InP DHBT and SiGe BiCMOS MMIC Design for THz Signal Generation

Unlike in the lower millimeter wave region or in the infrared region, there is no technology enabling an efficient source design in the terahertz region. Therefore, an efficient generation of terahertz waves has been a subject of many research works. Especially over
the past decade, the studies on this subject have gained momentum with the demonstration of the newest technologies. Allowing an easy integration with the high-density digital circuits having a massive amount of computational power, transistor technologies
are the most promising ones invading the lower end of the terahertz region. First of all in this dissertation, properties of the terahertz waves and emerging applications are described. Due to the inherent properties of the terahertz waves, all the emerging applications are short-range applications. It is concluded that the exploitation of the terahertz region for the future mobile wireless networks, such as 6G, is only feasible if a ton of cells are constructed. Afterwards, enabling technologies are introduced. Then, the transistor technologies used for this dissertation are presented in detail, namely FBH’s InP DHBT and IHP’s SiGe BiCMOS technologies. Circuit designs constitute the main part of this dissertation. Monolithic microwave integrated circuits operating at terahertz frequencies based on the these transistor technologies are demonstrated. These are active as well as passive circuits including frequency multipliers, power amplifier, on-chip antennas, and balun designs which are the essential components of microwave sources. Two types of unbalanced and four types of balanced frequency multipliers based on the InP DHBT technology are presented in this dissertation. The EM simulations show that an unbalanced frequency doubler can reach up to 5 dBm of output power with a 3 dB frequency band of 250-320 GHz. Another unbalanced frequency doubler is integrated with a patch antenna operating at 560 GHz. It provides -17.2 dBm of radiated output power at this frequency. Balanced frequency doublers with a Marchand balun and an active balun provide the largest 3 dB frequency band, from 220 GHz to 320 GHz. They can reach up to 3.8 dBm and 3 dBm of output power, respectively. Another frequency doubler is designed using a ratrace hybrid coupler. It can reach up to 3.4 dBm of output power at 280 GHz, having a narrower 3 dB bandwidth. A balanced frequency tripler is also demonstrated, providing -1.8 dBm of output power at 260 GHz. There are three types of SiGe BiCMOS based circuits demonstrated in this dissertation. Two of them are frequency multipliers and the other is a power amplifier. The frequency multipliers have the same novel self-mixing frequency tripler topology. It is a compact and flexible topology allowing an easy optimization of the output power depending on the available input power level. The first frequency multiplier design operating at 220-330 GHz provides a measured output power of 3 dBm at 280 GHz. The second one is integrated with a patch antenna operating at 550 GHz. EM simulations show that it can provide a radiated output power of -4.8 dBm. The power amplifier provides a small-signal gain of 17 dB and a saturated output power of 4 dBm at 280 GHz according to the EM simulations. Measurement results are also provided for the power amplifier. On-chip antennas based on the InP DHBT technology operating at mm-wave are also demonstrated. According to the EM simulations, a Vivaldi antenna providing a large bandwidth demonstrates a directivity of approximately 7 dBi with a total efficiency of -1.85 dB at 275 GHz. A cavity backed slot antenna provides a directivity of 5.4 dBi with a total efficiency of -1.75 dB at 275 GHz. A patch antenna demonstrates a directivity of 7.1 dBi with a total efficiency of -4.7 dB at 319 GHz. The measured input reflection coefficient of the patch antenna is also given, which agrees well with the EM simulation results at 280-325 GHz. After the circuits are presented, finally, a comparison of the transistor technologies used for this dissertation and suggestions for further studies are given.