Dynamically Controllable Integrated Radiation and Self-Correcting Power Generation in mm-Wave Circuits and Systems

This thesis presents novel design methodologies for integrated radiators and power generation at mm-wave frequencies that are enabled by the continued integration of various electronic and electromagnetic (EM) structures onto the same substrate. Beginning with the observation that transistors and their connections to EM radiating structures on an integrated substrate are essentially free, the concept of multi-port driven (MPD) radiators is introduced, which opens a vast design space that has been generally ignored due to the cost structure associated with discrete components that favors fewer transistors connected to antennas through a single port. From Maxwell's equations, a new antenna architecture, the radial MPD antennas based on the concept of MPD radiators, is analyzed to gain intuition as to the important design parameters that explain the wide-band nature of the antenna itself. The radiator is then designed and implemented at 160 GHz in a 0.13 um SiGe BiCMOS process, and the single element design has a measured effective isotropic radiated power (EIRP) of +4.6 dBm with a total radiated power of 0.63 mW. Next, the radial MPD radiator is adapted to enable dynamic polarization control (DPC). A DPC antenna is capable of controlling its radiated polarization dynamically, and entirely electronically, with no mechanical reconfiguration required. This can be done by having multiple antennas with different polarizations, or within a single antenna that has multiple drive points, as in the case of the MPD radiator with DPC. This radiator changes its polarization by adjusting the relative phase and amplitude of its multiple ports to produce polarizations with any polarization angle, and a wide range of axial ratios. A 2x1 MPD radiator array with DPC at 105 GHz is presented whose measurements show control of the polarization angle throughout the entire 0 degree through 180 degree range while in the linear polarization mode and maintaining axial ratios above 10 dB in all cases. Control of the axial ratio is also demonstrated with a measured range from 2.4 dB through 14 dB, while maintaining a fixed polarization angle. The radiator itself has a measured maximum EIRP of +7.8 dBm, with a total radiated power of 0.9 mW, and is capable of beam steering. MPD radiators were also applied in the domain of integrated silicon photonics. For these designs, the driver transistor circuitry was replaced with silicon optical waveguides and photodiodes to produce a 350 GHz signal. Three of these optical MPD radiator designs have been implemented as 2x2 arrays at 350 GHz. The first is a beam forming array that has a simulated gain of 12.1 dBi with a simulated EIRP of -2 dBm. The second has the same simulated performance, but includes optical phase modulators that enable two-dimensional beam steering. Finally, a third design incorporates multi-antenna DPC by combining the outputs of both left and right handed circularly polarized MPD antennas to produce a linear polarization with controllable polarization angle, and has a simulated gain of 11.9 dBi and EIRP of -3 dBm. In simulation, it can tune the polarization from 0 degrees through 180 degrees while maintaining a radiated power that has a 0.35 dB maximum deviation from the mean. The reliability of mm-wave radiators and power amplifiers was also investigated, and two self-healing systems have been proposed. Self-healing is a global feedback method where integrated sensors detect the performance of the circuit after fabrication and report that data to a digital control algorithm. The algorithm then is capable of setting actuators that can control the performance of the mm-wave circuit and counteract any performance degradation that is observed by the sensors. The first system is for a MPD radiator array with a partially integrated self-healing system. The self-healing MPD radiator senses substrate modes through substrate mode pickup sensors and infers the far-field radiated pattern from those sensors. DC current sensors are also included to determine the DC power consumption of the system. Actuators are implemented in the form of phase and amplitude control of the multiple drive points. The second self-healing system is a fully integrated self-healing power amplifier (PA) at 28 GHz. This system measures the output power, gain and efficiency of the PA using radio frequency (RF) power sensors, DC current sensors and junction temperature sensors. The digital block is synthesized from VHDL code on-chip and it can actuate the output power combining matching network using tunable transmission line stubs, as well as the DC operating point of the amplifying transistors through bias control. Measurements of 20 chips confirm self-healing for two different algorithms for process variation and transistor mismatch, while measurements from 10 chips show healing for load impedance mismatch, and linearity healing. Laser induced partial and total transistor failure show the benefit of self-healing in the case of catastrophic failure, with improvements of up to 3.9 dB over the default case. An exemplary yield specification shows self-healing improving the yield from 0% up through 80%.</p

