Graduate Fellowship Recipients

Project topic: Towards reconfigurable GHz wireless transceivers with galvanic body-coupled power and data transfer enabling injectable thread-like implants for minimally invasive neurostimulation.

Project Description

The effective powering of micro-scale medical implants has been one of the most critical challenges since the last decade. Traditional solutions, such as batteries and percutaneous wiring, come with significant drawbacks, including risk of infection and the need for frequent surgical interventions. While wireless power transfer methods such as inductive, capacitive, ultrasonic, optical, and RF-based techniques have made strides, they remain susceptible to misalignment and energy loss due to implant migration. Recognizing these limitations, this work adopts an efficient wireless system by utilizing locally distributed electric-field-based galvanic (differential) coupling and leveraging conductive properties of the tissue. The newly proposed system can pair with minimally invasive electrodes that anchor to internal structures like muscles and connect via flexible leads, enabling non-damaging neurostimulation of deep nerve targets without open surgery that are presently inaccessible.

Project topic: Advancement of innovative stretchable 3D printed MRI Radiofrequency coil (bio)sensor designs to aid in the early detection of breast tumors.

Project Description

Early detection of breast cancer is crucial for reducing fatality rates. However, traditional rigid MRI breast radiofrequency coils often fail to achieve the high spatial resolution needed for identifying early tumors (< 1mm in size) and assessing axillary lymph nodes. This project aims to develop a stretchable, flexible “bra-style” breast MRI coil prototype that accommodates various anatomical shapes and improves patient comfort. By optimizing the design element and material selection for these stretchable coils, we can design multi-element arrays. Preliminary research using liquid metal in these RF coils has shown improved microstructural detail. The new coil design aims to deliver robust performance across a range of sizes, ultimately enhancing image quality and reliability of breast imaging metrics.

Project topic: A highly integrated system-on-aperture (SoA) front-end using spatio-temporal modulation

Project Description

The overall noise floor is increasing for all Radio-Frequency (RF) applications, placing more stringent requirements on RF hardware to actively mitigate noise and interference. One method for improving the sensitivity of the RF Front-End (RFFE) is to adopt a co-design approach, where several functionalities are seamlessly accommodated in a single, compact module. This project aims to push the boundaries of RF co-design to integrate all the essential functionalities – frequency up-conversion, amplification, filtering, and radiation – into a stand-alone compact device. The proposed device, called System-on-Aperture (SoA), will demonstrate a fully co-designed and integrated RF Front-end, reaching fundamental limits on noise performance, interference rejection, and spectral efficiency.

Project topic: IoT-ready microwave-based smart coatings for real-time coating damage detection

Project Description

The erosive wear of coated structures poses a severe threat across industries including aviation, marine, and renewable energy. Historically, the catastrophic failures resulting from mechanical wear, and chemical degradation underscore the urgent need for preventive measures. Vishal’s work introduces a real-time, non-destructive coating inspection system integrating AI-driven microwave sensors with IoT-enabled monitoring circuitry. By detecting erosive wear in coatings, it aims to mitigate risks and enhance safety. Notably, it can distinguish between the eroding layers in multi-layer coatings and estimate wear depth and rate using neural network-based predictive analytics. This novel approach showcases practical potential for addressing real-world challenges in coating wear applications.

Project topic: Fully 3D printed dual-port rectenna for wearable SWIPT applications exploiting multi-sine excitation

Project Description

This project aims at taking advantage of 3D printing technology in terms of ease of use, cost-effectiveness and design degrees of freedom for the fabrication of a wearable, fully 3D printed, completely passive radiofrequency identification (RFID) tag for indoor localization and simultaneous wireless information and power transmission (SWIPT). A dual-mode rectenna is able to harvest power from a multi-sine excitation, and to backscatter a passively generated and modulated quasi-ultrawideband (UWB) signal communicating inertial information of the subject wearing the tag, collected by a sensor.

Project topic: High-Angular-Resolution Sub-THz Imaging System with Antenna-in-Package (AiP) Technology

Project Description

This project proposes a sub-THz 4D imaging system that decouples the designs of active circuits and large passive antenna array, which naturally circumvents the challenges of high circuit complexities, electronic density, and computation power, in traditional phased/MIMO array systems. Antenna in package (AiP) technology, which has much higher radiation efficiency than the on-chip solutions, is implemented for both the reflectarray and the radar transceivers. Digital circuits and memories are integrated on massive tiny chiplets and mounted on multiple package modules, in order to reduce the total silicon area. A full-duplex technique is further applied to combine the two sub-systems. Meanwhile, a multi-transceiver (multi-static) topology is designed for lower system profile, higher total radiated power and better flexibility of signal processing. The proposed 250GHz 4D radar imaging system is expected to have <1° angular resolution, with >100m of detection range.

Project topic:

Multichannel, multifunction, and multiport interferometric waveguide transmitter and receiver systems for THz communication, sensing, and imaging applications

Project Description

To develop the terahertz (THz) multifunctional, multistandard, and multimode wireless systems, many radio frequency (RF) challenges about the hardware circuits and transceiver architectures should be addressed. In fact, these significant challenges in building THz hardware and systems have turned the THz spectrum into the widely acknowledged last frontier. Conventionally, these challenges are solved according to the technologies used at microwave frequencies adapted to higher frequencies. However, the effects of propagation losses, parasitics, and mechanical limitations are significant, making them unacceptable in the THz frequency range. Therefore, it is imperative to develop a highly effective and low-power consumption wireless platform that can support the development of various THz applications. In this research, several multiport architectures based on the interferometric technology are proposed and developed with minimum possible power consumption while maintaining excellent performance. The main research goals are to propose, explore, and develop highly original interferometric transmitters and receivers for future wireless communication, sensing, and imaging systems.

Project topic: Design of flexible MIMO radar sensors to improve angle estimation

Project Description

Radar based sensors are ubiquitously applied in an uncountable number of different applications. In order to enhance the systems, Gabsteigers research aims to further investigate radar-based machine learning. The basis of the work is a state-of-the-art fast chirp frequency modulated continuous wave (FMCW) 60 GHz multiple in multiple out (MIMO) radar. In this system, the angular resolution will be improved compared to state-of-the-art radar systems. To achieve this, a special waveguide antenna design with beam squinting capability is proposed. Since radar data processing is not possible with the usual signal processing for a beam squinting antenna, machine learning is an essential component of this research. In this way, with the help of machine learning, it is easier to identify objects within one field of view, even when they are closely spaced.

Project topic: Research on multi-mode outphasing power amplifier for multi-band application

Project Description

To process the wideband modulated signals more efficiently, not only saturation but also back-off drain efficiencies (DEs) are highly expected by a broadband power amplifier (PA) to reduce the power consumption in wireless communication systems. Therefore, PA architectures maintaining high back-off DE are widely developed and investigated these years, such as Outphasing PA (OPA), Doherty PA (DPA), and load-modulated balanced amplifier (LMBA). Compared to the DPA and LMBA, OPA offers a better efficiency profile in theory. However, the frequency coverage of the OPA should be improved. Therefore, it is interesting to research on multi-band OPAs so as to cover a large frequency range. This work will focus on the theory and design of multi-band OPAs based on multiple operation modes.

