Analysis and Design of Bidirectional Integrated Transceivers for 5G Communication Systems

5G communication systems promise to revolutionize the wireless communication world by allowing higher speed links with reduced latency. This improved performance is required by internet of things (IoT) applications where many devices share information with each other. The spectrum allocation is quite crowed in the low GHz frequency ranges and it can not sustain a similar data flow. The new 5G standard explores new frequency ranges, in particular the mmWave spectrum, to improve link capacity. In the last decade, both industries and research institutes put a lot of efforts in the developement of the infrastructure network working at these operating frequencies. New challenges such as wide modulation bandwidth, beam-forming ad massive MIMO have attracted the attention of the scientific community. In particular, the adoption of mmWave frequency moves towards the realization of fully integrated beam-forming systems. This works belongs to this research field by investigating new architectural solutions and circuit topologies. Ultra-scaled CMOS is the enabling technology in this field because it allows large scale production of 5G devices with restrained costs. The Ph.D activity focus on the investigation of main integrated building blocks of beam-forming systems. The common feature of all the architectures illustrated in this work is the bidirectionality. This feature, along with blocks reuse, enables the realization of compact fully integrated systems. In transceivers front-end, the bidirectionally starts from the sharing of the antenna between the receiver and the transmitter. This design challenge is addressed in chapter 2, where the realization of a compact T/R antenna switch is presented. The modulation process allows the propagation of electromagnetic waves in the mmWave spectrum. Up/down converters deal with the frequency translation of modulated signal. In this field, chapter 3 presents the design of a fully bidirectional up/down converter which translates the 5G mmWave range into a fixed low GHz intermediate frequency. The up/down converter rely on an image reject architecture where 90° hybrid couplers provide the necessary quadrature phase shifting. Chapter 4 analyzes the performance degradation due to lossy components in lumped element hybrid coupler realizations. To overcome also these undesired effects, a novel calibration and compensation technique is also proposed. The effectiveness of the introduced technique is demonstrated by its implementation in the up/down converter of chapter 3. The last building block, which deals with bidirectionality, is the phase shifter whose design is illustrated in chapter 5. For this purpose, a novel technique which exploits high order passive networks to implement the phase shifting is illustrated.