Digitally-Assisted RF IC Design Techniques for Reliable Performance

Semiconductor industries have competitively scaled down CMOS devices to attain benefits of low cost, high performance, and high integration density in digital integrated circuits. On the other hand, deep scaled technologies inextricably accompany a large process variation, supply voltage scaling, and reduction in breakdown voltages of transistors. When it comes to RF/analog IC design, CMOS scaling adversely affects its reliability due to large performance variation and limited linearity. For addressing the issues related to variations and linearity, this research proposes the following digitally-assisted RF circuit design techniques: self-calibration system for RF phase shifters and wide dynamic range LNAs. Due to PVT variations in scaled technologies, RF phase shifter design becomes more challenging with device scaling. In the proposed self-calibration topology, we devised a novel phase sensing method and a pulsewidth-to-digital converter. The feedback controller is also designed in digital domain, which is robust to PVT variations. These unique techniques enable a sensing/control loop tolerant to PVT variations. The self-calibration loop was applied to a 7 to 13GHz phase shifter. With the calibration, the estimated phase error is less than 2 degrees. To overcome the linearity issue in scaled technologies, a digitally-controlled dual-mode LNA design is presented. A narrowband (5.1GHz) and a wideband (0.8 to 6GHz) LNA can be toggled between high-gain and high-linearity modes by digital control bits according to the input signal power. A compact design, which provides negligible performance degradation by additional circuitry, is achieved by sharing most of the components between the two operation modes. The narrowband and the wideband LNA achieves an input-referred P1dB of -1.8dBm and +4.2dBm, respectively

Electromagnetic Energy Coupled to Nanomaterial Composites for Polymer Manufacturing

Polymer nano-composites may be engineered with specific electrical properties to achieve good coupling with electromagnetic energy sources. This enables a wide range of novel processing techniques where controlling the precise thermal profile is critical. Composite materials were characterized with a variety of electrical and thermographic analysis methods to capture their response to electromagnetic energy. COMSOL finite element analysis software was used to model the electric fields and resultant thermal profiles in selected samples. Applications of this technology are demonstrated, including the use of microwave and radio frequency energy to thermally weld the interfaces of 3D printed parts together for increased interlayer (Z) strength. We also demonstrate the ability to bond various substrates with carbon nanotube/epoxy composite adhesives using radio frequency electromagnetic heating to rapidly cure the adhesive interface. The results of this work include 3D printed parts with mechanical properties equal to injection molded samples, and RF bonded joints cured 40% faster than traditional oven curing

An Energy-Efficient Reconfigurable Mobile Memory Interface for Computing Systems

The critical need for higher power efficiency and bandwidth transceiver design has significantly increased as mobile devices, such as smart phones, laptops, tablets, and ultra-portable personal digital assistants continue to be constructed using heterogeneous intellectual properties such as central processing units (CPUs), graphics processing units (GPUs), digital signal processors, dynamic random-access memories (DRAMs), sensors, and graphics/image processing units and to have enhanced graphic computing and video processing capabilities. However, the current mobile interface technologies which support CPU to memory communication (e.g. baseband-only signaling) have critical limitations, particularly super-linear energy consumption, limited bandwidth, and non-reconfigurable data access. As a consequence, there is a critical need to improve both energy efficiency and bandwidth for future mobile devices.;The primary goal of this study is to design an energy-efficient reconfigurable mobile memory interface for mobile computing systems in order to dramatically enhance the circuit and system bandwidth and power efficiency. The proposed energy efficient mobile memory interface which utilizes an advanced base-band (BB) signaling and a RF-band signaling is capable of simultaneous bi-directional communication and reconfigurable data access. It also increases power efficiency and bandwidth between mobile CPUs and memory subsystems on a single-ended shared transmission line. Moreover, due to multiple data communication on a single-ended shared transmission line, the number of transmission lines between mobile CPU and memories is considerably reduced, resulting in significant technological innovations, (e.g. more compact devices and low cost packaging to mobile communication interface) and establishing the principles and feasibility of technologies for future mobile system applications. The operation and performance of the proposed transceiver are analyzed and its circuit implementation is discussed in details. A chip prototype of the transceiver was implemented in a 65nm CMOS process technology. In the measurement, the transceiver exhibits higher aggregate data throughput and better energy efficiency compared to prior works

SiGe BiCMOS RF front-ends for adaptive wideband receivers

The pursuit of dense monolithic integration and higher operating speed continues to push the integrated circuit (IC) fabrication technologies to their limits. The increasing process variation, associated with aggressive technology scaling, is having a negative impact on circuit yield in current IC technologies, and the problem is likely to become worse in the future. Circuit solutions that are more tolerant of the process variations are needed to fully utilize the benefits of technology scaling. The primary goal of this research is to develop high-frequency circuits that can deliver consistent performance even under the threat of increasing process variation. These circuits can be used to build ``self-healing" systems, which can detect process imperfections and compensate accordingly to optimize performance. In addition to improving yield, such adaptive circuits and systems can provide more robust and efficient solutions for a wide range of applications under varying operational and environmental conditions.Silicon-germanium (SiGe) BiCMOS technology is an ideal platform for highly integrated systems requiring both high-performance analog and radio-frequency (RF) circuits as well as large-scale digital functionality. This research is focused on designing circuit components for a high-frequency wideband self-healing receiver in SiGe BiCMOS technology. An adaptive image-reject mixer, low insertion-loss switches, a wideband low-noise amplifier (LNA), and a SiGe complementary LC oscillator were designed. Healing algorithms were developed, and automated self-healing of multiple parameters of the mixer was demonstrated in measurement. A monte-carlo simulation based methodology was developed to verify the effectiveness of the healing procedure. In summary, this research developed circuits, algorithms, simulation tools, and methods that are useful for building "self-healing" systems.Ph.D

