Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 39 for “"very high frequency"”.
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Very High Frequency EPR: Instrument and Applications
… are performed at conventional 9 GHz or 35 GHz frequency. But there are numerous situations in which a large increase in the microwave frequency (and/or magnetic field) will result in substantial increase in the information content in EPR spectra. This has motivated us to construct a very high …
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Very-high-frequency low-voltage power delivery
… due to the desire for lower voltages, higher conversion ratios and higher bandwidth. Future computation systems also pose a major challenge in energy delivery that is difficult to meet with existing devices and design strategies. To reduce interconnect bottlenecks and enable more …
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Very High Frequency Integrated POL for CPUs
… converters are used extensively in IT products. Every piece of the integrated circuit (IC) is powered by a point-of-load (POL) converter, where the proximity of the power supply to the load is very critical in terms of transient performance and efficiency. A compact POL converter with high power …
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Design of a Very High Frequency dc-dc boost converter
… new circuit architectures operating at extreme high frequencies it becomes possible to miniaturize the passive components needed for a power converter, and to achieve dramatic improvements in converter transient performance. This thesis focuses on the development of a Very High Frequency (VHF, …
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Experimental investigation of electron multipactor discharges at very high frequency
… in both parallel plate and coaxial geometries at very high frequency (VHF). CMX provides the first detailed investigation of multipactor energy distribution functions for both coaxial and parallel plate geometries with the use of retarding potential analyzers (RPA). A 1-D particle tracking …
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Design of a very high frequency resonant boost DC-DC converter
THIS thesis explores the development of a very high frequency DC-DC resonant boost converter. The topology examined features low parts count and fast transient response but suffers from higher device stresses compared to other topologies that use a larger number of passive components. A new design …
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Design and evaluation of a very high frequency dc/dc converter
… presents a resonant boost topology suitable for very high frequency (VHF, 30-300 MHz) dc-dc power conversion. The proposed design is a fixed frequency, fixed duty ratio resonant converter featuring low device stress, high efficiency over a wide load range, and excellent transient performance. A …
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Design of class E resonant rectifiers for very high frequency power conversion
… rectifiers have important applications in very-high-frequency power conversion systems, including dc-dc converters, wireless power transfer systems, and energy recovery circuits for radio-frequency systems. In many of these applications, it is desirable for the rectifier to appear as a …
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Modelling of advanced submicron gate InGaAs/InAIAs pHEMTS and RTD devices for very high frequency applications
InP based InAlAs/InGaAs pseudomorphic High Electron Mobility Transistors (pHEMTs) have shown outstanding performances, which makes them prominent in high frequency mm-wave and submillimeter-wave applications. However, conventional InGaAs/InAlAs pHEMTs have major drawbacks, i.e., very low breakdown …
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Use of IGT/COMFET in zero current quasi resonant converters
… predominant power loss in IGT/COMFET devices for very high frequency resonant operation. Device design change is suggested for very high frequency resonant operation applications.
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A Merged two-stage power conversion architecture with switched capacitor circuit for an LED driver module
… specified to convert from wide-range and high-level DC voltage or AC line voltage to low-level DC voltage, satisfying high efficiency, high power density, and high power factor is challenging because of the higher device stress and difficulty of maintaining ZVS/ZCS conditions. Our purpose …
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Fabrication of graphene-on-GaN vertical transistors
… of graphene make it an excellent option for very high frequency electronics. However, the poor output resistance and difficult lithography of lateral transistors significantly limit its performance. In this thesis, we propose a new kind of vertical graphene base transistor to take advantage …
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An Investigation of Fundamental Frequency Limitations for HF/VHF Power Conversion
… chiefly be attributed to increases in switching frequency. It is to be expected that the trends towards miniaturization will maintain steady pressure to keep this pace of increasing switching frequencies of power converters. However certain fundamental limits in high frequency power conversion …
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Effects of the troposphere upon radio communications and implications for weather measurement
… aim of this research is to use observations of Very High Frequency (VHF) radio wave propagation to estimate the refractive index of air over a propagation path and subsequently the pressure, temperature, and water vapour. This can be accomplished by transmitting a known signal from one spatial …
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Large Signal HBT Model and Integrated Circuit Design Using 300-Ghz Indium Phosphide HBT Technology
… circuits. Good fitting to the measured DC and high-frequency data from single HBTs is achieved. In terms of circuit verification, high-gain and wideband variable gain amplifier (VGA) is developed using a negative-RE approach. This circuit shows a single-ended S21 of 18 dB and a 3-dB bandwidth …
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Cell modulated DC/DC converter
A very high frequency converter roughly based on a class E topology is investigated for replacing a conventional boost converter circuit. The loss mechanisms in class E inverters are characterized, and metrics are developed to aid in device selection for high frequency converter. A (30 MHz) …
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A concept for wildlife tracking using ultra high frequency (UHF) radio
… animals. Normally, a radio tracking using a low frequency between 30MHz to 300MHz known as Very High Frequency (VHF). In this study, a band of Ultra High Frequency (UHF) with a frequency 315MHz is used as a transmitter. While a encoder HT12E is used as a function of generate a data signal to the …
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Nitrogen environment, ecophysiology and growth of Gracilaria gracilus in Saldanha Bay, South Africa
… freshly collected material provided up to 30 % higher relative growth rates than seaweed maintained on the netlons for three successive months. Initial seedstock length greatly affected growth rate and yield such that 30 cm thalli fragments resulted in growth rates 14 % higher than for 10 cm …
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Comparison of positive and negative cloud-to-ground lightning dominant storms in three regions of the United States
… contiguous United States. Regions included the High Plains (eastern Colorado/western Kansas), central Oklahoma, and northern Alabama. Dual-polarization radar, lightning mapping array observations, and environmental reanalysis data were ingested by CLEAR to objectively assign lightning and …
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Full Bridge LLC Converter Secondary Architecture Study for Photovoltaic Application
… the main power stage and the key components with frequency consideration. The hardware circuit achieved the designed function while the overall hardware efficiency result agrees with analysis. In the implementation, the transformer is costume built for the system pacification. Another part is the …
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