Project topic: Design and analysis of spatio-temporal modulation based nonreciprocal filters, antennas, and metasurfaces using FDTD

Project Description

Non-magnetic non-reciprocal electronic devices are advancing rapidly, leveraging spatiotemporal modulation techniques for compact and efficient designs. Our project focuses on designing and analyzing non-reciprocal filters, antennas, and metasurfaces, disrupting reciprocity between transmission and reception. Through tailored Finite-difference Time-domain (FDTD) simulations, we aim to enhance modeling capabilities for these devices, offering practical solutions for communication, radar technology, and sensing challenges.

Project topic: Broadband energy-efficient silicon-based terahertz circuits and systems

Project Description

To meet the ever-growing demand for wireless services in the B5G/6G era, it is essential to push wireless communication and sensing systems toward the terahertz (THz) band. With the rapid advance of silicon-based semiconductor technology in recent years, it has become possible to implement THz circuits and systems with low cost and high integration. However, due to the low breakdown voltage, limited f_max of silicon-based transistors, and high loss of on-chip passive devices, it still remains challenging to implement high-performance silicon-based THz circuits and systems with wide bandwidth and high efficiency, especially in the aspects of signal generation, power amplification, and system integration. Aiming at the above challenges, this project plans to explore key techniques to improve the comprehensive performances of THz silicon-based circuits and propose practical solutions for realizing broadband energy-efficient silicon-based THz systems.

Project topic: High Linearity Phased Array Receiver System for 5G/6G Application

Project Description

As the new phase of 5G/6G moves towards the frequency band of 6-18GHz, the communication systems are expected to support multiple frequency bands with a single unit. In this work, a 6-18GHz high linearity beamformer receiver chip will be tested and used to design a 16-by-1 demonstration phased array. The RF beamforming system contains a Vivaldi-based wideband antenna array, 2 beamformer chips, and Wilkinson combiners. The wideband receiver system gain, G/T, receiver pattern, and power consumption, will be measured to evaluate the system performance. The modulation measurement will demonstrate the 5G communication system performance with the presence of interference. This work will be the first compact wideband system that supports future 5G/6G band multi-standard micro base station applications.

Project topic: Microwave heating and dielectric characterization for flow chemistry

Project Description

The chemical industry lags in the transition to greener practices due to old-fashioned and inefficient reactors. To overcome this, microwaves are increasingly being used to intensify organic synthesis reactions and improve their outcome in terms of product purity. However, these improvements were mostly demonstrated on the scale of mL’s using commercial equipment that relies on high-power 2.45 GHz reactors. Even though the advantages of microwave-based heating have been clearly demonstrated, we believe that this is merely the tip of the iceberg, and further significant improvements can be achieved by 1) moving to flow-based systems, 2) using optimized signal waveforms (power and frequency) for a given reaction, 3) using dielectric sensors for in-situ monitoring. By truly exploring the entire design space available for advanced microwave-based thermal control systems on the microscale, we aim to automate chemical reactions and their optimization. Finally, transitioning to resonant cavities will allow us to scale flow devices that can generate compound libraries with high throughput in a fast and energy-efficient manner.

Project topic: Physics-informed neural networks for time-domain electromagnetic and multiphysics modeling

Project Description

Physics-informed neural networks (PINNs) combine the power of machine learning algorithms with computational physics to accurately model the underlying physical systems with reduced or even no reference data. While PINNs have gained popularity in computational electromagnetics, their practical applicability has been limited to simplified toy cases. This project aims to advance PINNs for practical microwave simulations by delving into important areas such as performance benchmarking and the integration of complex media and open boundaries into PINN-based electromagnetic solvers. Our research will explore optimal neural network architectures and efficient training strategies to develop fast and accurate solvers for microwave/RF device modeling and uncertainty quantification. Furthermore, we intend to accelerate multiphysics modeling by coupling PINN solvers with other computational techniques, aiming to offer an efficient alternative for large-scale 3D electromagnetic and multiphysics simulations. This work is expected to lead to significant improvements in the capabilities of PINN solvers for realistic electromagnetic and multiphysics applications.

Project topic:  Theories and techniques for a real-time monitoring microwave ablation system

Project Description

Microwave ablation (MWA) is considered one of the most promising tumor treatment techniques due to its minimal invasion. However, it is still challenging to accurately control and determine the boundary of the ablation zone during the tumor treatment. Considering that temperature difference can lead to obvious permittivity difference, which is the foundation of a microwave imaging system, a time-domain real-time monitoring system is planned to be developed. For preliminary experiments, a simple imaging platform is built, and a series of focused images have been obtained. In order to increase the measurement accuracy and speed, multiple antennas are required to improve the proposed system, to provide a large amount of observation information from different angles without using mechanical rotation. In addition, a switch matrix and an ultra-wideband sampling unit are planned to be developed, and then a great of focus will be on the improvement of real-time imaging algorithms.

Project topic: Linearization angle widened digital predistortion for multi-user MIMO systems

Project Description

Multiuser multiple-input multiple-output (MU-MIMO) stands out as a significant enhancement, optimizing transmitter capacity utilization by enabling simultaneous communication with multiple users. Power amplifiers (PAs),

being the most power-intensive components in transmitters, typically operate in high-efficiency mode, resulting in nonlinear distortion that degrades communication quality.

This research is to develop a digital predistortion (DPD) method for MU-MIMO that widens the linearization angle. Firstly, we will derive a model from the magnitude-selective affine (MSA) functions to address distortions arising from multiple user data streams and employ a cross terms shared architecture to reduce the operation complexity of the model. Secondly, we will propose a linearization angle widened DPD to further enhance the total radiated power (TRP)–based adjacent channel leakage ratio (ACLR).

Project topic: Pulsed low-noise amplifiers for quantum information systems

Project Description

In the rapidly expanding of quantum computing, integrating more qubits requires lower power consumption in readout amplifiers, making the DC power of Low Noise Amplifiers (LNAs) a critical design constraint. This research proposes a novel approach to significantly reduce the power consumption of LNAs used in superconducting qubit readout at 4 K. By implementing pulsed operation of qubit readout, the project aims to decrease power consumption by two orders of magnitude without sacrificing noise performance. The methodology includes developing a technique for nanosecond-resolution transient noise characterizing under cryogenic conditions, and designing LNAs with enhanced recovery time. The anticipated result is a 100-fold reduction in DC power consumption while maintaining a noise temperature below 2 K, thereby overcoming a crucial hurdle in the scalability of superconducting quantum qubits for future quantum computing advancements.

