Tesi: "Power amplifiers"

1

Shao, Jin. "Advanced Power Amplifiers Design for Modern Wireless Communication". Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc804973/.

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Modern wireless communication systems use spectrally efficient modulation schemes to reach high data rate transmission. These schemes are generally involved with signals with high peak-to-average power ratio (PAPR). Moreover, the development of next generation wireless communication systems requires the power amplifiers to operate over a wide frequency band or multiple frequency bands to support different applications. These wide-band and multi-band solutions will lead to reductions in both the size and cost of the whole system. This dissertation presents several advanced power amplifier solutions to provide wide-band and multi-band operations with efficiency improvement at power back-offs.

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2

Lee, Ockgoo. "High efficiency switching CMOS power amplifiers for wireless communications". Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/37145.

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High-efficiency performance is one of the most important requirements of power amplifiers (PAs) for wireless applications. However, the design of highly efficient CMOS PAs for watt-level applications is a challenging task. This dissertation focuses on the development of the design method for highly efficient CMOS PAs to overcome the fundamental difficulties presented by CMOS technology. In this dissertation, the design method and analysis for a high-power and highefficiency class-E CMOS PA with a fully integrated transformer have been presented. This work is the first effort to set up a comprehensive design methodology for a fully integrated class-E CMOS PA including effects of an integrated transformer, which is very crucial for watt-level power applications. In addition, to improve efficiency of cascode class-E CMOS PAs, a charging acceleration technique is developed. The method accelerates a charging speed to turn off the common-gate device in the off-state, thus reducing the power loss. To demonstrate the proposed cascode class-E PA, a prototype CMOS PA was implemented in a 0.18-μm CMOS process. Measurements show an improvement of approximately 6% in the power added efficiency. The proposed cascode class-E PA structure is suitable for the design of high-efficiency class-E PAs while it reduces the voltage stress across the device.

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3

Hur, Joonhoi. "A highly linear and efficient out-phasing transmitter for multi-band, multi-mode applications". Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42823.

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There have been many efforts to improve efficiency of transmitter while meeting stringent linearity requirement of modern communication system. Among the technology to enhance efficiency of linear transmitter, the out-phasing technologies, also called the linear amplification with nonlinear components (LINC), is considered as a promising technology. LINC has been studied long times, since it provides excellent linearity with high efficiency by allowing adopt high efficient switch-mode power amplifiers. However, The LINC transmitter has some technical challenges: linearity degradation due to amplitude and phase mismatches, efficiency degradation due to poor combining efficiency, and narrow frequency bandwidth due to output matching network of switching power amplifier. In this thesis, some state-of-the-art techniques for solving the problems of LINC transmitters are presented. An unbalanced phase calibration technique compensates amplitude/phase mismatches between two parallel paths in the LINC system, and multi-level LINC (MLINC) and an uneven multi-level LINC (UMLINC) structure improve the overall power efficiency. And the reconfigurable Class-D switching PA enables multi-band operation with high efficiency and good linearity. With these techniques, the new multi-band out-phasing transmitter improves the efficiency without sacrificing the linearity performance.

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4

Bell, Patrick J. "MEMS-reconfigurable microwave power amplifiers". Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3219036.

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5

Mutha, Shashank. "Adaptive Linearization of Power Amplifiers". The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1244049195.

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6

Al, Tanany Ahmed. "A Study of Switched Mode Power Amplifiers using LDMOS". Thesis, University of Gävle, Department of Technology and Built Environment, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-701.

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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.

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7

Yousefzadeh, Vahid. "Digitally controlled power converters for RF power amplifiers". Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3219220.

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8

Gray, Blake Raymond. "Design of RF and microwave parametric amplifiers and power upconverters". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43613.

