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Behavioural Modeling and Linearization of RF Power Amplifier using Artificial Neural NetworksMkadem, Farouk January 2010 (has links)
Power Amplifiers (PAs) are the key building blocks of the emerging wireless radios systems. They dominate the power consumption and sources of distortion, especially when driven with modulated signals. Several approaches have been devised to characterize the nonlinearity of a PA. Among these approaches, dynamic amplitude (AM/AM) and phase (AM/PM) distortion characteristics are widely used to characterize the PA nonlinearity and its effects on the output signal in power, frequency or time domains, when driven with realistic modulated signals. The inherent nonlinear behaviour of PAs generally yield output signals with an unacceptable quality, an undesirable level of out-of-band emission, high Error Vector Magnitudes (EVMs) and low Adjacent Channel Power Ratios (ACPRs), which usually fail to meet the established performance standards.
Traditionally, PAs are forced to operate deeply in their back-off region, far from their power capacity, in order to pass the mandatory spectrum mask (ACPR requirement) and to achieve acceptable EVM. Despite its simplicity, this solution is increasingly discarded, as it leads to cost and power inefficient radios. Alternatively, several linearization techniques, such as feedback, feed-forward and predistortion, have been devised to tackle PA nonlinearity and, consequently, improve the achievable the linearity versus power efficiency trade-off.
Among these linearization techniques, the Digital Pre-Distortion (DPD) technique consists of incorporating an extra nonlinear function before the PA, in order to preprocess the input signal to the PA, so that the overall cascaded systems behave linearly. The overall linearity of the cascaded system (DPD plus PA) relies primarily on the ability of the DPD function to produce nonlinearities that are equal in magnitude and out-of-phase to those generated by the PA. Hence, a good understanding and accurate modeling of PA distortions is a crucial step in the construction of an adequate DPD function.
This thesis explores DPD through techniques based on Artificial Neural Networks (ANNs). The choice of ANN as a modeling tool was motivated by its proven strength in modeling dynamic nonlinear systems. This thesis starts by providing a summary of the PA nonlinearity problem background, as well as an overview of the most well-known linearization techniques, with a special focus on DPD techniques. The thesis then discusses ANN structures and the learning parameters. Finally, a novel Two Hidden Layers ANN (2HLANN) model is suggested to predict the dynamic nonlinear behaviour of wideband PAs. An extensive validation of the 2HLANN model demonstrates its excellent modeling accuracy and linearization capability.
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60 Watts Broadband Push Pull RF Power Amplifier Using LTCC TechnologyJundi, Ayman 23 September 2013 (has links)
The continuous increase in wireless usage forces an immense pressure on wireless communication in terms of increased demand and spectrum scarcity. Service providers for communication services had no choice but to allocate new parts of the spectrum and present new communication standards that are more spectrally efficient. Communication is not only limited to mobile phones but recently attention has been given to intelligent transportation systems (ITS) where cars will be given a significant place in the communication network. Vehicular Ad-Hoc Network (VANET) is already assigned a slice of the spectrum at 5.9GHz using the IEEE802.11p standard also known as Dedicated Short-Range Communication (DSRC); however, this assignment will have limited range and functionality at first, and users are expected to depend on existing wireless mobile channels for some services such as video streaming and car entertainment. Therefore, it is essential to integrate existing wireless mobile communication standards into the skeleton of ITS at launch and most probably permanently.
An investigation was carried out regarding the existing communication standards including wireless local area networks (WLAN) and it was found that frequency bands from 400MHz up to 6GHz are being used in various regions around the world. It is also noted that current state of the art transceivers are composed of several transmitter front-ends targeting certain bands and standards. However, the more standards to be supported the more components to be added and the higher the cost not to mention the limited space in mobile devices. Multimode Multiband (MMMB) transmitters are therefore proposed as a potential solution to the existing redundancy in the number of front-end paths in modern transmitters. Broadband amplifiers are an essential part of any MMMB transmitter and they are also among the most challenging especially for high power requirements. This work explains why single ended topologies with efficiencies higher than 50% have a fundamental bandwidth limit such that the highest frequency of operation must be lower than twice the lowest frequency of operation. Hence, Push-Pull amplifier topology is being proposed as it was found that it has inherent broadband capabilities exceeding those of other topologies with comparable efficiency. The major advantage of Push-Pull power amplifiers is its capability of isolating the even harmonics present in the even mode operation of a Push-Pull amplifier from the less critical odd mode harmonics and the fundamental frequency. This separation between even and odd signals comes from the inclusion of a Balun at the output of push-pull amplifiers. Such separation makes it possible to operate amplifiers beyond the existing limit of single ended power amplifiers. To prove the concept, several Baluns were designed and tested and a comparison was made between different topologies in terms of balance, bandwidth and odd and even mode performances; moreover, to illustrate the concept a Push-Pull power amplifier design was implemented using the multilayer Low Temperature Co-fired Ceramics (LTCC) technology with a bandwidth ratio of more than 100%.
