Title:  Efficient, Reliable, and Secure Millimeter-wave Transmitter Systems for Joint Communication and Sensing

Committee:

Dr. Hua Wang, ECE, Chair, Advisor

Dr. Matthieu Bloch, ECE

Dr. Arijit Raychowdhury, ECE

Dr. Madhavan Swaminathan, ECE

Dr. Christoph Studer, ETH Zurich

Abstract: Phased array systems have gained attention in the recent years targeting mmWave frequencies to overcome the path loss by improving the EIRP on the TX side and SNR on the receiver side. However, phased arrays exhibit several limitations such as scan angle dependent antenna impedance variations (antenna voltage standing wave ratio (VSWR)), limited security, narrow beamwidth etc. In this dissertation, I present five different circuit/system innovations to address these limitations and enhance the performance of antenna array-based communication/sensing. First, I introduce an antenna VSWR resilient linear power amplifier (PA) supporting both series and parallel Doherty PA operations. Moreover, the amplitude and phase are reconfigured in 2-way combined PA to maintain superior performance over both halves of the smith chart. Second, I propose a multi-band role-exchange parallel Doherty-like power amplifier using a coupled line-based output network covering 26-60GHz bandwidth by switching the roles of main and aux amplifiers in a 2-way Doherty PA depending on the frequency of operation, thus supporting active load modulation over the entire operational bandwidth. Third, I present constellation decomposition array (CDA) and spatial carrier aggregation array (SCA) schemes to achieve directionally secure communication links using MIMO TX array. The desired RX in broadside receives a perfect 64QAM signal, while the undesired RXs receive distorted constellations of 64QAM thus producing a secure communication link. Next, I also introduce a Frequency Modulated Arrays (FMA) TX for full FoV localization of RXs/targets. This scheme employs a variable frequency offset between antenna elements in an array to produce distinct temporal waveforms towards RXs/targets located in different spatial directions. The received distinct waveform is used to determine the RX/target location with respect to the TX array. Last, I also present a silicon-based PTA (phase-time array) TX providing directional security and Rx localization, hence support for joint communication and sensing systems. This PTA scheme uses a complementary combination of phase shift and time delay between antenna elements in an array, thus creating spatial dispersion effect when a wideband input signal is presented to it.