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The objective of this research is to develop, characterize, and demonstrate novel parametric architectures capable of wideband operation while maintaining high gain and stability. To begin the study, phase-incoherent upconverting parametric amplifiers will be explored by first developing a set of analytical models describing their achievable gain and efficiency. These models will provide a set of design tools to optimize and evaluate prototype circuit boards. The prototype boards will then be used to demonstrate their achievable gain, bandwidth, efficiency, and stability. Further investigation of the analytical models and data collected from the prototype boards will conclude bandwidth and gain limitations and end the investigation into phase-incoherent upconverting parametric amplifiers in lieu of negative-resistance parametric amplifiers. Traditionally, there were two versions of negative-resistance parametric amplifiers available: degenerate and non-degenerate. Both modes of operation are considered single-frequency amplifiers because both the input and output frequencies occur at the source frequency. Degenerate parametric amplifiers offer more power gain than their non-degenerate counterpart and do not require additional circuitry for idler currents. As a result, a phase-coherent degenerate parametric amplifier printed circuit board prototype will be built to investigate achievable gain, bandwidth, and stability. Analytical models will be developed to describe the gain and efficiency of phase-coherent degenerate parametric amplifiers. The presence of a negative resistance suggests the possibility of instability under certain operating conditions, therefore, an in-depth stability study of phase-coherent degenerate parametric amplifiers will be performed. The observation of upconversion gain in phase-coherent degenerate parametric amplifiers will spark investigation into a previously unknown parametric architecture: phase-coherent upconverting parametric amplifiers. Using the phase-coherent degenerate parametric amplifier prototype board, stable phase-coherent upconversion with gain will be demonstrated from the source input frequency to its third harmonic. An analytical model describing the large-signal transducer gain of phase-coherent upconverting parametric amplifiers from the first to the third harmonic of the source input will be derived and validated using the prototype board and simulations.

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9

Lehtisalo, V. (Ville). "Average power tracking optimization system for LTE power amplifiers". Master's thesis, University of Oulu, 2014. http://jultika.oulu.fi/Record/nbnfioulu-201409171871.

