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 “"Cut-off Frequency"”.
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Modeling and Characterization of Heterojunction Bipolar Transistors
Heterojunction bipolar transistor (HBTs) offer several advantages over their homo-junction counterparts resulting from the use of semiconductors in the emitter and base with different bandgaps. These advantages include high current gain, large cut-off frequency and short gate delay in digital logic …
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Phononic materials as ultrasonic filters in nondestructive evaluation measurements
… phononic materials can be engineered to induce frequency regions of reduced transmission, called band gaps. This work presents a method to use phononic materials as ultrasonic filters in nonlinear ultrasound measurements, to passively filter extraneous nonlinearities present in experiments. …
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Longitudinal impedance of a prototype kicker magnet system
… The measurement was performed in two frequency ranges. From 0.3 to 50 MHz the magnet was transformed into a 50 Ω coaxial line, and from 45 to 200 MHz into a 180 Ω coaxial line. TSD calibration of the measurement assembly was performed in the higher frequency range while HP calibration …
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Integrated Frequency-Selective Conduction Transmission-Line EMI Filter
… simulation tool are used to analyze the high-frequency attenuator and the DM transmission-line EMI filter. The insertion gain, transfer gain, current distribution, and input impedance of the filter under a nominal design are discussed. In order to apply the transmission-line EMI filter to …
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Low Power Adaptive Circuits: An Adaptive Log Domain Filter and A Low Power Temperature Insensitive Oscillator Applied in Smart Dust Radio
… circuits. One is an adaptive filter at audio frequency for system identification. The other is a temperature insensitive oscillator for low power radio frequency communication. The adaptive filter is presented with integrated learning rules for model reference estimation. The system is a first …
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Frequency Domain Conductive Electromagnetic Interference Modeling and Prediction with Parasitics Extraction for Inverters
… of data. The proposed approach is to use the frequency-domain analysis technique that computes the EMI spectrum directly by decomposing noise sources and their propagation paths. This method not only largely reduces the computational effort, but also provides the insightful information about …
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DC and AC modeling of heterostructure bipolar transistors (HBTS)
… current, the ac current gain as a function of frequency, and finally the unity current gain cut-off frequency as a function of the collector current are calculated for various graded and abrupt, single and double AlGaAs/GaAs HBTs. The results are in good agreement with the reported data.
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A compact transport and charge model for GaN-based high electron mobility transistors for RF applications
… devices. Using the model, a projection of cut-off frequency (f-[tau]) of GaN-based HEMTs with scaling is performed to highlight performance bottlenecks.
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Bandpass filter design with spurious frequency reduction capability
… undesired pass band at twice the design central frequency of the filter. The narrowband with spurious suppression is achieved by using two stage PCMBF, BPF was designed by replacing the tight couplers are arranged at the input and output of the filter whist the weak couplers at the middle section …
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Extracting Polar Anisotropy Parameters from Seismic Data
… conventional procedure, but then filtered it in frequency domain using a cut-off frequency to be determined empirically. The low-frequency part of the normalization function was used to eliminate the propagation factors in the real data, but not the reflection coefficients. After scaling, the …
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Tunable microwave filters using ferroelectric thin films
Frequency agile microwave devices based on Barium Strontium Titanate (BST) thin films have gained a lot of interest in recent years. The frequency agility of the ferroelectric devices is based on the external DC electric field controlled permittivity of BST thin film. In this research work, several …
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Sampling based on local bandwidth
… is shown to decrease with the variation in the cut-off frequency of the filter. In the second part of the thesis, a definition for local bandwidth based on the time-warping of globally bandlimited signals is reviewed. Using this definition, a method is developed for sampling and reconstructing …
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Elasticity Measurement at High Temperatures
… a temperature of 1000°C. Tables of a nomialised frequency parameter for thin discs are given covering the ranges of Poisson's Ratio -0.5 to +0.5 in steps of 0.01 to enable the calculation of Poisson's Ratio and Young's modulus from the thin disc resonant frequencies. The delay line technique was …
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Finite Element Method Modeling Of Advanced Electronic Devices
… transconductance and gate capacitance on the frequency, are explored. The validity of the widely used quasi-static approximation is examined. The results show that the quasi-static approximation overestimates the transconductance and gate capacitance at high frequencies, but gives a more …
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INFRARED SENSORS USING SILICON MICROSTRUCTURES
… of 2 µm. The responsivity is 10 V/W with a cut-off frequency of 400 Hz.
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Technology and characterization of GaN-based heterostructure field effect transistors (HFETs)
… efficiency of 2 W/mm and 26%, respectively, at a frequency of 2.14 GHz. The gate leackage currents, which were increased after depositing the passivation layer, could be reduced by using a thin insulating layer inserted between the gate metal and the barrier layer. These so called metal-insulator …
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Numerical evaluation of wavenumbers of the acoustic waves propagating in an ice-covered ocean
… of the eigenvalues with respect to the frequency, the monotonicity of the eigenvalues with respect to the frequency, and the existence of the cut-off frequency. We compare these eigenvalues with the eigenvalues for the case of a waveguide with a free surface. To obtain some information …
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Design of digital differentiators
… rejecting noise frequencies higher than the cut-off frequency. Both steady-state frequency-domain characteristics and Time-domain analyses are given for the proposed differentiators. It is shown that the proposed differentiators perform well when compared to previously proposed filters. When …
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Active control of coupled wave propagation in fluid-filled elastic cylindrical shells
… the control performance below the first acoustic cut-off frequency and decreases it above this frequency.
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Nonlinear Acoustic Waves Generated by Surface Disturbances and Their Effect on Lower Thermospheric Composition
… vertically propagating acoustic waves near the cut-off frequency, and for simulations of steepening waves at finite spatial resolution. The addition of a mass fraction density introduces noticeable fluctuations to the state of the atmosphere that can account for modulation of acoustic waves. The …
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