Graduate Fellowship Recipients

Project topic: Investigating and proposing novel approaches in exploiting ferrite nonreciprocity to demonstrate a high-power full-duplex transceiver for 5G and future wireless systems.

Project Description: Requiring an ultra-high isolation between Tx and Rx channels at the same frequency and the same time, a full duplex transceiver has become a game changer concept that demands novel insights into redefining the current state-of-the-art in transceivers and microwave components. In our project, we investigate novel fundamental approaches to demonstrate a new class of nonreciprocal ferrite-devices that may find application in full-duplex systems. So far, we have introduced and demonstrated, for the first time, two novel ferrite-devices: ‘Nonreciprocal mode-converting waveguide (NRMCW)’ and ‘concurrent dual-mode circulator’. Exploiting these nonreciprocal devices, this project proposes methodologies to provide an ultra-high in-band isolation between Tx and Rx channels at RF-front-end to establish a full-duplex connection.

Project topic: Fully-printed, 5G-powered wireless sensing modules for perpetual IoT.

Project Description: Our era is witnessing a rapid development in the field of mm-wave and IoT technologies with a projected 50 billion IoT devices to be installed by the end of the decade. Those devices, responsible for sensing and communicating, require the use of batteries that need to be continuously recharged or replaced. Since the number of IoT devices will be massive, it is highly desirable to equip them with harvesting capabilities, and to manufacture them using low-cost and environmentally friendly processes. This work proposes the layer by layer printing of nanomaterials-based Schottky diodes, formed by the ohmic and Schottky contacts responsible for the rectification behavior, necessary for our harvesting application. In addition these unique fully-printed thin-film Schottky diodes will be used to introduce a novel sensing mechanism for fully-passive IoT systems, relying on the functionalization of the printed carbon-nanotubes films and the tunability of the Schottky barriers to enable high sensing capabilities with low-cost fabrication.

Project topic: Nonlinear modeling of GaN HEMTs for RF and microwave applications.

Project Description: The complexity of power amplifier (PA) systems for wireless communications has been escalating because of the increase in signal bandwidth and their required efficiency and linearity. Furthermore, the adoption of higher frequencies and monolithic implementations, has ascribed an essential role on nonlinear models for PA design. Unfortunately, state-of-the-art models of RF power transistors are not sufficiently accurate to design the PA based only on CAD simulations, especially for technologies such as gallium nitride high electron mobility transistors (GaN HEMT), that suffer from deep level traps. This insufficiency of representative and predictive capability of modern models is notably revealed by the nonlinear capacitance models’ internal inconsistency between the charge and energy conservation principles. The objective of this work is thus to discover the fundamental sources of these inconsistencies to then develop new equivalent-circuit compact models of GaN HEMTs that can produce better estimations of real high-frequency measured data, while maintaining high computational efficiency.

Project topic: Fourier domain mode-locked optoelectronic oscillator for multi-band chirped microwave waveform generation.

Project Description: The main objective of the proposed project is to develop a simple and cost-effective multi-band chirped microwave waveform generation scheme for radar applications with high performance. For this purpose, a multi-band Fourier domain mode-locked optoelectronic oscillator (FDML OEO) will be designed. In order to generate multi-band chirped microwave waveforms using FDML OEO, a frequency scanning multi-passband filter with a scanning speed up to tens of kHz will be developed and incorporated into the OEO cavity, which enables the Fourier domain mode locking operation when the scanning period of the multi-passband filter is synchronized with the cavity round-trip time of the OEO loop. The planned work will involve precise design and numerical analysis, and relevant experiments will also be conducted. The project aims to design and demonstrate a FDML OEO-based multi-band chirped microwave waveform generation scheme, with broad bandwidth, reconfigurability, low cost and simple structure.

Project topic: A CMOS microwave broadband adaptive dual-comb spectroscopy system with AI calibration for liquid chemical detection.

Project Description: Self-sustained nondestructive broadband dielectric spectroscopy (MBDS) systems on chip (SoC) for chemicals/biomaterials with μ-level sample volumes have attracted special attention because of a wide range of applications from chemical/biological sensing to agriculture/food safety, and drug development. However, integration of them is challenging for their high frequency operation, small area, low power consumption, required high sensitivity and low volume of the sample. The aim of this research is to investigate and demonstrate a new miniaturized fully integrated, microwave adaptive dual-comb spectroscopy (DCS) system within the 3-10 GHz frequency range in time-domain along with an on-chip system calibration, phase and time correction for highly accurate liquid chemical dielectric permittivity characterization with artificial intelligence.

Project topic: A reconfigurable 60 MHz-30 GHz PLL-less ultra-low-noise frequency synthesizer for 5G and IoT applications.