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Abstract. This thesis introduces the design and implementation of an optimization system for average power tracking, used in the RF power amplifier of LTE mobile device. Average power tracking adjusts the supplied voltage of the power amplifier according to output power level so that the linearity of the power amplifier is maintained while the efficiency is improved. The optimization system is implemented with computer controlled measurement equipment setup. The setup consists of an RF signal generator, a power meter and a spectrum analyzer. Performance measurements are performed to the device under test with different bias voltages of the PA and various output power levels, separately for two different power modes of the power amplifier. The performance measurements focus on the ratio of transmission channel power and adjacent channel power. Total efficiency and gain of the device and the current consumption of the power amplifier were also measured. Based on the measurement results, the most suitable voltage for the power amplifier can be selected for each power level with a voltage table optimizing algorithm. The algorithm compares the measured adjacent channel leakage ratio to a predetermined target value and selects the lowest linearity requirements fulfilling a voltage value for the power amplifier. The effects of output power and supplied voltage on the linearity, gain and efficiency of the device are observed. The results show that the performance of the device under test is greatly dependent on the bias voltage of the power amplifier. In addition, the effect of ambient temperature and different frequency channels on the linearity and gain are observed. The measurements show that the temperature affects marginally the gain whereas linearity is more dependent on the used frequency channel. Finally the suitability of the optimized bias voltage table is verified by using it to adjust the power amplifier of a separate test board. The linearity of the product is verified by measuring the adjacent channel leakage ratio and comparing it to official requirements. The voltage table generated with the optimizing algorithm based on the results obtained with the measurement setup is well suited for improving the power amplifier efficiency with average power tracking. It is a fast method to obtain a wide range of measurement results of the performance of a power amplifier with various output power levels and bias voltages.Keskimääräisen tehonseurannan optimointisysteemi LTE-tehovahvistimille. Tiivistelmä. Tässä diplomityössä esitellään LTE-tiedonsiirtotekniikkaa tukevassa matkapuhelimessa käytettävän RF-tehovahvistimen keskimääräisen tehonseurannan optimointisysteemin suunnittelu ja toteutus. Keskimääräinen tehonseuranta säätää tehovahvistimen käyttöjännitettä lähtötehon perusteella niin, että tehovahvistimen lineaarisuus säilytetään ja hyötysuhde paranee. Optimointisysteemi toteutettiin tietokone-ohjatulla mittalaitekokoonpanolla sekä tulostenkäsittelyalgoritmilla. Mittalaitekokoonpano koostuu RF-signaaligeneraattorista, tehomittarista ja spektrianalysaattorista. Testilaitteelle suoritetaan suorituskykymittauksia eri tehovahvistimen jännitearvoilla ja usealla lähtötehotasolla, erikseen kahdelle eri vahvistimen tehotilalle. Suorituskykymittaukset keskittyvät lähetyskanavan sekä viereisen kanavan tehon suhteen mittaukseen. Myös hyötysuhde, kokonaisvahvistus sekä testilaitteen tehovahvistimen virrankulutus mitataan suorituskykymittausten yhteydessä. Mittaustulosten perusteella jännitetaulukon optimointialgoritmilla saadaan valittua sopivin tehovahvistimelle syötettävä jännite kullekin lähtötehotasolle. Algoritmi vertaa viereisen kanavan vuototehon suuruutta asetettuun tavoitearvoon ja valitsee tehovahvistimelle matalimman lineaarisuusvaatimukset täyttävän jännitteen. Havaintoja tehdään testilaitteen tehovahvistimen lineaarisuuden, vahvistuskertoimen ja hyötysuhteen riippuvuudesta lähtötehoon sekä käyttöjännitteeseen. Tuloksista nähdään syötettävän jännitteen vaikuttavan voimakkaasti testilaitteen suorituskykyyn. Myös ympäröivän lämpötilan sekä taajuuskanavan vaikutusta tehovahvistimen lineaarisuuteen ja vahvistuskertoimeen tutkitaan. Mittaukset osoittavat lämpötilan vaikuttavan tehovahvistimen vahvistuskertoimeen marginaalisesti. Sen sijaan lineaarisuuteen vaikuttaa enemmän käytettävä taajuuskanava. Lopuksi optimoidun jännitetaulukon soveltuvuus varmistetaan käyttämällä sitä erillisellä testilevyllä tehovahvistimen jännitteen säätämiseen. Varmistusmittauksissa lineaarisuus testataan mittaamalla viereisen kanavan vuototehon suuruus ja vertaamalla sitä asetettuihin virallisiin vaatimuksiin. Mittalaitekokoonpanolla saatujen mittaustulosten sekä optimointialgoritmin perusteella luotu jännitetaulukko soveltuu hyvin tehovahvistimen hyötysuhteen parantamiseen keskimääräisen tehonseurannan avulla. Se on nopea tapa saada mittaustuloksia tehovahvistimen suorituskyvystä laajalta lähtötehoalueelta eri jännitearvoilla.

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10

Al-Tahir, Hibah. "Multidimensional Measurements : on RF Power Amplifiers". Thesis, University of Gävle, Department of Technology and Built Environment, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-729.

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Abstract

In this thesis, a measurement system was set to perform comprehensive measurements on RF power amplifiers. Data obtained from the measurements is then processed mathematically to obtain three dimensional graphs of the basic parameters affected or generated by nonlinearities of the amplifier i.e. gain, efficiency and distortion. Using a class AB amplifier as the DUT, two sets of signals – both swept in power level and frequency - were generated to validate the method, a two-tone signal and a WCDMA signal. The three dimensional plot gives a thorough representation of the behavior of the amplifier in any arbitrary range of spectrum and input level. Sweet spots are consequently easy to detect and analyze. The measurement setup can also yield other three dimensional plots of variations of gain, efficiency or distortion versus frequencies and input levels. Moreover, the measurement tool can be used to plot traditional two dimensional plots such as, input versus gain, frequency versus efficiency etc, making the setup a practical tool for RF amplifiers designers.

The test signals were generated by computer then sent to a vector signal generator that generates the actual signals fed to the amplifier. The output of the amplifier is fed to a vector signal analyzer then collected by computer to be handled. MATLAB® was used throughout the entire process.

