• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 24
  • 5
  • 5
  • 5
  • 5
  • 2
  • 1
  • 1
  • Tagged with
  • 56
  • 19
  • 10
  • 10
  • 10
  • 9
  • 9
  • 8
  • 8
  • 8
  • 8
  • 8
  • 7
  • 7
  • 7
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

A Study of Switched Mode Power Amplifiers using LDMOS

Al Tanany, Ahmed January 2007 (has links)
<p>This work focuses on different kinds of Switch Mode Power Amplifiers (SMPAs) using LDMOS technologies. It involves a literature study of different SMPA concepts. Choosing the suitable class that achieves the high efficiency was the base stone of this</p><p>work. A push-pull class J power amplifier (PA) was designed with an integrated LC resonator inside the package using the bondwires and die capacitances. Analysis and motivation of the chosen class is included. Designing the suitable Input/Output printed circuit board (PCB) external circuits (i.e.; BALUN circuit, Matching network and DC</p><p>bias network) was part of the work. This work is done by ADS simulation and showed a simulated result of about 70% drain efficiency for 34 W output power and 16 dB gain at 2.14 GHz. Study of the losses in each part of the design elements is also included.</p><p>Another design at lower frequency (i.e.; at 0.94 GHz) was also simulated and compared to the previous design. The drain efficiency was 83% for 32 W output power and 15.4 dB Gain.</p>
12

THE STUDY AND IMPLEMENTATION OF MEANDER-LINE ANTENNA FOR AN INTEGRATED TRANSCEIVER DESIGN

Deng, Kai, Ma, Minjie January 2010 (has links)
This thesis focuses on the design and evaluation of the meander-line antenna geometry. One standard meander-line antenna and other two non-standard meander antennas have been studied. These printed antennas are discussed with the goal of identifying which is suitable for use in a miniaturized wireless transceiver design and which is able to provide the better performance using minimal Printed Circuit Board (PCB) space. In a word, the main objective is to characterize tradeoffs and identify which antenna provides the best compromise among volume, bandwidth and efficiency. The performance of each antenna is evaluated based on return loss, operational bandwidth, and radiation pattern characteristics. During our measurement, return loss is measured by reading the S11-port reflection coefficient on Vector Network Analyzer (VNA). This coefficient can be used to characterize how well the antenna is able to be efficiently fed. Operational bandwidth is measured as the frequency range over which the antenna keeps the value of Voltage Standing Wave Ratio (VSWR) or equivalently has -10dB return loss. Ansoft High Frequency Structure Simulator (HFSS) is used to simulate expected characteristics which are resonant frequency, bandwidth, VSWR, and radiation pattern. HFSS is used to provide a good guide for the antenna design before the actual prototype is manufactured. Simulated results are compared with results of measurement to point out the differences and help demonstrate the practical effects on antenna performance. Radiation pattern are measured to illustrate the effects of antenna miniaturization. All the above measurements are done in the anechoic chamber.
13

Development of a Balun with Suspending Structure by MEMS Technology

Deng, Yu-Ting 16 November 2011 (has links)
Balun is a key component in radio frequency (RF) circuits. The conventional Si-based planar spiral balun presented a high insertion loss. To solve this problem, this thesis firstly develops a Si-based suspending spiral balun using electrochemical deposition and surface micromachining technology for the fourth generation of wireless communication system. To reduce the power dissipation of the conventional Si-based planar spiral balun, thesis utilized a suspending structure to reduce the power loss through the substrate and dielectric layer. The fabricated suspending spiral balun are constructed by three bottom GSG electrodes, thirty three supporting copper vias and a suspending spiral copper conducting layer. The main fabrication processes in this research including: (1) four thin-film deposition processes, (2) four photolithography processes, (3) two etching processes and (4) two copper electroplating processes. In addition, this thesis used the commercial software (Ansoft HFSS) to analysis the high frequency characteristic of Si-based suspending spiral balun. The finished Si-based suspending spiral balun were measured by a commercial network analyzer under 2~8 GHz testing frequency range. Based on the measurement results, the value of insertion loss is 1.26 dB at 5.2 GHz, magnitude imbalanced is lower than 0.86 dB, phase imbalanced is less than 3.4 degree and CMRR is more than 30 dB. Finally, this thesis successfully develops a Si-based suspending spiral balun using MEMS technology for the fourth generation wireless communication system.
14

