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Here we consider a disordered system of interacting quantum dots — nanoscale semiconductors with wide applicability in systems ranging from lasing to quantum computing to biological contrast imaging and next-generation displays. Quantum dots facilitate absorptive and emissive processes at specific frequencies over timescales independent of those in the incident radiation; by treating the system semiclassically...
We discuss a new electromagnetic particle-in-cell algorithm for the simulation of Maxwell-Vlasov equations on unstructured grids. The use of discrete exterior calculus and differential forms of various degrees enables numerical charge conservation from first principles, down to the numerical precision floor. In addition, energy conservation is obtained via a symplectic field update. The algorithm...
Wireless communications are expected to take place in increasingly complicated scenarios, such as dense urban, forest, tunnel and other significant cluttered environments. A key challenge emerging is to understand the physics and characteristics of wireless channels in complex environments, which are critical for the analysis, design, and application of future mobile and wireless communication systems...
A rigorous yet computationally efficient three-dimensional numerical method has been proposed based on modified alternating-direction-implicit (ADI) finite difference time domain methods (FDTD) and it has the capability of modeling the eccentric property of magnetic material being anisotropic, dispersive or nonlinear. The proposed algorithm solves Maxwell's equations and LLG equations simultaneously,...
Recently, microwave heating has shown promise as a potential source of thermal energy to drive the materials manufacturing process known as sintering. We present here a two-dimensional model of microwave sintering that describes the physical phenomena that influence the process (i.e., electromagnetics, heat transfer and mechanical deformation), including the influence that temperature and relative...
We demonstrate a wideband and high power distributed amplifier (DA) using an indium phosphide (InP) double heterojunction bipolar transistor (HBT) process. For the first time, a triple stack HBT topology is used in an InP DA to achieve high power and high linearity. The 1.2 mm × 0.7 mm fabricated chip exhibits a measured gain of 16 dB, maximum output power of 19.5 dBm and output third order intercept...
A 4–10 GHz fully-integrated power amplifier (PA) is demonstrated using a 0.15-μm GaAs pHEMT process. This PA employs a compact structure with 4-parallel 3-stacked-FET cells to obtain a broadband power performance within a very small chip size. The measurement results of this PA in the frequency range of 4–10 GHz show a gain flatness of 13.5±1.5 dB, a maximum input return loss (S11) of −9 dB, a maximum...
This work presents the design and implementation of a flat-gain, efficient and wideband stacked distributed power amplifier (SDPA) in 0.13um CMOS technology. To obtain high output swing along with a reasonable gain, a four-transistor stack is utilized in four sections. Voltage alignment at the drain of each device in the stack is obtained by allowing a small AC swing at the gate due to voltage division...
A fully integrated K-band transformer based power amplifier with neutralization technique is proposed and fabricated in 90-nm CMOS technology. Several cascode cells are combined together as differential power cells. On-chip transformers and current combing topology are used to combine amplifiers as well as to reduce the problem of output power loss. In order to improve the overall stability, neutralization...
First-ever realization of a W-band power amplifier (PA) millimeter-wave monolithic integrated circuit (MMIC) utilizing GaN-based Tri-gate high-electron-mobility transistors (HEMTs) is presented in this paper. Superior device- and circuit-level performances over conventional GaN HEMTs are proven to be empowered through implementation of the novel Tri-gate topology which exhibits a 3-dimensional gate...
A new and versatile 3D printed on-chip integration approach using laser machining is demonstrated in this paper for microwave and mm-wave systems. The integration process extends interconnects laterally from a MMIC to a chip carrier. Laser machining techniques are studied and characterized to enhance the 3D printing quality. Specifically, the width of microdispensed printed traces is accurately controlled...
Traditional hollow metallic waveguide manufacturing techniques are readily capable of producing components with high-precision geometric tolerances, yet generally lack the ability to customize individual parts on demand or to deliver finished components with low lead times. This paper proposes a Rapid-Prototyping (RP) method for relatively low-loss millimeter-wave hollow waveguides produced using...
Additive manufacturing allows for fabrication of highly complex structures that efficiently use a 3D volume of space. Current state of the art metal additive manufacturing methods such as Selective Laser Melting (SLM) allow for intricate parts with high mechanical strength but at the cost of increased surface roughness on internal faces of waveguide structures. This paper investigates the contribution...
This work reports on the integration of RF functionalities in microwave waveguide components through the selective laser melting process. A specific integrated component has been developed for the relevant application domain of satellite communications. The component operates in the Ku-K bands and integrates a H-plane bend, a 90-deg twist and ninth-order pass-band filter. The AlSi10Mg prototype manufactured...
This paper presents several W-band (75–110 GHz) WR-10 waveguide components fabricated using both direct metal laser sintering (DMLS) and stereolithography (SLA), in aluminum, nickel and copper alloys and metal-coated plastic (MCP). The RF performance and surface roughness are measured, and the loss due to surface roughness quantified. The measured loss at 95 GHz ranges from 0.055 dB/cm for the copper-plated...
This paper compares two radar configurations with different antenna systems for measuring particle streams in the near field range. A complex source beam is employed to describe the field characteristics. This new approach is used to derive the associated antenna gain and power patterns and applied in the radar equation for particle streams. We demonstrate how indoor measurements benefit from a bistatic...
A 77-GHz Doppler shift radar is demonstrated based on an Active Quasi-Circulator (QC) monostatic approach. The QC system includes a leakage canceler as well as a modulator for time division IQ switching. A flexible decimation chain, implemented in an FPGA, facilitates the use of a low cost ADC with moderate SNR performance. By analyzing the drift behavior of the system, the parameters for an appropriate...
This paper presents a Ku-band (14–16 GHz) CMOS frequency modulated continuous-wave (FMCW) radar transceiver developed to measure snow depth for water management purposes and to aid in retrieval of snow water equivalent (SWE). An on-chip direct digital frequency synthesizer (DDFS) and digital-to-analog converter (DAC) digitally generates the chirping waveform which then drives a ring oscillator based...
In this paper, the integration of a communication link for a modulated-reflector radar is presented. This kind of radar system is intended to determine the position of multiple semi-passive backscatter reflector nodes, designed to be mounted on different objects of interest. A method to transport information from these objects back to the radar-basestation is sketched, using the available hardware-resources...
High-speed communication systems nowadays often face technological limitations, e.g., when operating at very high center frequencies or when adopting novel processes like printed transistors. These scaling issues often result in low single-stage amplifier gain, which makes classic broadband communication architectures, most notably the homodyne transceiver, inefficient in terms of power consumption,...
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