The distortion considered in the case of the two-tone signals is the third order intermodulation distortion (IM3) whereas Adjacent Channel Power Ratio (ACPR) was considered in the case of WCDMA.

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11

Condo, Neira Edith Graciela. "Multidimensional Measurements on RF Power Amplifiers". Thesis, University of Gävle, Department of Technology and Built Environment, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-804.

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Measurements are important to specify and verify properties for components, modules and systems. The specifications for a certain figure of merit are usually given in a numerical value or a two dimensional plot. However, there are some devices, like power amplifiers with certain figure of merits that depends on two or more working conditions, requiring a three dimensional plot.

This thesis presents a measurement method including graphical user interface of three parameters gain, efficiency and distortion when two-tone or WCDMA signals are used as an input to the PA.

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12

McRory, John Godfrey. "Stacked GaAs FET RF power amplifiers". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0002/NQ31049.pdf.

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13

Mahdavi, Sareh. "RF power amplifiers and MEMS varactors". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112576.

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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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14

Zewani, Mohammed. "Low distortion wideband microwave power amplifiers". Thesis, University of Leeds, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440631.

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15

Phạm, Anh D. 1974. "Biasing techniques for linear power amplifiers". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87274.

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16

Phạm, Anh D. 1974. "Outphase power amplifiers in OFDM systems". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/35285.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2006.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (leaves 93-95).
A trade-off between linearity and efficiency exists in conventional power amplifiers. The outphase amplifying concept overcomes this trade-off by enabling the use of high efficiency, non-linear power amplifiers for linear amplification. An amplitude modulated signal is first decomposed into two constant amplitude, phase modulated signals that can be amplified using two high efficiency switching power amplifiers. The two outputs are then recombined to restore the original amplitude modulated signal. In this manner, an outphase power amplifier can simultaneously achieve high efficiency and good linearity. This thesis investigates the capability of the outphase amplifying technique in modern wireless communication. First, a digital amplitude-to-phase conversion scheme is proposed to facilitate the outphase decomposition. By taking advantage of the available computational power in current digital technology, the amplitude-to-phase conversion can be implemented with both accuracy and efficiency in the digital domain. A proof-of-concept outphase power amplifier is fabricated using the IBM 7WL SiGe BiCMOS process technology.
(cont.) The test chip includes two class-E power amplifiers and the first 5.8GHz fully integrated Wilkinson power combiner. The low-loss integrated combiner allows efficient outphase recombining while providing the necessary input isolation for a robust outphase power amplifier. The outphase power amplifier achieves an efficiency of 47% at the maximum output power of 18.5 dBm. For an input Orthogonal Frequency Division Multiplexing (OFDM) signal of 32 sub-channels of 64-QAM, the adjacent channel power leakage ratio (ACPR) is better than 32dBc. The outphase power amplifier's error vector magnitude (EVM) is better than -25dB for up to 20dB of output dynamic range.102 Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.
by Anh D. Pham.
Ph.D.

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17

Smith, Robert Martin. "Broadband microwave push-pull power amplifiers". Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/58895/.

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The research work presented in this thesis aims to achieve high-power, high-efficiency amplification across substantial bandwidths at microwave frequencies. The push-pull topology was identified as a promising possible solution which had previously not been considered for this application. The key component in the push-pull power amplifier is the balun, which converts between balanced and unbalanced signal environments. The novel use of ferrite materials allowed the half-wavelength resonance of a coaxial-cable transmission line balun to be suppressed, greatly extending its bandwidth. This was done by utilising the resistive properties of the ferrite material at frequencies greater than 1 GHz, at which these materials are not usually studied. The multi-decade performance of the transmission line baluns opened up the possibil- ity of realising push-pull power amplifiers across similar bandwidths. The measurement of these baluns revealed that they present a resistive impedance to the odd-harmonic frequencies, and an open circuit to the even-harmonic frequencies. This is a significant departure from the conventional view of the push-pull mode, and led to the modes of operation inside a microwave push-pull power amplifier being reconsidered. Factorised waveform expressions were used to describe the new modes of operation, and these were verified through load-pull simulations and measurements. The wave- forms were found to resemble the inverted modes of operation, with similar desirable characteristics such as high efficiency and an increase in output power compared to Class A. The viability of the push-pull amplifier topology was demonstrated through two pro- totype amplifiers, which achieved high output power levels and efficiencies over multi- octave bandwidths. Measurement systems for characterising and analysing these amplifiers were developed, which should lead to improved understanding and better performance in future.