Project topic: Non-invasive real-time analysis of electroporation phenomenon of individual cells with microwave dielectric spectroscopy

Project Description

Electroporation, a method allowing transient permeabilization of plasma cell membranes through the controlled application of electrical pulses, raises new hopes in the medical field with the fight against cancer. Combining electroporation with the administration of anticancer agents enables the targeted and efficient delivery of the latter, hence enhancing their cytotoxicity. Early prediction of cellular response to electrochemical treatments could help optimize electrical parameters and chemical concentrations, aiming towards personalized medicine. Microwave dielectric spectroscopy offers an attractive and innovative approach to characterize cells subjected to various treatments, non-destructively, non-invasively, in real-time, and at the single-cell level. This project aims at dielectrically analyzing the electroporation phenomenon on individual cells submitted to different stimulated electrical conditions. It includes the development of a dedicated instrumentation, which combines electrical stimulation applied at the single cell level, accurate and reproducible microwave sensing and fluorescent-based observation to correlate both biological modifications and dielectric responses of cells. Its validation and application to different cell models are under progress.

Project topic: Spectrum-Efficient multi-target vital sign monitoring using metamaterial-integrated space-time-coding transmitting array

Project Description

As wireless health monitoring technology advances, the need for monitoring the health of multiple individuals becomes increasingly significant, particularly in overcrowded and resource-limited clinic situations. However, the leverage of the mechanical rotors or the phase shifters increases the hardware complexity and cost of the radar system. Meanwhile, the utilization of metamaterial leaky wave antennas occupies a significant portion of the frequency spectrum, contributing to spectrum congestion in the 5G communication environment. In response to these challenges, we introduce the space-time-coding transmitting array for direct antenna modulation to detect the vital signs of multi-targets within the significantly narrow frequency range. By leveraging the steering harmonics of the time-modulated transmitting array, we can achieve concurrent health monitoring of multiple targets while satisfying the spectrum coexistence in the era of continued 5G evolution.

Project topic: Development and Integration of a General-Purpose Automatic Tuning and Matching Circuit for Stretchable Coils

Project Description

Recent research in RF hardware for MRI involves utilizing stretchable and flexible coils, which provide adaptability to various anatomical structures, potentially enhancing imaging quality and patient comfort. However, these coils suffer from frequency shifts from changing impedance during stretch, compression, and bending. Despite prior research exploring potential solutions to this issue, a stable, general-purpose automatic tuning and matching system for these coils remains elusive, limiting their clinical viability. This work aims to bridge this gap by innovating and evaluating an automatic tuning system to retune the resonance frequency across all stretchable coils. The work will shape research on conformable antennas and devices, extending its impact beyond MRI to various wearable devices.

Project topic: Development of a standalone RF sensor system for humanitarian applications

Project Description

RF sensors are presently being used for a number of industrial, biomedical and humanitarian applications due to their several advantages such as ease of fabrication, low cost, non-invasive approach, etc. However, one of the major bottlenecks limiting their usage for various humanitarian applications is their low sensitivity, and limited portability due to the requirement of a costly measuring instrument such as the Network Analyzer. This project primarily aims to develop a Standalone RF Sensor System comprising a high sensitivity planar RF sensor, the RF source, and a detector, primarily for humanitarian applications such as detection of adulteration in various edible food products. The overall work would primarily involve 1) design and development of a highly sensitive RF planar sensor for various biomedical and humanitarian applications; and 2) integration of the sensor with a low cost  RF system, to realize a  portable, lightweight, standalone RF sensor system for testing of various edible and bio-grade fluids.

Project topic: Wideband self-adaptive fast-locking frequency synthesizer with low phase noise in CMOS technology for multi-band wireless applications

Project Description

Multiple-band operations for the 5G/6G wireless communication require frequency synthesizer with wide tuning range and low phase noise. At the same time, the short locking time is an important design requirement, especially for future multiple users requiring big data or fast vehicles traveling among cities and towns. This research aims to achieve the frequency synthesizer with the merits of the wide output frequency range, low phase noise, and self-adaptive short locking time. As the outcome of proposed research plan, the wideband self-adaptive fast-locking frequency synthesizer with low phase noise will be implemented and verified using CMOS technology for multi-band wireless systems.

Project topic: Solid-state plasma switches for reconfigurable high-power RF electronics

Project Description

Conventional RF switching technologies struggle to simultaneously achieve high-power handling, low loss, high isolation, broadband operation, quick reconfiguration, and high linearity, which are desirable for many applications, including communications, radar, and sensors. Moreover, they require electrical bias networks, which degrade performance and, in many cases, inhibit wideband applications, including dc operation. On the other hand, plasma (photoconductive) switches use an optical bias to generate free charge carriers. Recently these switches have begun to not only rival conventional technologies in terms of performance metrics such as switching speeds and loss but have exceeded what is possible in terms of power handling. This work details the strides made in placing solid-state plasma technologies at the forefront of advanced, high-power switching applications including a novel high-power tuner and an absorptive/reflective SPDT switch.

Project topic: On-demand energy-saving multi-metric digital predistortion for future wireless systems

Project Description

To exploit the limited communication resources, the wireless system will operate in a flexible manner in which multi-metric linearity requirements could be posed.  The nonlinearity in different frequency regions is required to be suppressed to different levels, and the requirements may also change from time to time subject to channel condition and collaborative scenario.  My project aims at developing digital predistortion (DPD) model extraction algorithms and model topology adaptation strategies for multi-metric linearity requirements in different frequency regions, so that the DPD system can acknowledge which model terms should be switched on and which ones should be kept dormant for different multi-metric demands, with the least power consumed for DPD related digital circuits.

Project topic: Smith-purcell terahertz radiation from a beam of particles moving above a grating of graphene-covered dielectric rods

Project Description

We plan to study the terahertz and infrared range diffraction radiation (DR) of a modulated beam of electrons flowing near the grating of graphene-covered dielectric nanowires. In our analysis, we assume that the beam velocity is fixed and the graphene cover can be characterized with the aid of the Kubo formalism and resistive-type boundary conditions. Then, using the separation of variables in the local coordinates and the addition theorems for the cylindrical functions to account for the wire shape and location we transform the diffraction radiation problem to a Fredholm second-kind matrix equation. This yields a meshless numerical code, which has a mathematically guaranteed convergence, and allows us to compute the scattering and absorption characteristics and the far and near field patterns with controlled accuracy. This work can be useful in the design of novel sources of terahertz waves and of dielectric laser accelerators.

Project topic: Hybrid circuits-antennas integration for future wireless systems

Project Description

In millimeter-wave (mmW) and terahertz (THz) applications, the transmission behaviors of circuit structures and component parts such as radiation and leakage losses are critical for the overall performance of associated system in question. It is imperative to develop a low-loss interconnect and transmission technique that should be used for the development of building circuit blocks. In this project, a hybrid metallo-dielectric waveguide architecture is proposed and studied with special interest in maximum possible loss reduction while maintaining an excellent degree of freedom in circuit developments. The scheme is made of mixed dielectric waveguide (DW) and non-radiative dielectric (NRD) waveguide, which are respectively deployed for the design of specific building parts in consideration of the two waveguide properties. The main research goals are to propose, study and explore highly original wireless transceiver architectures and technologies with the enabling integration platforms of wireless functions and hardware structures.

