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With the development of modern wireless communications, interference has become a primary challenge for spectrum utilization and coexistence. High frequency-selectivity, tunable, low-noise, and high-linearity RF front-end components can greatly help the reception robustness under heavy interference scenarios. In this work, we propose to utilize the parametric mixing and amplification behavior of the time-varying transmission lines (TVTL) to design and implement such devices.TVTLs are reactance-based circuits consisting of passive transmission lines whose inductance or capacitance is modulated by an electromagnetic wave called the “pump”. The single-sideband operation of a TVTL is especially favorable in that it can provide low-noise parametric amplification and frequency conversion with a moderate amount of gain. Moreover, TVTLs are compatible with modern IC technologies and can be realized with small form factors. In this work, an in-depth theoretical study on the time-varying transmission lines (TVTL) in the single-sideband operation is presented. The theory then serves as a guideline to design three configurations of TVTLs on commercially available monolithic microwave integrated circuit (MMIC) processes. These MMIC TVTLs are then applied to design the RF correlator with either the frequency translational approach or the tunable peak amplifier approach to overcome the interference issues faced by modern receivers. Measurements results showed that 0 dB conversion loss was realized in the directly-pumped TVTL frequency translational correlator prototype. >25 dB correlation suppression was also achieved by the same prototype when comparing the reception of the correlated signal with the reception of the uncorrelated (orthogonal) signal. For the tunable peak amplifier approach, experiments indicated that the peak gain of the tunable peak amplifier was >25 dB with a bandwidth 100 MHz. The noise figure of the tunable peak amplifier in both simulation and measurement was

This work demonstrates the design of a MMIC solid state class-A power amplifier in 250nm InP HBT technology achieving 0.5W saturated output power at 238 GHz at compressed gain of 14dB and power added efficiency of 10%. The 3dB bandwidth is 230 GHz to 242GHz. The power amplifier uses 4:1 travelling wave combiner to combine the output power of 8 power cells. Each power cell is a 3-stage cascaded amplifier with 2 common-base gain stage and 1 common emitter power stage.

The need for high power, highly efficient, multi-band and multi-mode radio frequency (RF) and microwave power amplifiers in the commercial and defense wireless industries continues to drive the research and development of gallium nitride (GaN) devices and their implementation in the receiver and transmitter lineups of modern microwave systems. Unlike silicon (Si) or gallium arsenide (GaAs), GaN is a direct wide bandgap semiconductor that permits usage in high voltage and therefore high power applications. Additionally, the increased saturation velocity of GaN allows for operation well into the super high frequency (SHF) portion of the RF spectrum. For the power amplifier designer, active devices utilizing GaN will exhibit power densities almost an order of magnitude greater than comparably sized GaAs devices and almost two orders of magnitude greater than Si devices. Not only does this mean an overall size reduction of an amplifier for a given output power, but it allows GaN to replace specialized components such as the traveling-wave tube (TWT) and other circuits once deemed impossible to realize using solid-state electronics. Designs utilizing GaN in amplifiers, switches, mixers, etc., are able to meet the continually shrinking size, increased power, stringent thermal, and cost requirements of a modern microwave system.There are two relatively straight forward methods used to investigate the intrinsic power scaling properties of a GaN high-electron-mobility transistor (HEMTs) configured as a common source amplifier. The first method involves sweeping the applied drain to source voltage bias and the second method involves scaling the physical size of the transistor. The prior method can be used to evaluate fixed sized transistors while the latter method requires an understanding of the obtainable power density for a given device technology prior to fabrication. Since the power density is also a function of the drain to source voltage bias, an initial iterative component of the design cycle may be required to fully characterize the device technology. If a scalable nonlinear device model is available to the designer, the harmonic balance simulator in most computer aided design (CAD) tools can be used to evaluate device parameters such as the maximum output power and power added efficiency (PAE) using large signal load pull simulations.The circuits presented in this thesis address two power amplifier design approaches commonly used in industry. The first approach utilizes commercially available bare die GaN transistors that can be wire-bonded to matching circuitry on a printed circuit board (PCB). This technique is known as hybrid packaging. The second approach utilizes a fully integrated design or monolithic microwave integrated circuit (MMIC) and the process design kit (PDK) used to design, simulate and layout the power amplifier circuitry before submission to a foundry for fabrication. In both cases, the nonlinear transistor models are used to investigate the power scalability of class E mode GaN power amplifiers and the techniques used to implement such circuits. The design, results, and challenges of each approach are discussed and future work is presented.