A Study of Switched Mode Power Amplifiers using LDMOS

Al Tanany, Ahmed January 2007 (has links)
This work focuses on different kinds of Switch Mode Power Amplifiers (SMPAs) using LDMOS technologies. It involves a literature study of different SMPA concepts. Choosing the suitable class that achieves the high efficiency was the base stone of this work. A push-pull class J power amplifier (PA) was designed with an integrated LC resonator inside the package using the bondwires and die capacitances. Analysis and motivation of the chosen class is included. Designing the suitable Input/Output printed circuit board (PCB) external circuits (i.e.; BALUN circuit, Matching network and DC bias network) was part of the work. This work is done by ADS simulation and showed a simulated result of about 70% drain efficiency for 34 W output power and 16 dB gain at 2.14 GHz. Study of the losses in each part of the design elements is also included. Another design at lower frequency (i.e.; at 0.94 GHz) was also simulated and compared to the previous design. The drain efficiency was 83% for 32 W output power and 15.4 dB Gain.
15

CMOS bulk-driven mixers with passive baluns

Van Vorst, Daryl 11 1900 (has links)
The design, simulation, and measurement of two bulk-driven down-conversion mixers with on-chip transformer baluns in 0.18 μm CMOS is presented. Applying either the RF signal or the local oscillator (LO) signal to the bulk connection of the transistors allows the amplification and switching stages of a conventional mixer to be combined into a single stage, thus improving the voltage headroom of the mixer. The addition of a transformer balun to the mixers improves the input impedance match, provides passive voltage gain, and performs single-ended to balanced conversion. A semi-analytical power-series analysis of the mixers is also presented. The mixer in which the RF signal is applied to the gates of the mixing transistors achieves a measured input-referred 1-dB compression point (P1dB) of −14 dBm, an input-referred third-order intercept point (IIP3) of −5.2 dBm, a gain of 13.6 dB, a noise figure (NF) of 26 dB, and an LO-to-RF isolation of 50 dB. The overall performance of both mixers is found to be comparable with other CMOS mixers, but with a higher noise figure (which can be mitigated with a high gain low-noise amplifier (LNA)).
16

CMOS bulk-driven mixers with passive baluns

Van Vorst, Daryl 11 1900 (has links)
The design, simulation, and measurement of two bulk-driven down-conversion mixers with on-chip transformer baluns in 0.18 μm CMOS is presented. Applying either the RF signal or the local oscillator (LO) signal to the bulk connection of the transistors allows the amplification and switching stages of a conventional mixer to be combined into a single stage, thus improving the voltage headroom of the mixer. The addition of a transformer balun to the mixers improves the input impedance match, provides passive voltage gain, and performs single-ended to balanced conversion. A semi-analytical power-series analysis of the mixers is also presented. The mixer in which the RF signal is applied to the gates of the mixing transistors achieves a measured input-referred 1-dB compression point (P1dB) of −14 dBm, an input-referred third-order intercept point (IIP3) of −5.2 dBm, a gain of 13.6 dB, a noise figure (NF) of 26 dB, and an LO-to-RF isolation of 50 dB. The overall performance of both mixers is found to be comparable with other CMOS mixers, but with a higher noise figure (which can be mitigated with a high gain low-noise amplifier (LNA)).
17