Project topic: A heterogeneous mode-converting power radiator for broadband sub-THz applications

Project Description

The growing interest in the data intensive applications has led to the development of mm-wave integrated circuits at frequencies above 100 GHz. However, there are various challenges inherently associated with the conventional semiconductor devices at these frequencies such as insufficient power generation, excessive passive loss, low amplification gain, and the increased path loss of the radiated signal. This requires a power amplifier (PA) with high gain and high output power and a directive antenna with efficient radiation for the transmitter. Furthermore, to exploit the true potential of mm-wave band, broadband performance is required from both the PA and antenna. In this proposal, we aim to design a novel broadband PA using 8×1 power combiner, a broadband dual-polarized antenna, and a low-insertion-loss and broadband multi-layer interface circuitry between the chip and flexible printed circuit (FPC) board that efficiently couples the electromagnetic field from the PA chip to antenna.

Project topic: High accuracy wireless distributed coherent array synchronization

Project Description

Wireless distributed coherent arrays at millimeter-wave frequencies and beyond will become an enabling technology, soon facilitating systems from on-orbit long baseline interferometers for astronomical observations, to collaborative automated vehicle radar arrays to enhance angular resolution and spatial diversity. While the applications for these arrays are many, there is still significant work required to synchronize the nodes in the array to provide coherent time, frequency, and phase aligned operation at millimeter-wave carrier frequencies and multi-GHz bandwidths. This work will focus on the design and implementation of a system to wirelessly coordinate distributed platforms to align frequency, time, and phase, through high accuracy time transfer techniques.

Faculty Advisor: Prof. Robert Weigel

Project topic: On-chip baseband signal generation for digital millimeter-wave noise radar systems in 22 nm FDSOI

Project Description

State-of-the-art CMOS technology enables radar systems at mm-wave frequencies, which provide increased, ultra-wide bandwidth. Phase-modulated continuous-wave (PMCW) radar represents an alternative to the widely used frequency-modulated continuous-wave (FMCW) radar, in which a pseudo-random binary sequence (PRBS) is modulated onto a carrier frequency. This sequence is used for broadband frequency utilization and separation between channels in MIMO or joint radar-communication (RadCom) systems. Since the range resolution depends on the data rate of the PRBS, and must therefore be as high as possible. We will investigate and realize different PRBS generators for an integrated 140 GHz PMCW radar transmitter realized on a 22 nm fully-depleted silicon on insulator (FDSOI) technology. The transmitter is used in a radar system for gesture recognition enabling non-contact human-machine interaction, e.g., when operating smartphones or entertainment systems in cars.

Faculty Advisor: Prof. Tomás Palacios

Project topic: Heterogeneous integration of GaN and Si for MMICs above 300 GHz, 6G applications and beyond

Project Description

The future of Gallium Nitride (GaN) radio frequency (RF) circuit technology is at the intersection of material synthesis, device modelling, and circuit design. Currently, these are three separate fields with little-to-no communication between them, resulting in critical limitations to today’s technology. There is an urgent need for these fields to collaborate, cross-pollinate, and intersect to modernize and advance innovation for the next generation of RF circuits. To design the most efficient RF and mmWave circuits, we must embrace the design technology co-optimization (DTCO) approach, that combines new GaN-based transistors with engineered linearity, novel heterogeneous integration with state-of-the-art Silicon (Si) control circuits, and advanced physics-based modeling. This project sets the foundation of the next generation of RF and mixed signal circuits for applications such as 6G and hypersonic environments.

Project topic: High signal integrity transmission lines enabled with thin films and design techniques

Project Description

The development of modern wireless communication systems drives the radio devices toward the trend of smaller size, higher speed and frequency. Accordingly, crosstalk becomes one of the dominant limiting factors in microwave and mmwave communication systems. In this research, high signal integrity transmission lines enabled with thin films and design techniques are proposed for far-end crosstalk (FEXT) mitigation. First, a novel tabbed routing transmission line with multiple trapezoidal tabs on both sides of the signal trace are proposed for the reduced FEXT. Methods to further reduce FEXT, including transmission line structures with non-uniform signal conductor thickness and integration of high permittivity dielectric thin film and high permeability magnetic thin films, are investigated. Moreover, the proposed high signal integrity transmission lines are comprehensively studied by theoretical modelling. The equivalent circuit model is established and the closed-form formulas for calculating capacitance and inductance values will be derived. The proposed concepts in this research project have a great potential in modern microwave systems.

Project topic: Energy-efficient, wideband, and linear power amplifier theory and architectures for next-generation wireless transmitters

Project Description

The increasing demand for mobile data traffic creates new challenges for next-generation communication systems, which require higher-order modulation formats and produce signals with a large peak-to-average power ratio (PAPR). RF power amplifiers (PAs) are critical building blocks in the communications system, including radio base stations, mobile handsets, and wireless point-to-point links, governing energy efficiency, bandwidth, and linearity performance. This project investigates and analyzes the theoretical limits and design tradeoffs of state-of-the-art high-efficiency PA architectures, while developing and exploring new operating modes and innovative PA architectures. The research goal is to propose new and innovative PA solutions for practical GaN and silicon PA prototypes designed for various frequency bands in beyond-5G/6G wireless communication systems.

Project topic: Cancerous or not? Microwave Judges! Microwave systems for dielectric characterization and actuation at the single-cell level in life sciences

Project Description

A promising way to fight cancer in the early stages, among other diseases, is through information carried by single cells and extracellular vehicles (EVs) released by them. However, extracting this information often depends on the availability of biomarkers and their matching bioreceptors. Thus, label-free cell and EV analysis is critical. Collecting the EVs, on the other hand, is challenging and requires a large number of cells to release the EVs. To circumvent this necessity, this research will contribute to exploring in the application of microwave dielectric sensing and actuation, combined with microfluidics as a platform capable of distinction and separation of single cells and analyzing EVs in a label-free manner. This platform acquires multi-band passive microwave sensing by using resonant planar microwave sensors and thermal actuation to collect the cells that release EVs for biomedical analysis.

Project topic: Doppler cardiogram detection based on millimeter wave radar and its biomedical applications

Project Description

Non-contact radar sensing technology can obtain human vital signs by measuring the displacement generated by the heartbeat and respiration on the chest wall. High-sensitivity millimeter-wave radar systems can capture fine cardiac volume change trajectory and obtain the “Doppler Cardiogram (DCG)”, which has been validated to have correspondence with electrocardiogram (ECG). This project will focus on the DCG detection in clinical environment, investigate and analyze the feasibility of cardiac time intervals measurement, based on which diagnosis of cardiac diseases and sleeping stages classification will be achieved. Custom-designed millimeter-wave radar systems and novel signal processing techniques will be developed to realize accurate detection of DCGs in the presence of respiration. Moreover, accurate deep-learning-based diseases detection and sleep staging models will be exploited for advanced non-contact smart healthcare.

