• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 5
  • 1
  • Tagged with
  • 6
  • 6
  • 6
  • 6
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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.
1

Subharmonic Mixers in CMOS Microwave Integrated Circuits

Jackson, Bradley 25 March 2009 (has links)
This thesis explores the design and applications of subharmonic mixers in CMOS microwave integrated circuits. First, a 2x down-converting subharmonic mixer is demonstrated with a measured conversion gain of 8 dB using a 2.1 GHz RF signal. Extending the concept of the 2x subharmonic mixer, a 4x subharmonic mixer is proposed that operates in the 12 GHz Ku-band. This circuit is the first 4x subharmonic mixer in CMOS, and achieves a 6 dB conversion gain, which is the highest for any 4x subharmonic mixer regardless of circuit topology or fabrication technology. Furthermore, it achieves very high measured isolation between its ports (e.g. 4LO-RF: 59 dB). Since both the 2x and the 4x subharmonic mixers require a quadrature oscillator, a new oscillator circuit is presented that could be used with either of the aforementioned mixers. This quadrature oscillator uses active superharmonic coupling to establish the quadrature fundamental relationship. The oscillation frequency is 3.0 GHz and the measured output power is -6 dBm. A dual-band mixer/oscillator is also demonstrated that can operate as either a fundamental mixer or a subharmonic mixer depending on a control voltage. This circuit operates from 5.0 GHz to 6.0 GHz or from 9.8 GHz to 11.8 GHz by using either the fundamental output or the second harmonic output of the quadrature oscillator circuit described above and achieves conversion gain over both frequency bands. A novel frequency tripler circuit is presented based on a subharmonic mixer. This circuit uses the 2x subharmonic mixer discussed above, along with a feedforward fundamental cancellation circuit. The measured fundamental suppression is up to 30 dB and the conversion gain is up to 3 dB. Finally, a frequency divider circuit based on a subharmonic mixer is presented that divides the input signal frequency by a factor of three. This circuit uses a single-balanced version of the 2x subharmonic mixer described above in a regenerative divider topology. The measured input signal bandwidth is 300 MHz (5.2 GHz to 5.5 GHz) with an input power of -7 dBm and the maximum conversion gain is 0 dB. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2009-03-24 16:08:31.805
2

Low-Noise Mixing Circuits in CMOS Microwave Integrated Circuits

HO, STANLEY 25 August 2009 (has links)
In this thesis, three low-noise active mixing circuits are presented in CMOS technology. Mixers can be found at the front-end of almost every communication systems. However, despite many advantages the active mixers have, one drawback is their poor noise performance. One mixer that has been widely used in integrated circuit is the Gilbert cell. This thesis demonstrated that by merging the low-noise amplifier (LNA) with the Gilbert cell, a low-noise active mixer can be realized. This kind of mixer relaxes the front-end design, allows higher circuit integration, and reduces power consumption. The first circuit is a narrowband low-noise mixer that operates at 5.4 GHz in 0.18 um CMOS. An inductive degenerated LNA is used as the transconductor. Together with a current bleeding circuit, a gain of 13.1 dB and a low 7.8 dB single-sideband noise figure are achieved. The circuit was fabricated and measured. Simulation and measurement results are compared and discussed. The second circuit is a broadband low-noise mixer that operates between 1 and 5.5 GHz in 0.13 um CMOS. The noise-cancelling technique is used to design the transconductors. This technique does not require the use of inductors while able to achieve a sub 3 dB noise figure and input matching over a large bandwidth. To further extend the mixer bandwidth, the series inductive peaking was used. Measured and simulated results showed great agreement. It has a high gain of 17.5 dB, a bandwidth of 4.5 GHz, and a low average double-sideband noise figure of 3.9 dB. This mixer has the best broadband noise performance ever reported in CMOS. Finally, a double-balanced low-noise self-oscillating mixer (SOM) in 0.13 um CMOS is presented. This is a current-reuse, highly integrated circuit that combines an LNA, mixer, and oscillator seamlessly into a single component. The oscillator generates the required LO while serving as the mixer load simultaneously. Measured and simulated results showed excellent agreement. A low double-sideband noise figure of 4.4 dB and a gain of 11.6 dB were measured. This type of SOM and loading structure are the first ever reported. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2009-08-23 12:41:20.445
3

Pulsed RF Circuits for Ultra Wideband Communications and Radar Applications

El-Gabaly, AHMED 23 August 2011 (has links)
This thesis explores the design of fast-settling pulse generators and pulsed low noise amplifiers (LNAs) for Ultra-Wideband (UWB) applications. These components are critical in pulsed UWB transceivers, and a high energy efficiency is sought without adversely affecting RF performance and functionality. To this end, new pulse generators with a subnanosecond settling time and a low energy consumption of only a few picojoules per pulse are targeted. Moreover, a novel pulsed LNA is investigated for a low power consumption that can be scaled with the duty cycle. First, an energy-efficient tunable pulse generator is proposed for high-data-rate 3.1-10.6 GHz UWB applications. A current-starved ring oscillator is quickly switched on and off, and the amplitude envelope is shaped using a passive attenuator. The energy consumption per pulse is below 4.2 pJ while the pulse amplitude is 150 mV, yielding a high energy efficiency. A quadrature pulse generator is then presented for 22-29 GHz UWB applications with a settling time below 0.5 ns. An inductor-capacitor (LC) oscillator is quickly switched on and off with a new technique, and the amplitude envelope is shaped using a variable passive attenuator. The energy consumption per pulse is only 6.2 pJ, and the pulse amplitude is more than 240 mV, yielding the highest energy efficiency reported to date in CMOS. Next, a 3-10 GHz pulsed ring oscillator that offers direct quadrature phase modulation is demonstrated. Current impulses are injected into the oscillator to enable fast startup and implement quadrature phase modulation. The energy consumption and voltage swing varies from 13 pJ and 300 mV at 3 GHz to 18 pJ and 200 mV at 10 GHz respectively, yielding a high energy efficiency. Lastly, a fast switching noise cancelling LNA is proposed for 3.1-10.6 GHz UWB applications that settles within 1.3 ns for switching speeds as high as 200 MHz. Inductive peaking is introduced in the noise cancelling topology to achieve a sub-4dB flat noise figure and a high gain of 16.6 dB for frequencies up to 10 GHz. The average power consumption is also below 10 mW with a 50% duty cycle clock. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2011-08-23 15:29:58.93
4