The development of millimeter-wave (30-300 GHz) sensors and communications systems has a long history of interest, spanning back almost six decades. In particular, mm-wave radars have applications as automotive radars, in remote atmospheric sensing applications, as landing radars for air and spacecraft, and for high precision imaging applications. Mm-wave radar systems have high angular accuracy and range resolution, and, while susceptible to atmospheric attenuation, are less susceptible to optically opaque conditions, such as smoke or dust. This dissertation document will present the initial steps towards a new approach to the creation of a mm-wave radar system at 94 GHz. Specifically, this dissertation presents the design, fabrication and testing of various components of a highly integrated mm-wave a 94 Ghz monopulse radar transmitter/receiver. Several architectural approaches are considered, including passive and active implementations of RF monopulse comparator networks. These architectures are enabled by a high-performance three-dimensional rectangular coaxial microwave transmission line technology known as PolyStrataTM as well as silicon-based IC technologies. A number of specific components are examined in detail, including: a 2x2 PolyStrata antenna array, a passive monopulse comparator network, a 94 GHz SiGe two-port active comparator MMIC, a 24 GHz RF-CMOS 4-port active monopulse comparator IC, and a series of V- and W-band corporate combining structures for use in transmitter power combining applications. The 94 GHz cavity-backed antennas based on a rectangular coaxial feeding network have been designed, fabricated, and tested. 13 dB gain for a 2 x 2 array, as well as antenna patterns are reported. In an effort to facilitate high-accuracy measurement of the antenna array, an E-probe transition to waveguide and PolyStrata diode detectors were also designed and fabricated. AW-band rectangular coaxial passive monopulse comparator with integrated antenna array and diode detectors have also been presented. Measured monopulse nulls of 31.4 dB in the ΔAZ plane have been demonstrated. 94-GHz SiGe active monopulse comparator IC and 24 GHz RF-CMOS active monopulse comparator RFIC designs are presented, including detailed simulations of monopulse nulls and performance over frequency. Simulations of the W-band SiGe active monopulse comparator IC indicate potential for wideband operation, with 30 dB monopulse nulls from 75-105 GHz. For the 24-GHz active monopulse comparator IC, simulated monopulse nulls of 71 dB and 68 dB were reported for the azimuthal and elevational sweeps. Measurements of these ICs were unsuccessful due to layout errors and incomplete accounting for parasitics. Simulated results from a series of rectangular coaxial power corporate power combining structures have been presented, and their relative merits discussed. These designs include 2-1 and 4-1 reactive, Wilkinson, and Gysel combiners at V- and W-band. Measured back-to-back results from Gysel combiners at 60 GHz included insertion loss of 0.13 dB per division for a 2-1 combination, and an insertion loss of 0.3 dB and 0.14 dB for "planar" and "direct" 4-1 combinations, respectively. At 94 GHz, a measured insertion loss of 0.1 dB per division has been presented for a 2-1 Gysel combination, using a back-to-back structure. Preliminary designs for a solid-state power amplifier (SSPA) structure have also been presented. Finally, two conceptual monopulse transceivers will be presented, as a vehicle for integrating the various components demonstrated in this dissertation.