CMOS bulk-driven mixers with passive baluns

Van Vorst, Daryl 11 1900 (has links)
The design, simulation, and measurement of two bulk-driven down-conversion mixers with on-chip transformer baluns in 0.18 μm CMOS is presented. Applying either the RF signal or the local oscillator (LO) signal to the bulk connection of the transistors allows the amplification and switching stages of a conventional mixer to be combined into a single stage, thus improving the voltage headroom of the mixer. The addition of a transformer balun to the mixers improves the input impedance match, provides passive voltage gain, and performs single-ended to balanced conversion. A semi-analytical power-series analysis of the mixers is also presented. The mixer in which the RF signal is applied to the gates of the mixing transistors achieves a measured input-referred 1-dB compression point (P1dB) of −14 dBm, an input-referred third-order intercept point (IIP3) of −5.2 dBm, a gain of 13.6 dB, a noise figure (NF) of 26 dB, and an LO-to-RF isolation of 50 dB. The overall performance of both mixers is found to be comparable with other CMOS mixers, but with a higher noise figure (which can be mitigated with a high gain low-noise amplifier (LNA)). / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate
18

Compact and broadband antenna system at UHF

Riauka, Nerijus January 2010 (has links)
The aim of this research was to study a novel, broadband, low cost, low profile and a high-medium gain antenna in the UHF band. This has been achieved through numerical modelling, theoretical investigation and physical measurements. In this study two commercially available antenna systems are investigated in order to compare and establish potential deficiencies in the UHF antenna systems. A number of disadvantages are resolved within a novel antenna system design. The parametric study is performed for each element of the novel antenna system in order to optimise its overall performance. The indoor and outdoor measurements have been carried out in house, in order to validate the predicted results. The novel antenna system is compared to the most popular and commercially available UHF antenna systems. The study demonstrates that the novel antenna system has clear advantages such as broadband, balanced, compact and low cost when compared to the commercial antenna designs studied here. The comparison of the manufacturers' data to the measured results shows a good match, validating the outdoor measurements technique used in this research.
19

Širokopásmová sinusová anténa s dvojí polarizací / Wideband Sinuous Antenna with Dual Polarization

Haloda, Jiří January 2012 (has links)
This paper deals with sinuous broadband antenna, witch operating frequency 1 to 6 GHz. The antenna parameters, which change their physical dimension were shown in this paper. Antenna structure is planar and feeding network line have to be planar too. There are different ways to describe and construct from unbalanced to balanced line by baluns. There are also design impedance transform to match antenna in this paper. The simulation and measured results are showen the antenna has wideband character.
20

Conception et réalisation de fonctions millimétriques en technologie BiCMOS 55nm / Design and realization of millimeter wave circuits in advanced BiCMOS 55nm technology

Serhan, Ayssar 28 September 2015 (has links)
Au cours des dernières années, la faisabilité des émetteurs-récepteurs millimétriques entièrement intégrés a été largement démontrée en technologies silicium CMOS et BiCMOS. Deux axes sont actuellement très porteurs dans ce domaine : (1) l’amélioration des performances à travers des boucles d’asservissement intégrées (ALC : Automatique Level Control), (2) le développement de solutions de caractérisation sur silicium des composants millimétriques (BIT : Built In Test). L’objectif principal de cette thèse est de développer les blocsde base (détecteurs de puissance et baluns) pour répondre aux besoins actuels des applications ALC et BIT. Les circuits réalisés combinent l’avantage de composants actifs de la technologie BiCMOS 55 nm, de STMicroelectronics, avec l’avantage des structures passives à ondes lentes développées à l’IMEP-LAHC. Ce travail permet un développement plus rapide et robuste pour la future génération de systèmes millimétriques. / In the past few years, the feasibility of high performance millimeter-wave(mmWave) fully-integrated transceivers has been widely demonstrated in both CMOS andBiCMOS silicon technologies. Nowadays, automatic level control (ALC) solutions and in-situtesting (BIT: Built in Testing) and characterization of mmWave components, constitute themajor research interest in mmWave domain. This work focus on the development of the mainbuilding blocks (power detectors and baluns) that meet the requirement of the today’smmWave ALC and BIT applications. The developed prototypes take advantage of the highperformances transistors offered by the BiCMOS 55 nm technology, from STMicroelectronics, aswell as the high performances of the slow-wave based passive components developed by theIMEP-LAHC laboratory. Several prototypes were developed as a proof of concept for thedesignated applications. This work helps future generation millimeter-wave systems to havefaster development and better robustness.

Page generated in 0.026 seconds