6 research outputs found
Continuous Mode High Efficiency Power Amplifier Design for X Band
This thesis is focused on the investigation and implementation of novel techniques for the
design of X band (8 - 12GHz) power amplifiers.
One of the main topics is the expansion and novel implementation of continuous mode
theory, with the intention of improving the bandwidth and efficiency of X band power
amplifiers. This work builds upon the Class B/J continuous mode theory to incorporate
cases where <[ZF0] 6= RL, not described by the original Class B/J theory, with a tool
called the “clipping contour”.
The clipping contour tool shows a graphical representation on the Smith chart of
the boundary between impedances generating a voltage waveform which will modulate
or “clip” the current waveform, and a voltage waveform which will leave the current
waveform unaltered. This non-clipping space is shown, with measured load pull and
amplifier data, to represent the maximum efficiency case for a given ZF0, thus the clipping
contour tool thus gives designers the ability to predict the areas of highest efficiency and
power given any ZF0, without the need to use costly, time consuming multi harmonic load
pull techniques.
Push pull amplifiers using quarter wave coupled line baluns are proposed as an ideal
matching topology to exploit this new tool. Various balun topologies are studied using
a novel extended transmission line model. This model is shown to predict accurately
and explain the “trace separation” effect seen in planar baluns and not their 3D coaxial
cable equivalents. It also forms the basis of analysis which results in a powerful new
equation capable of guaranteeing the elimination of trace separation completely, without
compromising performance. This equation is used to design an optimal balun which
possesses the largest fractional bandwidth (130%) of any balun ever published on single
layer thin film Alumina, whilst simultaneously eliminating trace separation.
The optimised Alumina baluns are used to construct push pull output demonstrator
circuits which show efficiencies of 40% over greater than an octave bandwidth, a significant
advancement of any other comparable published work. These techniques demonstrate the
potential to exceed double octave bandwidths with efficiencies greater than 40% once
optimised. Initial investigations on MMIC and 2.5D processes show the potential to
replicate the Alumina performance over octave and decade bandwidths respectively
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Design and Linearization of Energy Efficiency Power Amplifier in Nonlinear OFDM Transmitter for LTE-5G Applications. Simulation and measurements of energy efficiency power amplifier in the presence of nonlinear OFDM transmitter system and digital predistortion based on Hammerstein-Wiener method
This research work has made an effort to understand a novel line of radio frequency
power amplifiers (RFPAs) that address initiatives for efficiency enhancement and
linearity compensation to harmonize the fifth generation (5G) campaign. The objective
is to enhance the performance of an orthogonal frequency division multiplexing-long
term evolution (OFDM-LTE) transmitter by reducing the nonlinear distortion of the
RFPA.
The first part of this work explores the design and implementation of 15.5 W class AB
RF power amplifier, adopting a balanced technique to stimulate efficiency enhancement
and redeeming exhibition of excessive power in the transmitter. Consequently, this work
goes beyond improving efficiency over a linear RF power amplifier design; in which a
comprehensive investigation on the fundamental and harmonic components of class F
RF power amplifier using a load-pull approach to realise an optimum load impedance
and the matching network is presented. The frequency bandwidth for both amplifiers was
allocated to operate in the 2.620-2.690 GHz of mobile LTE applications.
The second part explores the development of the behavioural model for the class AB
power amplifier. A particular novel, Hammerstein-Wiener based model is proposed to
describe the dynamic nonlinear behaviour of the power amplifier. The RF power amplifier
nonlinear distortion is approximated using a new linear parameter approximation
approach. The first and second-order Hammerstein-Wiener using the Normalised Least
Mean Square Error (NLMSE) algorithm is used with the aim of easing the complexity of
filtering process during linear memory cancellation. Moreover, an enhanced adaptive
Wiener model is proposed to explore the nonlinear memory effect in the system. The
proposed approach is able to balance between convergence speed and high-level
accuracy when compared with behavioural modelling algorithms that are more complex
in computation.