The use of wide bandgap devices and circuits has increased dramatically in recent years in step with significant advancements in material quality and device technology. Devices made with silicon carbide and gallium nitride have shown exceptional chemical and electrical stability and are extremely promising high power, high temperature, and high frequency operation. The use of III-V nitride material specifically have found applications in blue and UV emission optoelectronic devices such as LEDs, semiconductor layers, as well as solar-blind sensors and reflectors. The strong piezoelectric nature of III-V nitrides also allows for their use in chemical and pressure sensors. III-V nitride devices are now in limited commercial production for optical, electronic, and sensor application. The expected demand and technological maturation for devices made form this material system is extremely promising, but there is still quite a bit of work to be done before the promise becomes a reality. In this study, the viability of GaN-based HFETs for high frequency and high power MMIC amplifier applications will be demonstrated through fabrication process optimization and investigation of HFET performance through the optimization of layer design and device geometry. DC, pulsed I-V, low frequency noise, small and large signal characterization will be used to determine optimum operation points and structures to yield optimum large signal performance. Single- and two-stage amplifiers will be designed and simulated to indicate the potential RF MMIC performance at 12GHz and 20GHz large signal operation. SAW filter fabrication and integration with active GaN HFETs devices for sensing and low frequency RF application will also be addressed.

In this research, design and processing of multi-stack three-dimensional RF coil has been investigated and developed to meet the needs of small-size high-resistance inductors. Different materials and fabrication technologies have been developed to build a three-dimensional coil structure in the most stable and efficient method. The experimented sample was built on the surface of a standard 2-inch wafer. The height of the poles is limited by the aspect ratios of the photoresist and polyimide used in the fabrication process. Both AZ4620 photoresist and PI2611 polyimide film techniques have been tried to improve the structure to the limit. An initial mask was designed to test the limitation of equipment and materials. A final mask with more conservative design has been fabricated and showed better results. In order to correctly evaluate the efficiency of the experimented sample, a simple model has been developed to estimate the magnetic fields generated by the coil. More precise results were obtained HFSS® software. The final samples were measured with a Vector Network Analyzer to provide two port S-Parameters. Inductance value was manually calculated and also simulated with Agilent ADS. Some suggestions have also been made in the final chapter about how to further improve the processing of the three-dimensional coil.

In this thesis several passive and active MMIC structures are designed, fabricated and tested in order to develop a monolithic transmit/receive system residing on a single chip with enhanced performance at millimeter-wave frequencies. The capability of applying micromachining to improve the efficiency of microstrip patch antennas on high index materials such as silicon, GaAs, or InP is validated. Patch antennas on Duroid substrates resonating at 13 GHz with 64% and 28% increase in impedance bandwidth and efficiency, respectively, as well as smooth radiation patterns are successfully demonstrated by creating a cavity underneath the antenna. The importance of the placement of the cavity relative to the radiating edges of the antenna in order to improve the efficiency is also shown. A minimum distance equal to two times the substrate thickness is required. A planar micromachined resonator on silicon with a high quality factor, Q, at 10.4 GHz is also fabricated and tested; the measured Q is 506 while the insertion loss and the bandwidth are 0.36 dB and 5%, respectively. A bandwidth of 2% with a loss of 1.1 dB is also achieved for a slightly different topology of the micromachined resonator. Insertion loss measurements under different temperature ambients showed a negligible drift in the resonant frequency. Regarding active structures, Finite Ground Coplanar line based monolithic multipliers and mixers operating in W-band are designed, fabricated and tested. The performance of FGC lines on GaAs and quartz substrate with a polyimide overlay for passivation is first investigated. Experimental results that show the dependence of the line characteristics on the geometry rather than the substrate material are presented. Next, a Q = 2 monolithic doubler with 17.2% efficiency, 10% minimum bandwidth and 66 mW output power, as well as a Q = 3 doubler with 22% efficiency, 8.5% bandwidth and 50 mW output power in W-band are demonstrated. A doubler from 37.5 to 75 GHz that implements four diodes with a 12.5% efficiency and an output power of 115 mW is also presented. Furthemore, a method that increases the efficiency of monolithic multipliers by reducing the loss of the FGC lines is shown. Finally, a monolithic mixer residing on the same material with the multipliers is fabricated and tested. A novel fabrication technique that combines channel etched diodes of small areas with air-bridges for the passive circuits is developed. A single-sideband conversion loss of 11 dB is achieved at 79 GHz for an IF frequency of 4 GHz and an LO power of 8.8 dBm.