Project Topic: Multi-function receiver array with multiple interferences suppression in CMOS technology for mm-wave applications

Project Description

Future multi-standard wireless provides high data-rates using the wideband millimeter-wave spectrum. Meanwhile, modern and future wireless applications (e.g., 5G, vehicles, and intelligent manufacturing) occupy the spectrum and make the wideband wireless systems operate in a complicated EM environment, where multiple signals  will be received in practical applications. Meanwhile, the receiving signals along with the LO signal will generate unpredictable intermodulation. Those receiving signals and intermodulation products located at the RX channel (in RF or IF domain) will cause a significant performance degeneration in RX systems. This research aims to achieve a multi-function mm-wave receiver array capable of suppressing multiple interference and can be reconfigured to meet the requirement in different applications. As the outcome of proposed research plan, the multi-function RX array will be implemented and verify for mm-wave wireless systems.

Project Topic: Energy efficient, linear, and wideband mm-wave transceiver front-end for next-generation wireless communication systems

Project Description:

To address the highly growing data-rate demand, it is envisioned that mm-Wave will be extensively employed in 5G-and-beyond communication system for increases of channel capacity and broader applicable spectra. Viable mm-Wave Tx/PA front-end solutions are required to support multi-Gb/s spectrum-efficiency modulated signals. Corresponding large PAPR cause that Tx/PA must demonstrate exceptional linearity to maintain signal fidelity and exceptional efficiency at PBO. Similarly, mm-Wave RX front-end solutions should achieve high sensitivity and linearity while maintaining a wide bandwidth to proceed high speed signals. Our research plan aims to exploit new circuit architectures and techniques to address the mm-Wave TRx design challenges. We propose a Continuous Mode Coupler Balun Doherty PA covering 26-60GHz and 35-100 GHz with high peak PAE and substantial PBO efficiency enhancement. On Rx side, a broadband dynamic 2-D full FoV MIMO RX array is proposed to support full-space signal beam-forming/-tracking and perform rapid automatic spatial filtering on unknown blockers with µs low latency over full FoV.

Project Topic: Terahertz Schottky diode harmonic mixers

Project Description

Terahertz heterodyne receivers are indispensable tools for detecting molecular lines and, therefore, essential in planetary and atmosphere sciences. A key component for high-resolution spectroscopy is a stable local oscillator (LO) source. Over the past decade, quantum-cascade lasers (QCL) have shown a steady performance improvement, thereby paving the way for the realization of compact THz heterodyne receivers. However, QCLs are susceptible to frequency drifts and instabilities due to cryocooler vibrations and temperature fluctuations. Hence it is crucial to frequency stabilize the QCLs. Schottky diode mixers have a fast response time, compact, and are ideal for QCL phase locking applications.

This project aims to design Schottky diode harmonic mixers working at 3.5 THz and 4.7 THz for phase locking of QCLs, aiming for future space/air-borne missions.

Faculty Advisor: Prof. Ruonan Han

Project Topic: Towards battery-less THz transceivers with physical layer security for ultra-miniaturized platforms

Project Description

Integrated electronics is filling up the Terahertz (THz) gap for the last two decades but battery-less THz transceivers (TRx) have not been realized due to their stringent challenges. There is also a growing demand for ultra-low power mm-size TRx in supply chain management, authentication, micro-robotics, etc. and with the proliferation of THz-TRx, the security of wireless links is another emerging issue. In this project, novel approaches are proposed to realize physically secure and energy harvesting based THz-TRx. Specifically, a transformative physical-layer security scheme using the helical distribution of wavefront phase (namely orbital-angular-momentum) is employed for secure transmission. Furthermore, the circuit architectures for highly-efficient CMOS THz energy harvesters are explored for wirelessly powering the TRx.

Project Topic: Highly efficient mmWave based far-field wireless power transfer system using metaconductors and metamaterials

Project Description

This project proposes a highly energy-efficient mmWave-based far-field wireless power transfer (WPT) system using metaconductors (MCs) and metamaterials (MTMs). In order to achieve high end-to-end efficiency of the far-field WPT system in mmWave, the following two approaches are proposed. First, the usage of multi-layer non-ferromagnetic/ferromagnetic conductors (MCs) as eddy current canceling conductors is proposed to implement all the interconnects and passive components including transmitter (Tx) and receiver (Rx) antennas, feeding lines, and rectifier lines. Based on the preliminary studies, the proposed MC based Tx and Rx array antennas are expected to show at least 6 dB gain enhancement each compared with Cu based counterparts. Second, a beam focusing MTM lens is introduced to focus and align the electromagnetic fields for high gain Tx and Rx antennas. It is highly expected that the proposed WPT system will open new possibilities for practical WPT applications with enhanced efficiency.

Project Topic: Reconfigurable integrated devices for compact terahertz systems

Project Description

The terahertz band is commonly used to refer to electromagnetic radiation with frequency ranging from 100 GHz to 10 THz. In recent years there has been accelerating interest in using terahertz technologies for high speed, beyond 5G, wireless communications. Currently, integrated circuits built from all-silicon dielectric waveguides are a promising avenue for achieving these goals. However, the properties of dielectric waveguides mandate that these systems must be relatively large to avoid cross-channel interference and are inherently passive following fabrication. This project seeks to explore a variety of techniques to reduce the size and increase the flexibility of dielectric waveguides to enhance the performance and accelerate further development.

Project Topic: A frequency agnostic beamforming system with non-uniform array geometry and wideband transmitter for mm-wave wireless links

Project Description

The evolving spectral allocations in the mm-wave bands across 24-100 GHz necessitate future front-ends to address multiple bands spread across the spectrum.  Current phased array systems based on uniform linear arrays are fundamentally incapable of operating across a wide range of frequencies extending beyond an octave without grating lobes. In addition, the broadband specification poses significant challenges for the power amplifiers (PAs): a design demanding GHz channel bandwidths across multiple bands over a 3:1 mm-Wave bandwidth, while maintaining high linearity and efficiency. To this end, my research aims at: 1. Fundamental design methodologies aiming toward a non-uniform array geometry, capable of operating across a broad range of frequencies (>3:1).  2. Novel transmitter architectures using mm-wave harmonic engineering, stacked common base PA cells and Non-Foster impedance tuning to enable high PA efficiency and linearity across this wide frequency range. Such a frequency agnostic beamforming array can fundamentally redefine dynamics of the next generation of concurrent multi-band wireless networks.

Project Topic: Terahertz on-wafer metrology for future space applications

Project Description

Many ESA missions utilize satellite-mounted radiometers that observe various aspects of the Earth and its atmosphere, thus high-fidelity on-wafer measurements are essential for the fabrication of high-quality integrated circuits operated in free space.  The focus of this research is to develop measurement techniques for device qualification, in particular on-wafer and quasi-optical measurements in the WR-2.2 (325 – 500 GHz) band. To address the barriers facing the frequency scaling of standard RF measurement techniques, on-wafer calibration techniques for the WR-2.2 band will be developed, including new mathematical approaches for error formalisms,  simulation and fabrication of on-wafer calibration standards for further tests using the terahertz probe station.