Finally, the adaptive predistorter technique is implemented and verified in the OFDM
transceiver test-bed. The results were compared against the computed one from
MATLAB simulation for OFDM and 5G modulation transmitters. The results have
confirmed the reliability of the model and the effectiveness of the proposed predistorter.FundacĂŁo para a CiĂŞncia e a Tecnologia, Portugal, under
European Union’s Horizon 2020 research and innovation programme ... grant agreement H2020-MSCA-ITN- 2016 SECRET-722424
I also acknowledge the role of the National Space Research and Development Agency (NASRDA)
Sokoto State Government
Petroleum Technology Trust Fund (PTDF
Wide Bandgap Based Devices
Emerging wide bandgap (WBG) semiconductors hold the potential to advance the global industry in the same way that, more than 50 years ago, the invention of the silicon (Si) chip enabled the modern computer era. SiC- and GaN-based devices are starting to become more commercially available. Smaller, faster, and more efficient than their counterpart Si-based components, these WBG devices also offer greater expected reliability in tougher operating conditions. Furthermore, in this frame, a new class of microelectronic-grade semiconducting materials that have an even larger bandgap than the previously established wide bandgap semiconductors, such as GaN and SiC, have been created, and are thus referred to as “ultra-wide bandgap” materials. These materials, which include AlGaN, AlN, diamond, Ga2O3, and BN, offer theoretically superior properties, including a higher critical breakdown field, higher temperature operation, and potentially higher radiation tolerance. These attributes, in turn, make it possible to use revolutionary new devices for extreme environments, such as high-efficiency power transistors, because of the improved Baliga figure of merit, ultra-high voltage pulsed power switches, high-efficiency UV-LEDs, and electronics. This Special Issue aims to collect high quality research papers, short communications, and review articles that focus on wide bandgap device design, fabrication, and advanced characterization. The Special Issue will also publish selected papers from the 43rd Workshop on Compound Semiconductor Devices and Integrated Circuits, held in France (WOCSDICE 2019), which brings together scientists and engineers working in the area of III–V, and other compound semiconductor devices and integrated circuits
DESIGN TECHNIQUES FOR HIGH-EFFICIENCY MICROWAVE POWER AMPLIFIERS
The increasingly diffusion of wireless devices during the last years has established a sort of
“second youth” of analog electronics related to telecommunication systems. Nowadays, in fact,
electronic equipments for wireless communication are exploited not only for niche sectors as
strategic applications (e.g., military, satellite and so on): as a matter of fact, a large number of
commercial devices exploit wireless transmitting systems operating at RF and microwave
frequencies.
As a consequence, increasing interest has been focused by academic and industrial communities
on RF and microwave circuits and in particular on power amplifiers, that represent the core of a
wireless transmitting system. In this context, more and more challenging performance are
demanded to such a kind of circuit, especially in terms of output power, bandwidth and efficiency.
The present thesis work has been focused on RF and microwave power amplifier design that, as
said before, represents one of most actual and attractive research theme. Several aspects of such
topic have been covered, from the analysis of different design techniques available in literature to
the development of an innovative design approach, providing many experimental results related to
realized power amplifiers. Particular emphasis has been given to high-efficiency power amplifier
classes of operation, that represent an hot issue in a world more and more devoted to the energy
conservation. Moreover, electron device degradation phenomena were investigated, that although
not directly accounted for, represent a key issue in microwave power amplifier design.
In particular, the first chapter of this thesis provides an overview of commonly adopted design
methodologies for microwave power amplifier, analyzing the advantages and the critical aspects of
such approaches. Moreover, nonlinear device modeling issues oriented to microwave power
amplifier design have been dealt with.
In the second chapter, an innovative design technique is presented. It is based on experimental
electron device nonlinear characterization, carried out by means of a low-frequency large signal
measurement setup, in conjunction with the modeling of high-frequency nonlinear dynamic
phenomena. Several design examples have been carried out by exploiting the proposed approach
that confirm the effectiveness of the design technique.
In the third chapter, the proposed design methodology has been applied to high-efficiency power
amplifier classes of operations, that need to control the device terminations not only at the
fundamental frequency, but also at harmonics. Two high-efficiency power amplifiers have been realized by adopting such a technique, demonstrating performance in terms of output power and
efficiency comparable with the state of the art.
Finally, in chapter four an important power amplifier design aspect has been dealt with, related
to degradation and performance limitation of microwave electron devices. Several experimental
results have been carried out by exploiting a new measurement setup, oriented to the
characterization of degradation phenomena of microwave electron devices