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18

Tomé, Pedro Mirassol. "Analog neural predistortion of power amplifiers". Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17166.

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Mestrado em Engenharia Electrónica e Telecomunicações
As especificações das redes de telecomunicações de quinta geração ultrapassam largamente as capacidades das técnicas mais modernas de linearização de amplificadores de potência como a pré-distorção digital. Por esta razão, esta tese propõe um método de linearização alternativo: um prédistorçor analógico, à banda base, constituído por uma rede neuronal artificial. A rede foi treinada usando três métodos distintos: avaliação de política através de TD(λ), otimização por estratégias de evolução como CMA-ES, e um algoritmo original de aproximações sucessivas. Apesar do TD(λ) não ter produzido resultados de simulação satisfatórios, os resultados dos outros dois métodos foram excelentes: um NMSE entre as funções de transferência pretendida e efetiva do amplificador pré-distorcido até -70 dB, e uma redução total das componentes de distorção do espetro de frequência de um sinal GSM de teste. Apesar das estratégias de evolução terem alcançado este nível de linearização após cerca de 4 horas de execução contínua, o algoritmo original consegue fazê-lo numa questão de segundos. Desta forma, esta tese abre caminho para que se cumpram as exigências das redes de nova geração.
Fifth-generation telecommunications networks are expected to have technical requirements which far outpace the capabilities of modern power amplifier (PA) linearization techniques such as digital predistortion. For this reason, this thesis proposes an alternative linearization method: a base band analog predistorter consisting of an artificial neural network. The network was trained through three very distinct methods: policy evaluation using TD(λ), optimization using evolution strategies such as CMA-ES, and an original algorithm of successive approximations. While TD(λ) proved to be unsuccessful, the other two methods produced excellent simulation results: an NMSE between the target and the predistorted PA transfer functions up to -70 dB, and the complete elimination of distortion components in the frequency spectrum of a GSM test signal. While the evolution strategies achieved this level of linearization after about 4 hours of continuous work, the original algorithm consistently does so in a matter of seconds. In effect, this thesis outlines a way towards the meeting of the specifications of next-generation networks.

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Wang, Chengzhou. "CMOS power amplifiers for wireless communications /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2003. http://wwwlib.umi.com/cr/ucsd/fullcit?p3112826.

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20

An, Kyu Hwan. "CMOS RF power amplifiers for mobile wireless communications". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31717.

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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Laskar, Joy; Committee Member: Cressler, John; Committee Member: Kohl, Paul; Committee Member: Kornegay, Kevin; Committee Member: Tentzeris, Emmanouil. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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21

Kim, Hyun-Woong. "CMOS RF transmitter front-end module for high-power mobile applications". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/47592.

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With the explosive growth of the wireless market, the demand for low-cost and highly-integrated radio frequency (RF) transceiver has been increased. Keeping up with this trend, complimentary metal-oxide-semiconductor (CMOS) has been spotlighted by virtue of its superior characteristics. However, there are challenges in achieving this goal, especially designing the transmitter portion. The objective of this research is to demonstrate the feasibility of fully integrated CMOS transmitter module which includes power amplifier (PA) and transmit/receive (T/R) switch by compensating for the intrinsic drawbacks of CMOS technology. As an effort to overcome the challenges, the high-power handling T/R switches are introduced as the first part of this dissertation. The proposed differential switch topology and feed-forward capacitor helps reducing the voltage stress over the switch devices, enabling a linear power transmission. With the high-power T/R switches, a new transmitter front-end topology - differential PA and T/R switch topology with the multi-section PA output matching network - is also proposed. The multi-stage PA output matching network assists to relieve the voltage stress over the switch device even more, by providing a low switch operating impedance. By analyzing the power performance and efficiency of entire transmitter module, design methodology for the high-power handling and efficient transmitter module is established. Finally, the research in this dissertation provides low-cost, high-power handling, and efficient CMOS RF transmitter module for wireless applications.

