieved performance in the QPSK mode are presented and discussed in detail, revealing further research potentials for the future. Compared to the state-of-the-art this system offers one of the largest symbol rates for BPSK in combination with high output power and large range.