Antenna sensing for wearable applications

As wearable technologies are growing fast, there is emerging trend to increase functionality of the devices. Antennas which are primarily component in communication systems can offer attractive route forward to minimize the number of components functioning as a sensing element for wearable and flexible electronics. Toward development of flexible antenna as sensing element, this thesis investigates the development of the flexible and printed sensing NFC RFID tag. In this approach, the sensor measurement is supported by the internal sensor and analog-to-digital convertor (ADC) of the NFC transponder. Design optimisation, fabrication and characterization of the printed antenna are described. Besides, the printed antenna, NFC transponder and two simple resistive sensors are integrated to form a fully flexible sensing RFID tag demonstrating applicability in food and health monitoring. This thesis also presents development of two antenna sensors by using functional materials: (i) An inductor-capacitor (LC) resonant tank based wireless pressure sensor on electrospun Poly-L-lactide (PLLA) nanofibers-based substrate. The screen-printed resonant tank (resonant frequency of ~13.56 MHz) consists of a planar inductor connected in parallel with an interdigitated capacitor. Since the substrates is piezoelectric, the capacitance of the interdigitated capacitor varies in response to the applied pressure. To demonstrate a potential application of developed pressure sensor, it was integrated on a compression bandage to monitor sub-bandage pressure. (ii) To investigate the realization of sensing antenna as temperature sensor simple loop antenna is designed and in this study unlike the first study that the sensing element was the substrate, the conductive body of the antenna itself is considered as a functional material. In this case, a small part of a loop antenna which originally was printed using silver paste is replaced by Poly(3,4-ethylenedioxythiophene): polystyrene (PEDOT: PSS). The sensing mechanism is based on the resonant frequency shift by varying temperature. While using functional materials is useful for realization of antenna sensor, another approach also is presented by developing stretchable textile-based microstrip antennas on deformable substrate which can measure joint angles of a human limb. The EM characteristics of the meshed patch antenna were compared with its metallic counterpart fabricated with lithography technique. Moreover, the concept of stretchable UHF RFID-based strain sensor is touched in the final part of this thesis

1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance

Multi-Frequency Modulation and Control for DC/AC and AC/DC Resonant Converters

Harmonic content is inherent in switched-mode power supplies. Since the undesired harmonics interfere with the operation of other sensitive electronics, the reduction of harmonic content is essential for power electronics design. Conventional approaches to attenuate the harmonic content include passive/active filter and wave-shaping in modulation. However, those approaches are not suitable for resonant converters due to bulky passive volumes and excessive switching losses. This dissertation focuses on eliminating the undesired harmonics from generation by intelligently manipulating the spectrum of switching waveforms, considering practical needs for functionality.To generate multiple ac outputs while eliminating the low-order harmonics from a single inverter, a multi-frequency programmed pulse width modulation is investigated. The proposed modulation schemes enable multi-frequency generation and independent output regulation. In this method, the fundamental and certain harmonics are independently controlled for each of the outputs, allowing individual power regulations. Also, undesired harmonics in between output frequencies are easily eliminated from generation, which prevents potential hazards caused by the harmonic content and bulky filters. Finally, the proposed modulation schemes are applicable to a variety of DC/AC topologies.Two applications of dc/ac resonant inverters, i.e. an electrosurgical generator and a dual-mode WPT transmitter, are demonstrated using the proposed MFPWM schemes. From the experimental results of two hardware prototypes, the MFPWM alleviates the challenges of designing a complicated passive filter for the low-order harmonics. In addition, the MFPWM facilitates combines functionalities using less hardware compared to the state-of-the-art. The prototypes demonstrate a comparable efficiency while achieving multiple ac outputs using a single inverter.To overcome the low-efficiency, low power-density problems in conventional wireless fast charging, a multi-level switched-capacitor ac/dc rectifier is investigated. This new WPT receiver takes advantage of a high power-density switched-capacitor circuit, the low harmonic content of the multilevel MFPWMs, and output regulation ability to improve the system efficiency. A detailed topology evaluation regarding the regulation scheme, system efficiency, current THD and volume estimation is demonstrated, and experimental results from a 20 W prototype prove that the multi-level switched-capacitor rectifier is an excellent candidate for high-efficiency, high power density design of wireless fast charging receiver

Beam scanning by liquid-crystal biasing in a modified SIW structure

A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium