This thesis describes the design of a baseband digital predistortion architecture for radio frequency (RF) amplifier linearization. Existing amplifier linearization techniques are first examined. The nonlinearity of an amplifier can be characterized as amplitude-to-amplitude distortion and amplitude-to-phase distortion. The distortion can be corrected by providing a predistorted driver signal (both in amplitude and phase) to the amplifier. This counteracts the nonlinearity of the amplifier so that the overall system is more linear. A pipelined predistortion architecture is designed to allow fast processing speed, and is capable of providing linearization for a bandwidth of 25 Mhz. The simulation results show significant improvement in amplifier's performance using predistortion technique. The system bandwidth versus cost is examined by using commercially available components. / Graduation date: 1996

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 146-149).

This thesis is concerned with the design and implementation of radio frequency (RF) power amplifiers and micro-electromechanical systems---namely MEMS varactors. This is driven by the many wireless communication systems which are constantly moving towards increased integration, better signal quality, and longer battery life. / The power amplifier consumes most of the power in a receiver/transmitter system (transceiver), and its output signal is directly transmitted by the antenna without further modification. Thus, optimizing the PA for low power consumption, increased linearity, and compact integration is highly desirable. / Micro-electromechanical systems enable new levels of performance in radio-frequency integrated circuits, which are not readily available via conventional IC technologies. They are good candidates to replace lossy, low Q-factor off-chip components, which have traditionally been used to implement matching networks or output resonator tanks in class AB, class F, or class E power amplifiers. The MEMS technologies also make possible the use of new architectures, with the possibility of flexible re-configurability and tunability for multi-band and/or multi-standard applications. / The major effort of this thesis is focused on the design and fabrication of an RF frequency class AB power amplifier in the SiGe BiCMOS 5HP technology, with the capability of being tuned with external MEMS varactors. The latter necessitated the exploration of wide-tuning range MEMS variable capacitors, with prototypes designed and fabricated in the Metal-MUMPS process. / An attempt is made to integrate the power amplifier chip and the MEMS die in the same package to provide active tuning of the power amplifier matching network, in order to keep the efficiency of the PA constant for different input power levels and load conditions. / Detailed simulation and measurement results for all circuits and MEMS devices are reported and discussed.

Thesis (M.S.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xix, 156 p.; also includes graphics (some col.). Includes bibliographical references (p. 152-156).

Thesis (M.E.)--University of Canterbury, 2008. / Typescript (photocopy). "August 2008." Includes bibliographical references (p. [123]-126). Also available via the World Wide Web.