Project Description: This project presents the first attempt to implement a 30 GHz RF-MEMS oscillator via integrating lithium niobate acoustic resonators and 65 nm CMOS. This millimeter-wave (mmwave) oscillator is envisioned as the heart of a reconfigurable ultra-wide band PLL-less direct frequency synthesizer that is the end goal of this project. As a result of this study, the first voltage-controlled MEMS oscillator based on LiNbO₃ targeting mmwave will be demonstrated. Our resonator is expected to have a Q of 1000 enabling an exceptional CMOS phase noise of -74 and -134 dBc/Hz at 1 kHz and 1 MHz offsets respectively from a 30 GHz carrier while consuming only a dc power of 7mW. The direct RF synthesizer is envisioned to cover an ultra-wide range of frequencies from 60 MHz to 30 GHz via chains of low-power low-noise open loop frequency dividers. A temperature stable solution is also proposed, achieving a temperature stability of sub ppm over a temperature ranging from -20 to 60°C while consuming only micro-watts of dc power.

Project topic: Multiple-mode cavity resonator inspired waveguide circuits using emerging technologies for future communication systems.

Project Description: Nowadays, implementation of multiple-mode resonators (MMRs) in a waveguide structure is a promising solution to dramatically reduce the circuit volume and improve the frequency selectivity. Compared to single-mode resonator (SMR), besides the merits of circuit miniaturization, low-loss, and low-cost, MMRs have an inherent advantage of diverse topologies with better out-of-band signal attenuation, due to the generation of additional transmission zeros (TZs). This project seeks to take advantages of fundamental and high-order modes. By further investigating characteristics of MMRs, a series of innovative circuit components integrated with filtering functions are proposed in a range of application scenarios.  Miniaturization of waveguide circuits is implemented while maintaining the high-Q performance, and highly-integrated multiple-function in a single cavity circuit, is designed with low insertion loss.

Project topic: Advanced optimization based on surrogate modeling and space mapping techniques for computationally efficient modeling and design optimization of coupled signal and power integrity (SI-PI) analysis of high-speed interconnects and power delivery networks.

Project Description: Signal integrity-power integrity (SI-PI) co-analysis becomes essential as modern high-performance computer platforms move towards system-critical conditions. It is crucial to optimize the channel for its best performance and to find the controllable parameter enablers. This project aims to apply techniques based on surrogate modeling and space mapping, to develop an advanced optimization methodology for modeling and design of coupled signal and power integrity analysis of high-speed interconnects and power delivery networks, with high precision and low computational cost.

Project topic: A wideband, high output power amplifier from W-band and above.

Project Description: As the operation frequency of mm-W systems increases thanks to the advanced transistor processes, a wide area of applications in advanced imaging, high-resolution radar, instrumentation, and short-range communication systems are more feasible than ever. Specifically, D-band (110 – 170 GHz) is a local minimum of the atmospheric millimeter-wave absorption, therefore, showing a promising deployment of high-performance systems. One of the most critical of such systems is the power amplifier. The requirements of high efficiency, high output power, and high gain at D-band become incredibly challenging due to the cut-off frequency of the transistor and especially the losses of the passive components. In this work, we aim for a wideband, fully integrated, and high output power of 0.25 Watt covering the entire D band from 110 GHz – 170 GHz using power combining techniques in indium phosphide process.

Project topic: A low-power and low-cost monostatic beamforming radar array based on a novel 2-port transceiver chain using mutually injection-locked oscillators.

Project Description: The objective of this research is to develop a novel, low-power and low-cost 2-port monostatic beamforming radar that features compact size and only one active device in the RF front-end. In this project, although the proposed architecture uses a single antenna for Tx/Rx, no active device or circulator will be needed for Tx/Rx signal isolation. Additionally, mutual injection-locked oscillators will be used to lock the operation frequency and phase along the radar’s array, avoiding the necessity of a dedicated radio frequency PLL system. This system is aimed to enable a new generation of compact and low-cost beamforming radar suitable for massive fabrication, which opens a new gate towards the IoT deployment.

Project topic: Synthesized multi-mode frequency source with ultra-wideband and low phase noise in silicon technology for mmW and sub-THz multi-band application.

Project Description: Millimeter-wave (mmW) and sub-terahertz (sub-THz) bands are promising for high-data-rate communication, imaging radar, detection, and spectroscopy, which require high quality wideband signal. This research aims to achieve ultra-wideband and low phase noise signal source at mmW and sub-THz bands by using multi-mode oscillators and reconfigurable frequency synthesizer architecture. As the outcome of the proposed research plan, the synthesized multi-mode frequency sources for the mmW and sub-THz multi-band operation will be accomplished and verified in silicon technology.

Project topic: Effective control of electromagnetic waves through topological microwave metamaterials.

Project Description: The project is focused on experimental investigation of novel structures for effective control of electromagnetic waves (EMW) – electromagnetic topological insulators (TI) – structures which are insulators in the bulk, but on the surface conduct topologically protected states. These edge modes possess unique properties with the capability to go around the structural defects without back-scattering which makes TI a prospective technology for industry. Moreover, recent advances in physics give rise to a new class of topological systems, called high-order topological insulators (HOTIs) which provide deeper control of EMW through parts of structures, two and more dimensions lower than the system itself.  In spite of active developments of topological photonics the main focus was on studying two-dimensional TI and there is a lack of experimental realization of three-dimensional (3D) TI. The aim of the project is to fill the gap and realize experimental designs of 3D TI and HOTIs based on metamaterials in microwaves. The research has a fundamental character and creates a solid foundation for designing novel devices for different low-loss applications.