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RF power amplifiers and MEMS varactorsMahdavi, Sareh. January 2007 (has links)
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.
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Computer-aided design of RF MOSFET power amplifiers.Hoile, Gary Alec. January 1992 (has links)
The process of designing high power RF amplifiers has in the past relied heavily on
measurements, in conjunction with simple linear theory. With the advent of the
harmonic balance method and increasingly faster computers, CAD techniques can be
of great value in designing these nonlinear circuits.
Relatively little work has been done in modelling RF power MOSFETs. The methods
described in numerous papers for the nonlinear modelling of microwave GaAsFETs
cannot be applied easily to these high power devices. This thesis describes a
modelling procedure applicable to RF MOSFETs rated at over 100 W. This is
achieved by the use of cold S parameters and pulsed drain current measurements
taken at controlled temperatures. A method of determining the required device
thermal impedance is given.
A complete nonlinear equivalent circuit model is extracted for an MRF136
MOSFET, a 28 V, 15 W device. This includes two nonlinear capacitors. An
equation is developed to describe accurately the drain current as a function of the
internal gate and drain voltages. The model parameters are found by computer
optimisation with measured data. Techniques for modelling the passive components
in RF power amplifiers are given. These include resistors, inductors, capacitors, and
ferrite transformers. Although linear ferrite transformer models are used, nonlinear
forms are also investigated.
The accuracy of the MOSFET model is verified by comparison to large signal
measurements in a 50 0 system. A complete power amplifier using the MRF136,
operating from 118 MHz to 175 MHz is built and analysed. The accuracy of
predictions is generally within 10 % for output power and DC supply current, and
around 30 % for input impedance. An amplifier is designed using the CAD package,
and then built, requiring only a small final adjustment of the input matching circuit.
The computer based methods described lead quickly to a near-optimal design and
reduce the need for extensive high power measurements. The use of nonlinear
analysis programs is thus established as a valuable design tool for engineers working
with RF power amplifiers. / Thesis (Ph.D.)-University of Natal, Durban, 1992.
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Large signal electro-thermal LDMOSFET modeling and the thermal memory effects in RF power amplifiersDai, Wenhua, January 2004 (has links)
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).
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A base control Doherty power amplifier design for improved efficiency in GSM handsets /Ferwalt, Darren W. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2004. / Printout. Includes bibliographical references (leaves 73-75). Also available on the World Wide Web.
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Adaptive digital polynomial predistortion linearisation for RF power amplifiers : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Engineering in Electrical and Computer Engineering at the University of Canterbury, Christchurch, New Zealand /Giesbers, D. M. January 1900 (has links)
Thesis (M.E.)--University of Canterbury, 2008. / Typescript (photocopy). "August 2008." Includes bibliographical references (p. [123]-126). Also available via the World Wide Web.
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Broadband CMOS power amplifier for IEEE 802.11 a/b/g wireless LAN transmittersChiu, Chin-Yung. January 2005 (has links)
Thesis (Ph. D.)--Ohio State University, 2005. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2008 Dec 1
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A phase-time modulation scheme for peak-to-average power mitigation in multi-carrier wireless transmission : a thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering (Electrical and Electronic Engineering), University of Canterbury, Christchurch, New Zealand /Spalding, David I. January 1900 (has links)
Thesis (M.E.)--University of Canterbury, 2006. / Typescript (photocopy). "31 May 2006." Includes bibliographical references (p. R1-R5). Also available via the World Wide Web.
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Evaluation of Doherty Amplifier ImplementationsJansen, Roelof 03 1900 (has links)
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.
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