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Connor, Mark Anthony. "Design of Power-Scalable Gallium Nitride Class E Power Amplifiers". University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1405437893.

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23

Fedorenko, Pavlo. "Phase distortion in envelope elimination and restoration radio frequency power amplifiers". Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/34822.

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The objective of this research is to analyze and improve linearity of envelope elimination and restoration (EER) radio frequency (RF) power amplifiers. Envelope elimination and restoration was compared to other efficiency enhancement techniques and determined to likely be the most suitable solution for implementation of multimode, multiband portable RF transmitters. Distortion, stemming from dynamic power-supply modulation of RF transistors in EER RF power amplifiers was identified as one of the key challenges to the development of commercially viable EER transmitters. This dissertation presents a study of phase distortion in RF power amplifiers (PAs) with emphasis on identification of the origins of phase distortion in EER RF power amplifiers. Circuit-level techniques for distortion mitigation are also presented. Memory effects in conventional power amplifiers are investigated through the accurate measurement and analysis of phase asymmetry of out-of-band distortion components. Novel physically-based power amplifier model is developed for attributing measured memory effects to their physical origin. The amount of linearity correction, obtained through pre-distortion for a particular RF power amplifier, is then correlated to the behavior of the memory effects in the corresponding PA. Heterojunction field-effect transistor and heterojunction bipolar transistor amplifiers are used for investigation of voltage-dependent phase distortion in handset EER RF PAs. The distortion is found to stem from vector addition of signals, generated in nonlinear circuit elements of the PA. Specifically, nonlinear base-collector capacitance and downconversion of distortion components from second harmonic frequency are found to be the dominant sources of phase distortion. Shorting of second harmonic is proposed as a way to reduce the distortion contribution of the downconverted signal. Phase distortion is reduced by 50%, however a slight degradation in the amplitude distortion is observed. Push-pull architecture is proposed for EER RF power amplifiers to cancel distortion components, generated in the nonlinear base-collector capacitance. Push-pull implementation enables a 67% reduction in phase distortion, accompanied by a 1-2 dB reduction in amplitude distortion in EER RF power amplifiers. This work, combined with other studies in the field, will help advance the development of multimode, multiband portable RF transmitters, based on the envelope elimination and restoration architecture.

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24

Lotter, Paul. "Development of feedforward RF power amplifier". Thesis, Cape Peninsula University of Technology, 2006. http://hdl.handle.net/20.500.11838/2206.

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Thesis (MTech(Electrical Engineering))--Cape Peninsula University of Technology, 2006.
Electronic communication systems have become an integral part of our everyday lives. RF (Radio Frequency) power amplifiers form part of the fundamental building blocks of an electronic communication system. RF power amplifiers can also be one of the major causes of distortion in an electronic communication system. This thesis describes the linearity requirement for a RF power amplifier that is used in a transmitter section of an electronic communication system. Furthermore, five different linearisation techniques are presented and their characteristics compared. Since a power amplifier employing the Feedforward linearisation technique was designed, built and tested, this thesis focuses on the Feedforward technique. The design methods for the various Feedforward components are presented. The measured parameters of the Feedforward linearised amplifier are compared with the measured parameters of a non-linearised amplifier.

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Raich, Raviv. "Nonlinear system identification and analysis with applications to power amplifier modeling and power amplifier predistortion". Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-04072004-130800/unrestricted/raich%5Fraviv%5F200405%5Fphd.pdf.

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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2004.
Xiaoming Huo, Committee Member ; J. Stevenson Kenney, Committee Member ; Douglas Williams, Committee Member ; Erik Verriest, Committee Member ; G. Tong Zhou, Committee Chair. Vita. Includes bibliographical references (leaves 170-179).

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26

Srirattana, Nuttapong. "High-Efficiency Linear RF Power Amplifiers Development". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6899.