Project Topic: Broadband digital predistortion of efficient multiple-input RF power amplifiers exploiting optimization and machine learning techniques

Project Description

Digital predistortion (DPD) is one of the most widely used techniques to compensate for nonlinear dynamic effects in RF transmitters. However, devising effective DPD strategies in the context of multi-input PAs is not straightforward. Moreover, the flexible control of multiple inputs adds degrees of freedom that could enable better linearity/efficiency trade-offs. The project aims at investigating a new approach to DPD coefficients learning, in which they are jointly identified by a multi-objective optimization (MOO) framework maximizing a given set of contrasting figures of merit (e.g., linearity, efficiency, RF output power, etc.). To avoid the high number of measurements that would be needed to run a MOO learning procedure, the proposed algorithm is based on a surrogate model of the PA, which can be identified and refined during the learning procedure. The project targets the experimental validation of the framework on a Dual-input Doherty PA.

Project Topic: Simultaneous two-dimensional tuning using non-linear transmission lines

Project Description

Picosecond pulse generation, compression, and transmission are very desirable in ultra-fast electronics, geophysical exploration, discharge plasma, biological electromagnetics, and future oscilloscopes. This research aims to investigate theoretical and experimental development in non-linear transmission line (NLTL) along with the demonstration of simultaneous rise and fall time compression. The two-dimensional tuning concept including electric and magnetic tuning is explored in NLTL and new innovative schemes are proposed in this regard. These pulse generators are then utilized in a practical system and the corresponding received waveform response is studied. The transceiver effect on pulse characteristics is deeply studied and detailed ringing is analyzed. A technique will be explored as well to mitigate the ringing instead of using a conventional late time ringing mitigation technique. Gaussian and higher derivatives of Gaussian pulses are also developed and their capability to maintain their shape after the transmission is also explored.

Project Topic: Highly efficient integrated THz pulse and CW radiators and receivers for broadband sensing, imaging, and Communication applications

Project Description

With the emergence of new IOT and mobile applications, there has been an ever-increasing demand for high-data rate wireless communication and high-resolution sensing. Sub-Terahertz band offers a wide unlicensed bandwidth that plays a critical role in the realization of the aforementioned applications. Considering that current commercial THz systems are costly and bulky, developing these systems in standard silicon technologies is vital to lower the cost. In this research, we propose a novel technique based on PIN diode reverse recovery to improve the power, bandwidth, and efficiency of the generated THz waves in silicon-based processes. Using the concept of reverse recovery, PIN-diode-based pulse and Continuous Wave (CW) radiators and receivers are designed that are utilized for spectroscopy, Doppler radar, and multi-Gbps THz communication.

Project Topic: Towards beamsteering microwave topologies for passive sensing applications.

Project Description

The goal of this research is to investigate, develop, and test novel beamforming microwave topologies for passive sensing applications that leverage current and next generation Wi-Fi, Bluetooth, and wireless power transfer infrastructures to make best use of radio-frequency (RF) radiations, spectrum, and wireless networks for ubiquitous smart home, health care, and smart living. Most of the reported passive sensing systems that leverage Wi-Fi signals rely on complicated architectures for signal acquisition and processing. In this project, a passive sensing topology based on injection-locking technology will be developed to achieve robust detection of small amplitude motion (e.g., noncontact vital sign monitoring). On the other hand, three other low complexity, low cost, and compact microwave systems with no on-board RF oscillator will be designed for the remote recognition of large amplitude movements such as hand gestures, physical activities, walking and falling.

Project Topic: Optical diffraction and delectrophoretic analysis of cells using cytometer

Project Description

This project will examine the light-scattering properties of cells through a combination of theoretical simulations and experiments. A microfluidic channel will be used to measure the dielectric and optical properties of cells. MIE theory technique will be used to compute intensity of scattering pattern of cells. The pattern will be used to generate optical data. Fluid dynamic simulation will be employed to trace particle trajectory in the channel. The height of particle in the channel after electrodes can change based on its dielectric properties, since the particle experiences dielectrophoresis force in the microfluidic channel (nDEP or pDEP). The differential velocity of the incoming particle and outgoing particle can be used to define the height of the particle after electrodes in the channel or vice versa. Based on these changes, dielectric properties of the cells’ compartments can be determined.

Project Topic: Design and implementation of energy-efficient millimeter-wave transmitter architecture at 61 GHz in 22FDSOI CMOS process for sub-mm localization of body-worn electromyography (EMG) sensor nodes

Project Description

In the field of medicine and psychology, accurate analysis of physiological, behavioral states and body functions is often required for efficient patient diagnosis and therapy. This requires both the muscle activity information and its precise location source. In this project, a 61 GHz mm-wave transmitter chip is to be designed in 22nm FDSOI (Fully Depleted Silicon-On-Insulator) CMOS (complementary metal-oxide semiconductor) process for extremely energy-efficient & localizable, non-invasive biomedical wireless EMG transponder. This facilitates a novel approach towards acquiring real-time surface EMG data while simultaneously achieving high-precision sub-mm accurate localization of the source muscle. The research task focuses primarily on the investigation, design, verification & characterization of mixed-signal energy-efficient mm-wave front end and base-band circuits for the transmitter to meet the low-power and carrier stability requirements of the transponder. In a further step, the transmitter chip is to be integrated into an EMG sensor platform, which will be evaluated in test series on probands, e.g., in the face or on legs, to analyze facial expressions and gait.

Project Topic: A 60GHz > 50Gbps phased-array transceiver chipset using harmonic reject/image reject (HR/IR) mixer-based carrier aggregation.

Project Description:

The massive unlicensed bandwidth across mm-wave frequencies allows us to design systems with high data rate capabilities for short-range radios and cellular backhaul applications. In this work, we explore carrier aggregation in mm-wave frequencies to enable extreme high data-rate communication links. For TX/RX systems with high aggregate bandwidth, the need for high speed, power-hungry ADCs/DACs at baseband increases the system cost while degrading the overall system efficiency. To tackle these problems, we exploit harmonic rejection mixing and image reject mixing to enable a power-efficient carrier aggregation architecture that reduces the sampling rate requirement of the ADC/DAC by 4X, and consequently, can reduce the cost and power consumption significantly.

Project Topic: Millimeter-wave wireless power transfer system for wearable devices.

Project Description:

The project aims to design an end-to-end wireless power transfer system in the mm-wave range, to be deployed for wearable devices. Focusing techniques for energy transfer in both the near- and far- field of the source will be investigated with the manifold goal of optimizing the overall system efficiency, localizing the energy transfer in real-time and minimizing the wasted energy (and thus EM pollution) in unwanted locations. The approach will be based on co-simulation techniques (full-wave and circuit-level nonlinear design) in order to provide a reliable numerical prediction of the entire mm-wave WPT link. The solutions proposed will be compared with more traditional low-frequency solutions for both the near- and far- field powering in terms of efficiency, miniaturization, and robustness with respect misalignment between the power source and the harvester. It is expected to conclude the research activity with a novel proof-of-concept prototype at 24 GHz. This project will also be the occasion to know and explore related activities in different research premises.