Integrated Antennas : Monolithic and Hybrid Approaches

Öjefors, Erik January 2006 (has links)
<p>This thesis considers integration of antennas and active electronics manufactured on the same substrate. The main topic is on-chip antennas for commercial silicon processes, but hybrid integration using printed circuit board technology is also addressed.</p><p>The possible use of micromachining techniques as a means of reducing substrate losses of antennas manufactured on low resistivity silicon wafers is investigated. Compact dipole, loop, and inverted-F antennas for the 20-40 GHz frequency range are designed, implemented, and characterized. The results show significantly improved antenna efficiency when micromachining is used as a post-processing step for on-chip antennas manufactured in silicon technology.</p><p>High resistivity wafers are used in a commercial silicon germanium technology to improve the efficiency of dipole antennas realized using the available circuit metal layers in the process. Monolithically integrated 24 GHz receivers with on-chip antennas are designed and evaluated with regard to antenna and system performance. No noticeable degradation of the receiver performance caused by cross talk between the antenna and the integrated circuit is observed.</p><p>For low frequency antenna arrays, such as base station antennas, hybrid integration of active devices within the antenna aperture is treated. A compact varactor based phase shifter for traveling wave antenna applications is proposed and evaluated. Electrically steerable traveling wave patch antenna arrays, with the phase shifters implemented in the same conductor layer as the radiating elements, are designed and manufactured in microstrip technology. It is experimentally verified that the radiation from the feed network and phase shifters in the proposed antenna configuration is small.</p>
5

Integrated Antennas : Monolithic and Hybrid Approaches

Öjefors, Erik January 2006 (has links)
This thesis considers integration of antennas and active electronics manufactured on the same substrate. The main topic is on-chip antennas for commercial silicon processes, but hybrid integration using printed circuit board technology is also addressed. The possible use of micromachining techniques as a means of reducing substrate losses of antennas manufactured on low resistivity silicon wafers is investigated. Compact dipole, loop, and inverted-F antennas for the 20-40 GHz frequency range are designed, implemented, and characterized. The results show significantly improved antenna efficiency when micromachining is used as a post-processing step for on-chip antennas manufactured in silicon technology. High resistivity wafers are used in a commercial silicon germanium technology to improve the efficiency of dipole antennas realized using the available circuit metal layers in the process. Monolithically integrated 24 GHz receivers with on-chip antennas are designed and evaluated with regard to antenna and system performance. No noticeable degradation of the receiver performance caused by cross talk between the antenna and the integrated circuit is observed. For low frequency antenna arrays, such as base station antennas, hybrid integration of active devices within the antenna aperture is treated. A compact varactor based phase shifter for traveling wave antenna applications is proposed and evaluated. Electrically steerable traveling wave patch antenna arrays, with the phase shifters implemented in the same conductor layer as the radiating elements, are designed and manufactured in microstrip technology. It is experimentally verified that the radiation from the feed network and phase shifters in the proposed antenna configuration is small.
6

Amplificadores de banda ancha y bajo ruido basados en tecnología de GaAs para aplicaciones de radiometría

Aja Abelán, Beatriz 19 January 2007 (has links)
En esta Tesis se ha realizado análisis, diseño y caracterización de los amplificadores de bajoruido y banda ancha en tecnología de GaAs PHEMT con aplicación a los módulos posteriores delradiómetro del instrumento de baja frecuencia del satélite Planck. La Tesis se compone de las siguientes partes:- Introducción y estudio del funcionamiento del radiómetro del instrumento de baja frecuencia de Planck.- Diseño y caracterización de amplificadores de bajo ruido utilizando tecnología de GaAs. Se presentan diseños MMIC en la banda Ka y en la banda Q, y un diseño MIC en la banda Q.- Diseño y construcción de los módulos posteriores en las bandas de 30 y 44 GHz. Se presentan varios prototipos fabricados en ambas bandas, así como medidas de cada uno de los subsistemas que los forman.- Desarrollo de técnicas de medida para receptores de banda ancha con detección directa y su aplicación a la caracterización de los módulos posteriores, mostrando el funcionamiento de los prototipos representativos para las dos bandas de frecuencia.- Integración de los módulos posteriores con los módulos frontales y presentación de algunos de los resultados de medida de los radiómetros completos. / This Thesis deals with the analysis, design and characterization of broadband low noise amplifiersin GaAs PHEMT technology with application to the radiometer Back-End Modules for the Planck Low Frequency Instrument (LFI). The Thesis is composed of the next parts:- Introduction and study about the radiometer of the Planck low frequency instrument.- Design and characterization of low noise amplifiers using GaAs technology. Ka-band MMIC designs and Q-band MMIC and a MIC design are presented.- Design and assembly of the 30 and 44 GHz back-end modules. Several prototypes have been manufactured in both frequency bands and the most representative test results of each subsystem are presented.- Development of measurement techniques for broadband direct detection receivers and their application to the characterization of the back-end modules. Performance of representative prototypes in both frequency bands is included.- Integration of the back end modules and front end modules and significant results of the tests for a radiometer in each frequency band.

Page generated in 0.0649 seconds