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Next generation mobile communication systems require the use of linear RF power amplifier for higher data transmission rates. However, linear RF power amplifiers are inherently inefficient and usually require additional circuits or further system adjustments for better efficiency. This dissertation focuses on the development of new efficiency enhancement schemes for linear RF power amplifiers. The multistage Doherty amplifier technique is proposed to improve the performance of linear RF power amplifiers operated in a low power level. This technique advances the original Doherty amplifier scheme by improving the efficiency at much lower power level. The proposed technique is supported by a new approach in device periphery calculation to reduce AM/AM distortion and a further improvement of linearity by the bias adaptation concept. The device periphery adjustment technique for efficiency enhancement of power amplifier integrated circuits is also proposed in this work. The concept is clearly explained together with its implementation on CMOS and SiGe RF power amplifier designs. Furthermore, linearity improvement technique using the cancellation of nonlinear terms is proposed for the CMOS power amplifier in combination with the efficiency enhancement technique. In addition to the efficiency enhancement of power amplifiers, a scalable large-signal MOSFET model using the modified BSIM3v3 approach is proposed. A new scalable substrate network model is developed to enhance the accuracy of the BSIM3v3 model in RF and microwave applications. The proposed model simplifies the modeling of substrate coupling effects in MOS transistor and provides great accuracy in both small-signal and large-signal performances.

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27

Fritzin, Jonas. "CMOS RF Power Amplifiers for Wireless Communications". Doctoral thesis, Linköpings universitet, Elektroniska komponenter, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-71852.

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The wireless market has experienced a remarkable development and growth since the introduction of the first modern mobile phone systems, with a steady increase in the number of subscribers, new application areas, and higher data rates. As mobile phones and wireless connectivity have become consumer mass markets, the prime goal of the IC manufacturers is to provide low-cost solutions. The power amplifier (PA) is a key building block in all RF transmitters. To lower the costs and allow full integration of a complete radio System-on-Chip (SoC), it is desirable to integrate the entire transceiver and the PA in a single CMOS chip. While digital circuits benefit from the technology scaling, it is becoming harder to meet the stringent requirements on linearity, output power, bandwidth, and efficiency at lower supply voltages in traditional PA architectures. This has recently triggered extensive studies to investigate the impact of different efficiency enhancement and linearization techniques, like polar modulation and outphasing, in nanometer CMOS technologies. This thesis addresses the potential of integrating linear and power-efficient PAs in nanometer CMOS technologies at GHz frequencies. In total eight amplifiers have been designed - two linear Class-A PAs, two switched Class-E PAs, and four Class-D PAs linearized in outphasing configurations. Based on the outphasing PAs, amplifier models and predistorters have been developed and evaluated for uplink (terminal) and downlink (base station) signals. The two linear Class-A PAs with LC-based and transformer-based input and interstage matching networks were designed in a 65nm CMOS technology for 2.4GHz 802.11n WLAN. For a 72.2Mbit/s 64-QAM 802.11n OFDM signal with PAPR of 9.1dB, both PAs fulfilled the toughest EVM requirement in the standard at average output power levels of +9.4dBm and +11.6dBm, respectively. The two PAs were among the first PAs implemented in a 65nm CMOS technology. The two Class-E PAs, intended for DECT and Bluetooth, were designed in 130nm CMOS and operated at low ‘digital’ supply voltages. The PAs delivered +26.4 and +22.7dBm at 1.5V and 1.0V supply voltages with PAE of 30% and 36%, respectively. The Bluetooth PA was based on thin oxide devices and the performance degradation over time for a high level of oxide stress was evaluated. The four Class-D outphasing PAs were designed in 65nm, 90nm, and 130nm CMOS technologies. The first outphasing design was based on a Class-D stage utilizing a cascode configuration, driven by an AC-coupled low-voltage driver, to allow a 5.5V supply voltage in a 65nm CMOS technology without excessive device voltage stress. Two on-chip transformers combined the outputs of four Class-D stages. At 1.95GHz the PA delivered +29.7dBm with a PAE of 26.6%. The 3dB bandwidth was 1.6GHz, representing state-of-the-art bandwidth for CMOS Class-D RF PAs. After one week of continuous operation, no performance degradation was noticed. The second design was based on the same Class-D stage, but combined eight amplifier stages by four on-chip transformers in 130nm CMOS to achieve a state-of-the-art output power of +32dBm for CMOS Class-D RF PAs. Both designs met the ACLR and modulation requirements without predistortion when amplifying uplink WCDMA and 20MHz LTE signals. The third outphasing design was based on two low-power Class-D stages in 90nm CMOS featuring a harmonic suppression technique, cancelling the third harmonic in the output spectrum which also improves drain efficiency. The proposed Class-D stage creates a voltage level of VDD/2 from a single supply voltage to shape the drain voltage, uses only digital circuits and eliminates the short-circuit current present in inverter-based Class-D stages. A single Class-D stage delivered +5.1dBm at 1.2V supply voltage with a drain efficiency and PAE of 73% and 59%, respectively. Two Class-D stages were connected to a PCB transformer to create an outphasing amplifier, which was linear enough to amplify EDGE and WCDMA signals without the need for predistortion. The fourth outphasing design was based on two Class-D stages connected to an on-chip transformer with peak power of +10dBm. It was used in the development of a behavioral model structure and model-based phase-only predistortion method suitable for outphasing amplifiers to compensate for both amplitude and phase mismatches. In measurements for EDGE and WCDMA signals, the predistorter improved the margin to the limits of the spectral mask and the ACLR by more than 12dB. Based on a similar approach, an amplifier model and predistortion method were developed and evaluated for the +32dBm Class-D PA design using a downlink WCDMA signal, where the ACLR was improved by 13.5dB. A least-squares phase predistortion method was developed and evaluated for the +30dBm Class-D PA design using WCDMA and LTE uplink signals, where the ACLR was improved by approximately 10dB.