Project Topic: A mm-Wave frequency-agile high-image-reject SiGe receiver for atmospheric sensing.

Project Description:

The challenge of data continuity in space-borne atmospheric remote sensing has induced a paradigm shift towards small satellites (e.g. CubeSats) for microwave radiometry of the atmosphere. In this project, we propose an integrated mm-wave frequency-agile high image-reject radiometer. To improve the resolution of this radiometer, novel co-design techniques for the integration of a Dicke switch and an LNA are investigated and a low noise front-end is designed. An avalanche noise source is also coupled on the front-end for on-chip calibrations. Such a low noise radiometer improves the quality of the measured remote sensing data and minimizes the risk of space radiometry missions by reducing the payload size, weight, power consumption and cost (SWaP-C), and enables economical manufacturing of mm-wave radiometers for the constellations of Earth-observing CubeSats.

Project Topic: Electrically tunable miniaturized frequency selective surface with smart engineered substrate.

Project Description:

This project proposes a miniaturized and electrically tunable frequency selective surface (FSS) with magneto-dielectric engineered substrate which has high and electrically tunable effective permeability. The perspective engineered substrate is implemented with multiple layers of embedded ferromagnetic (e.g., Ni₈₀Fe₂₀, Permalloy) thin film on arbitrary microwave substrate, ferromagnetic resonance frequency of magnetic film is increased with the created self-biasing magnetic field by selectively patterning magnetic thin film with a high aspect ratio. The effective permeability of the engineered substrate can be tuned by biasing direct current (DC) through the patterned gold bias lines beneath magnetic film patterns. Based on this, magnetic FSSs are proposed to be designed on the implemented engineered substrate to demonstrate the efficacy of miniaturization and electrical tunability.

Project Topic: Multi-functional transceiver architectures for future wireless systems.

Project Description:

The rapid and continuous evolution of new wireless technologies demand novel approaches in redefining the current state-of-the-art transceiver architectures and microwave components. The energy efficiency is perhaps limiting the development of most of the future wireless systems such as 5G and internet-of-things (IoT). The research aims to investigate several innovative aspects of multi-functional wireless systems for energy-efficient and configurable radio terminals. In this project, we introduce and demonstrate a low-power receiver with simultaneous wireless information and power transfer capability, a power-recycling technique in microwave mixers to harness out-of-band mixing products and a heterodyne interferometric receiver to maximize the reuse of power and building blocks. In addition, a methodology is presented to expose the latency contribution of RF front-end transceiver to next-generation mobile networks and RF-interconnects.

Project Topic: Cryo-CMOS controller for solid-state color-center qubits towards scalable quantum processors.

Project Description:

Applications of complementary metal-oxide-semiconductor (CMOS) integrated circuits in quantum systems are gaining attention due to the prospect of increased hardware scalability and reduction of cost, size, and power. This project proposes a novel cryogenic-CMOS (Cryo-CMOS) architecture to perform the microwave control of individual solid-state color-center qubits (e.g., nitrogen-vacancy centers in diamond). These color centers are integrated into diamond waveguides attached to the top of the CMOS chip, where each waveguide contains a single qubit. We also investigate extending this architecture towards a multi-qubit controller that can simultaneously address individual color centers. In addition, we propose to communicate with the cryostat through low-power wireless transceivers, reducing the heat transfer loss due to the conductive links. The proposed system opens the door for significant opportunities in quantum communications, computing and sensing.

Project Topic: AlN/GaN/AlN HEMT MMICs for applications above 100 GHz.

Project Description:

GaN high-electron-mobility transistors (HEMTs) are increasingly being used in commercial (5G and beyond) and defense (radar, satellite) systems, although they remain relatively expensive and unreliable. However, as applications above 100 GHz begin to emerge, the footprint of GaN MMICs becomes small enough to be affordable. Following the development of GaAs MMICs, GaN MMICs promise better parasitic control and system reliability. Meanwhile, at the device level, we have replaced conventional AlGaN/GaN HEMTs with AlN/GaN/AlN HEMTs. The wide bandgap of AlN improves carrier density and breakdown voltage; the higher thermal conductivity of AlN improves reliability. Despite the challenge in AlN growth, together with my colleagues at Cornell University, we have demonstrated AlN/GaN/AlN HEMTs with cutoff frequencies above 200 GHz and output power of 3 W/mm on both Si and SiC substrates.  Further work to demonstrate > 500 GHz AlN/GaN/AlN HEMTs and > 100 GHz MMICs is in progress.

Project Topic: Digital-analog hybrid spatial linearization technique for massive MIMO systems.

Project Description:

Linearization techniques are indispensable in wireless systems to compensate for the nonlinear distortion generated by power amplifiers (PAs). Due to its flexibility and outstanding linearization ability, digital predistortion (DPD) has become the most popular linearization technique in wireless systems. In massive multiple input–multiple output (MIMO) systems, state-of-the-art DPD techniques suffer from significant performance loss in terms of linearization effectiveness and power consumption, because of the increase in signal bandwidth, the introduction of phased array and hybrid beamforming (HBF) architecture, etc. Thus, DPD techniques need to be evolved to be adapted in massive MIMO systems, and some creative linearity enhancement techniques are needed to simultaneously improve the compensation accuracy and reduce the power consumption. The aim of this project is to investigate the nonlinear mechanisms of massive MIMO array and then to develop a new technical route for linearization techniques with better linearization performance and low computational/hardware complexity that can be practically implemented in massive MIMO systems.

Project Topic: High angular resolution method for coherent FMCW MIMO radar networks.

Project Description:

In this project, we investigate the feasibility of a high angular resolution digital beamforming method for coherent frequency-modulated continuous-wave (FMCW) multiple-input multiple-output (MIMO) radar networks. The proposed coherent radar network system consists of two separate FMCW radars, where each radar unit comprises N_TX transmit and N_RX receive antennas. The proposed method will combine two separate FMCW radars to an FMCW radar network with 2N_TX x 2N_RX virtual antennas for MIMO applications. The proposed method does not depend on the distance between two separate radars. The distance is arbitrary and this will enable us to increase the number of radars in coherent FMCW MIMO radar networks in the future.

Project Topic: Application of ferromagnetic/ferroelectric material to design reconfigurable components for multi-parameter smart millimeter-wave systems.

Project Description:

His project aims to employ ferromagnetic and ferroelectric material to design multi-parameter reconfigurable front-end for mm-Wave band communication paving the way toward smart mm-Wave communication. The reconfigurable parameters can be the operation frequency, power, bandwidth, or polarization. This will enable an smart system to reduce the interference, increase the transmission capacity or self-compensate any characteristics deviation (e.g. changes caused by environmental effects) via intelligent resource management. This is the most beneficial for future multi-standard communication networks (e.g. 5G) that employ mm-Wave communication for different applications and scenarios.

Project Topic: Millimeter-wave sparse digital array for imaging at more than 250 frames per second.

Project Description:

The objective of this research is to design, build, and experimentally validate a millimeter-wave digital array system with interferometric processing and active noise illumination that can provide imaging at more than 250 frames per second. Microwave and millimeter- wave imaging have been traditionally associated with limited scanning speeds. Prior work has shown that it is possible to create imagery employing interferometry algorithms, by mimicking the properties of thermal radiation using noise transmitters. In this work, by combining the benefits of passive and active millimeter-wave imaging, I propose to design and build a digital receive array in combination with an incoherent transmitt array, and an imaging algorithm that can provide image reconstruction orders of magnitude faster than the current state of the art.

Project Topic: Wideband high data-rate digital transmitter array with enhanced peak/average efficiency in CMOS technology for wireless applications.

Project Description:

Future wireless communication transmitter array systems require wideband operation to support multi-standards and higher data-rate with higher average efficiency. This research aims to achieve a wideband high data-rate digital transmitter array with enhanced peak/average efficiency, which is capable of multi-standards for different applications. As the result of proposed research plan, the proposed wideband high data-rate digital transmitter array with enhanced peak/average efficiency for wireless applications will be implemented and verified using CMOS technology for microwave wireless systems.

Project Topic: A thermal actuation/sensing array through efficient and localized heating of magnetic nanoparticles for tumor ablation and neural stimulation.

Project Description:

Localized thermal stress has wide biomedical applications such as tumor ablation and non-invasive neural modulation. However, predominant technologies including dielectric heating and ohmic heating suffer from limited control of spatial extent of the thermal stress which causes damage to surrounding healthy tissues or undesired temperature rise in non-targeted regions. Magnetic heating is an emerging technology utilizing magnetic nanoparticles (MNP) to generate localized thermal stress in response to an external alternating magnetic field. Compared to dielectric heating or ohmic heating, MNP-based magnetic heating offers superior specificity because most of the biological samples are non-magnetic. However, existing MNP-based thermal applicators rely on benchtop magnetic generators at KHz-MHz frequencies, which face two daunting challenges – heating efficiency and spatial resolution. To overcome these challenges, we propose a CMOS microscopic-scale thermal actuation/sensing array based on ferromagnetic resonance of MNP at GHz

microwave frequencies. The proposed system features high energy efficiency, submillimeter spatial resolution, thermal regulation, reconfigurable frequency and magnetic field strength, and a scalable actuation/sensing area, which would be widely applicable in biomedical and clinical applications that require highly localized thermal stress with a cellular-level resolution.

Project Topic: Radiofrequency coils based on high permittivity materials with low losses and/or metamaterials for improved sensitivity MRI.

Project Description: 

Magnetic resonance imaging (MRI) today is a promising tool for medical imaging, due to the high information content and accuracy of data acquisition. At the same time, MRI is a non-invasive and relatively safe method of medical diagnostics for patients’ health. Currently, human MR examinations are becoming highly specialized with a pre-defined and often relatively small target in the body. Conventionally, clinical MR equipment is designed to be universal that compromises its efficiency for small targets. It makes it difficult to diagnose and prescribe treatment for radiologists.

The project is focused on the first application of an artificial-dielectric in a volume coil design for the lower extremities of a person, which operate on two nuclei (31P and 1H), which gives a unique opportunity to study metabolic and microvascular functions in skeletal muscle tissue using measurements of phosphorus and hydrogen protons. The artificial-dielectric resonator operates as a passive wireless structure which is electromagnetically coupled with the body transmit coil on a commercial 3 Tesla clinical MRI system.

The design and prototype was developed of a wireless RF dual-frequencies coil that significantly increase the signal-to-noise ratio (SNR) and image resolution at the same magnetic field strength, as well as reduce scan time at the same image quality.

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.

Project topic: Broadband electrical sensing of nuclear morphology and DNA content in a single live cell.

Project Description: Morphological and structural changes of cell nuclei as well as DNA content are well-known screening, diagnostic and prognostic markers in cancer cytology. Currently, abnormalities in nuclear morphology and DNA content are mostly determined through optical microscopy and flow cytometry, which almost always require cell labeling, and, hence, are label intensive and terminal tests. A critical question will be if alteration of nuclear morphology and DNA content can be sensed without labeling. Therefore, broadband electrical sensing of single biological cells is proposed in this research to answer the critical question. A stochastic multi-scale model will be developed to understand the interaction of electric fields with cell membrane, cytoplasm and nucleus, including variation of the shape, size and location of the nucleus as well as its DNA content. Broadband electrical sensing and signal analysis of single live human cells will be performed to validate the multi-scale model and extract nuclear morphology and DNA content. Such a label-free technique not only will increase the speed and accuracy of cancer diagnosis over label-dependent optical techniques, but also will enable real-time dynamic monitoring of cancer cell nuclei, which will contribute to fundamental understanding of cell development and malignancy progression.

Project topic: Early skin cancer detection: from desktop imaging setup to real-time handheld device.

Project Description: Skin cancer is the most common cancer in the United States and current estimates indicate that one in five Americans will develop skin cancer in their lifetime according to American Academy of Dermatology. Skin cancers diagnosed and treated early enough are highly curable, and for this reason routine skin exams are highly recommended by dermatologists. Nowadays, skin biopsy is widely used to diagnose suspicious lesions principally due to its accuracy. Despite this, there is a compromise between the advantages and the risk of using this diagnosis process since any medical procedure that involves cutting the skin can be painful and conveys the risk of infection or bleeding. For this reason, the cancer diagnosis industry is experiencing a growth in non-invasive diagnosis techniques, and this trend is expected to continue. Ultra-wideband millimeter-wave (mm-wave) biomedical imaging has recently shown a great promise to provide ultra-high-resolution images for early skin cancer diagnosis. The objective of the proposed project is to develop the next generation of the ultra-wideband millimeter-wave skin cancer diagnosis systems. The proposed system will tackle the most significant challenges that have impeded this technology from entering the $5.3-billion diagnostic market for the most common cancer in the United States. A real-time and portable device equipped with custom-designed hardware and software will be developed. This device will be the first portable and affordable biomedical imaging device capable of producing real- time and ultra-high-resolution images. The novel device will allow point-of-care testing with instant availability of results to make immediate and informed decisions about patient care. It will significantly reduce the size and cost and enhance the assessment speed, convenience, and performance of the current desktop mm-wave skin cancer detection system. The device will be tested on 60 patients in tight collaboration with surgeons from Hackensack University Medical Center, NJ, USA. In addition to ex-vivo experiments for benign tissues and different types of skin cancers such as melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC), the performance of the novel device will be studied in in-vivo scenarios.