This dissertation explores three subjects which contribute to increasing the efficiency, in terms of speed and storage, of numerical methods for electromagnetic problems. The hybrid MoM/FEM technique is first applied to the design of a microstripline-fed slot-coupled cavity-backed patch antenna, a coaxial line-fed cavity-backed patch antenna, a wide bandwidth microstripline vertical cavity coupler, and a high-Q cavity resonator. The latter was fabricated and tested to verify the theoretical results. The second is a wavelet based method of moments. Instead of ordinary basis functions, a class of bases called wavelets are used in the formulation of MoM. These wavelets are locally oscillatory and have zero average. Hence, when integrated with other smooth functions, the resulting value will be very small. When used in MoM implementations, the resulting impedance matrix will have many small off-diagonal terms which can be set to zero without adversely effecting the solution. Using sparse storage techniques, substantial memory is saved by using wavelet bases. These wavelet bases were applied to the analysis of patch antenna arrays, leading to large memory savings. Parallel computers were applied to speed up the computation process. The idea of parallelization is to divide a single task to many independent jobs. The communication between the jobs must be minimal to avoid the overhead incurred by the slower (compared to the speed of CPU) communication link. The matrix filling process and the fast wavelet transform (FWT) were two processes suitable for parallelization. These processes were implemented in the C++ language using a portable and standard Message Passing Interface.

All microwave and millimeter-wave systems are made of monolithic microwave integrated circuits (MMICs) which are placed together using bond wires and discrete transmission line components (such as filters and couplers) to form microwave integrated circuits and subsystems. Most of the problems encountered in microwave circuits, being at the MMIC level or at the hybrid circuit implementation level, are due to the presence of the underlying dielectric substrate. In this thesis, we propose the use of micromachining techniques to eliminate the dielectric substrate and to create a localized low-loss and low-$\rm\epsilon\sb{r}$ environment. The idea attacks the most basic point: How to build microwave planar circuits on very low dielectric constant substrates to eliminate dispersion and dielectric loss and to result in a TEM-wave, while still being compatible with standard silicon and GaAs processing techniques. The low-$\rm\epsilon\sb{r}$ environment is accomplished by depositing a 1-2$\mu$m-thick dielectric membrane layer on top of the dielectric substrate, then using micromachining techniques to locally remove the supporting silicon or GaAs substrate. By using this technology, a membrane suspended 1-2 nH inductor has shown a resonant frequency of 60 GHz which is around three times higher than the same inductor built on a silicon substrate. This technology is also applied to the design of interdigitated resonators and filters which achieved conductor-loss limited performance at 15-40 GHz. A 20.3 GHz 16% bandwidth filter is presented and results in a measured port-to-port conductor-loss limited insertion loss of 1.7 dB. A Lange-coupler employing the membrane technology is also built and a $3.6\pm0.8$ dB port-to-port coupling bandwidth from 6.5 to 20 GHz is achieved while preserving a phase balance of $90\pm3$ degree. The micromachined interdigitated filter and Lange-coupler are used in a Ku-band single-sideband mixer. This SSB mixer achieves a 9.5 dB port-to-port conversion loss at 17 GHz with an image rejection of 30 dB for an IF of 1 GHz and above, requires no DC bias and 1-2 mW of LO power. This technology is fully compatible with the via-hole process in Silicon, SiGe, GaAs and InP MMICs, and can result in high performance millimeter-wave ICs suitable for high volume productions.