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 57 for “"Zero crossing"”.
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Zero Crossing Based Spectral Analysis
This dissertation contains a study of the timed zeros, both real and complex, of a band-limited signal. Mathematics essential to the study is explained and the method of using a simple invertible transform to convert complex zeros to real zeros, otherwise known as zero crossings, is considered. The …
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A zero-crossing switched-capacitor filter design
… switched-capacitor (CBSC) circuits and zero-crossing based circuits (ZCBC) were suggested as a possible solution to the op-amp based circuits. In this thesis, we explore zero-crossing based circuits (ZCBC) in high-order differential switched-capacitor filters to replace area inefficient …
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High performance zero-crossing based pipelined analog-to-digtal converters
… op-amps in pipelined ADCs are replaced with zero-crossing detectors(ZCD). Without the closed-loop feedback provided by the op-amp, a new set of design constraints for Zero-Crossing Based Circuits (ZCBC) is explored.
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A time-interleaved Zero-Crossing-Based analog-to-digital converter
… which has been hindered by op-amp limitations. Zero Crossing Based (ZCB) switched-capacitor topologies have been proposed as an alternative to op-amp based circuits because ZCB circuits do not suffer from the same CMOS scaling issues. This research applies ZCB techniques to Time Interleaved ADCs …
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A high performance zero-crossing based pipelined analog-to-digital converter
In this thesis, I describe a zero-crossing based pipelined ADC. Unlike traditional pipelined ADCs, this work does not use any op-amps in the signal path. The use of zero-crossing based circuits made it possible to achieve a much better figure of merit. The ADC is design to operate at 200MS/s with a …
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Study on Zero Crossing Detection in CRM Totem-pole PFC Converter
… totem-pole PFCs has become popular for achieving zero-voltage switching (ZVS). This enables pushing the converter's switching frequency into the megahertz range to achieve high power density while maintaining high efficiency. Zero-crossing detection (ZCD) of inductor current is important for …
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A low-voltage zero-crossing-based delta-sigma analog-to-digital converter
A zero-crossing-based (ZCB) switched-capacitor technique is presented for operation under low power supply voltages without gate boosting. Voltage ramp generators maintain common-mode level at each integrator output. Correlated level-shifting is used to increase the effective output impedance of …
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A zero-crossing based pipelined analog-to-digital converter with supply voltage scalibility
A zero-crossing based pipelined analog-to-digital converter (ADC) has been designed and is fabricated in a 65nm CMOS process. The highly digital implementation characteristic of the zero-crossing detection technique enables energy efficient operation and voltage scaling. Supply voltage scaling …
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Vibration detection in turbomachinery using non-contacting sensors
… the ECS signature, signal magnitude and signal zero crossing time. The signal magnitude is used to find tip clearance, and the zero crossing time is used to estimate vibrational parameters over the course of multiple revolutions. These techniques fail to exploit the majority of the information …
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Linear Operation of Switch-Mode Outphasing Power Amplifiers
… techniques however non-linear effects around the zero crossing point are not. As a result signal processing techniques for suppressing and avoiding non-linear operation in low power regions are explored. A novel method of digital pre-distortion is presented, and conventional techniques for …
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Asymptotic analysis of mass-dominated convection in a nanofluid
… particle radius is an inverted parabola with two zero crossings. The first zero crossing occurs near zero particle radius. The second zero crossing occurs at larger size particle radius, although still in the nanosize range.
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Techniques for low-power high-performance ADCs
… The first design is a voltage scalable zero-crossing based pipelined ADC. The zero-crossing based circuit technique is modified and optimized to improve the limited ADC resolution in nano-scaled CMOS technology. The proposed unidirectional charge transfer scheme allows faster and more …
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Cascade Dual-Buck Inverters for Renewable Energy and Distributed Generation
… it theoretically eliminates the inherent current zero-crossing distortion of the single-unit dual-buck type inverter. In addition, phase-shift control can greatly reduce the ripple current or cut down the size of passive components by increasing the equivalent switching frequency. An asymmetrical …
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A Study on High-Speed Magnetic Induction Tomography Instrumentation Aiming at Low Conductivity Applications
… MIT systems operating at 10 MHz based on the zero crossing phase measurement technique were developed and implemented.The eight channel Cardiff Mk2c aimed at the multiphase flow in oil pipes. The Cardiff Mk2c achieved a frame rate of 12.5 frames per second making it the fastest 10 MHz …
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Low level and intermediate level vision in aerial images
… selection are used in Haralick's directional zero-crossing edge operator resulting in improved performance. Finally, a graytone corner detector with significantly better probability of correct corner assignment than other corner detectors available in the literature. Intermediate-level modules …
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Reactive power support capability of flyback microinverter with pseudo-dc link
… circuit is proposed to effectively mitigate zero crossing distortion. Simulations and experimental results are provided to support the theoretical propositions.
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Design and analysis of reconfigurable analog system
… for 40% of the total noise power and the zero-crossing detector is responsible for 60%. The chip is tested in two different filter configurations. In one test, the first two stages of the chip are configured as a second order Butterworth filter and the third stage is configured as an …
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Synthesis and evaluation of rare-earth doped glasses and crystals for optical refrigeration
… of ~7 mK and enabled precise measurement of the zero-crossing temperature and net quantum efficiency. Several Yb3+-doped ZBLANI glasses fabricated from precursors of varying purity and by different processes were analyzed in detail by TBDLT. Laser-induced cooling was observed at room temperature …
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Doppler spread estimation in mobile fading channels
… dissertation, first the performance of classical crossing- and covariance-based speed estimators is studied. Next, the problem of mobile speed estimation using diversity combining is investigated. Then, a nonparametric estimation technique is proposed that is robust to different channel …
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Investigating DC circuit breaker service life
… Unlike AC systems, DC lacks a natural zero-crossing which results in large transient voltages that accelerate switch wear and reduce service life. A low-cost low-complexity RC circuit was designed using fundamental component equations and implemented in Simulink and in hardware …
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