Thesis (MScIng)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Modern communication systems demand efficient, linear power amplifiers. The amplifiers are often operated in the backed-off power levels at which linear amplifiers such as class B amplifier are particularly inefficient. The Doherty amplifier provides an improvement as it increases efficiency at backed of power levels. Doherty amplifiers consists of two amplifiers, a carrier amplifier and a peaking amplifier, of which the output is combined in a novel way. Implementation of the Doherty amplifier with transistors is not ideal. One of the main problems is the insufficient current production of the peaking amplifier at peak envelope power (PEP) if it is implemented as a class C amplifier. A suggested solution to this problem is a bias adaption system that controls the peaking amplifier gate voltage dynamically depending on the input power levels. The design and evaluation of such a adaptive Doherty amplifier is the main goal of this thesis. A classical Doherty amplifier with and an uneven Doherty amplifier with unequal power division between the carrier and peaking amplifiers are also evaluated and compared with the adaptive Doherty amplifier. The amplifiers are designed using a 10 W LDMOS FET device, the MRF282. The adaptive Doherty amplifier and the uneven Doherty amplifier show significant improvements in efficiency and output power over the even Doherty amplifier. At PEP the adaptive Doherty delivers 42.4 dBm at 39.75 % power added efficiency (PAE), the uneven Doherty amplifier 41.9 dBm at 40.75 % PAE and the even Doherty amplifier 40.8 dBm at 38.6 % PAE. At 3dB backed-off input power the adaptive Doherty amplifier has an efficiency of 34.3%, compared to 34.9 5% for the uneven Doherty amplifier and 29.75 % for the even Doherty amplifier. / AFRIKAANSE OPSOMMING: Moderne kommunikasie stelsels vereis effektiewe, linieêre drywing versterkers. Die versterkers word dikwels in laer drywings vlakke bedryf waar linieêre versterkers soos ’n klas B versterker besondere lae effektiwiteit het. Die Doherty versterker bied ’n uitweg omdat dit verbeterde effektiwiteit by lae drywings vlakke bied. ’n Doherty versterker bestaan uit twee versterkers, die hoof versterker en die aanvullende versterker, waarvan die uittrees met ’n spesiale kombinasie netwerk bymekaar gevoeg word. Die implementasie van Doherty versterkers met transistors is nie ideaal nie. Een van die hoof probleme is die onvoldoende stroom wat deur die aanvullings versterker gebied word by piek omhulsel drywing (POD). ’n Oplossing vir die probleem is om ’n aanpassings sisteem te gebruik wat die aanvullende versterker se hekspanning dinamies beheer afhangende van die intree drywings vlakke. Die ontwerp en evaluasie van so ’n aanpassings Doherty versterker is die hoof doel van hierdie tesis. ’n Klassieke Doherty versterke met gelyke drywings verdeling en ’n ongelyke Doherty versterker wat gebruik maak van ongelyke drywings verdeling tussen die hoof-en aanvullende versterkers is ook gevalueer en vergelyk met die aanpassings Doherty versterker. Die versterkers was ontwerp met ’n 10 W LDMOS FET, die MRF282. Die aanpassings Doherty versterker en die ongelyke Doherty versterker het aanmerklike verbeteringe in effektiwiteit en uittree drywing gebring in vergelyking met die ewe Doherty versterker. By POD het die aanpassings versterker 42.4 dBm teen 39.75 % drywing toegevoegde effektiwiteit (DTE) gelewer, die ongelyke Doherty versterker 41.9 dBm teen 40.75 % DTE, en die ewe Doherty versterker 40.8 dBm teen 38.6 DTE. By ’n intree drywingsvlak 3 dB laer as POD het die aanpassings Doherty versterker ’n effektiwiteit van 34.3 % getoon, in vergelyking met die onewe Doherty versterker se 34.9 % en die ewe Doherty versterker se 29.75 % DTE.

No description available.

<p> This thesis contributes to the computer-aided design (CAD) of spiral inductors and LC resonators with spiral inductors exploiting full-wave electromagnetic (EM) analysis.</p> <p> The spiral inductor is widely used in radio frequency integrated circuits (RF ICs), such as low noise amplifiers (LNA) and voltage controlled oscillators (VCO). The design of spiral inductors has a direct influence on the performance of these circuits. Recently proposed optimization methods for spiral inductors are usually based on circuit models, which are computationally efficient but inaccurate compared with full-wave electromagnetic (EM) simulations.</p> <p> For the first time, we develop an optimization technique for the design of spiral inductors and LC resonators exploiting both the computational efficiency of a (cheap) circuit model and the accuracy of a full-wave EM analysis, based on geometric programming (GP) and space mapping (SM). With the new technique, we can efficiently obtain EM-validated designs with considerable improvement over those obtained with traditional optimization methods.</p> / Thesis / Master of Applied Science (MASc)

Portable communication systems require, in part, high-efficiency radio frequency power amplifiers (RF PA) if battery lifetime is to be conserved. Conventional amplifier classifications and definitions are presented in a unified and concise format. The Bipolar Junction Transistor (BJT) and Metal-Semiconductor Field Effect Transistor (MESFET) are evaluated as active devices in high-efficiency RF PA designs. Two amplifier classes (class CE and class F) meet the system requirements of an 850 MHz operating frequency, a power output of 3 W, a battery supply voltage of 9 Vdc, and a sinusoidal-type signal to be amplified. Both classes are evaluated through recent research literature and simulated using the PSpice® computer simulation program. Class CE and class F are found to provide efficiencies exceeding 80 percent under the given system constraints.</p. / Master of Science