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Sowlati, Hashjani Tirdad. "Class E power amplifiers for wireless communications". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ28305.pdf.

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29

Doyama, Jason. "Class E power amplifiers for wireless transceivers". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0015/MQ45854.pdf.

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30

Wisell, David. "Measurement Techniques for Characterization of Power Amplifiers". Doctoral thesis, Stockholm : KTH School of Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4566.

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31

Stacey, Craig D. "High power amplification with optical fibre amplifiers". Thesis, Heriot-Watt University, 2007. http://hdl.handle.net/10399/92.

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32

Rule, John Eric. "Gain and phase equalisation of power amplifiers". Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400154.

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33

Burrow, Stephen George. "Low power, high efficiency Class D amplifiers". Thesis, University of Bristol, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271779.

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34

FIGUEIREDO, TIAGO NASCIMENTO DE. "BROADBAND RF POWER AMPLIFIERS FOR MULTIBAND TRANSCEPTORS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=22900@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
Este trabalho descreve o desenvolvimento completo de um Amplificador de Potência de RF para Transceptores Multibanda. Em sua etapa inicial mostra um apanhado geral da teoria de todos os parâmetros relevantes para a medida de desempenho desses dispositivos, como potência, ganho e parâmetros de não linearidades. Em seguida são expostas as teorias básicas para o entendimento dos mecanismos para extração da máxima potência de um transistor, focando nos transistores de efeito de campo FET, incluindo a caracterização para regimes de alta potência. São apresentados os modos de operação de um amplificador de potência, focando nos chamados modos clássicos, dado que esses modos são convenientes para operação em banda larga. Para a correta operação de qualquer dispositivo que apresente ganho, a análise de estabilidade é apresentada com o procedimento de estabilização de transistores. A partir de todo o apanhado teórico, é desenvolvida uma metodologia de projeto de amplificadores de potência utilizando a ferramenta de simulação computacional Advanced Design System. Então, após toda a modelagem do amplificador, a construção e medidas são realizadas e boa concordância com a simulação foi obtida.
This work describes the full development of a RF Power Amplifier for Multiband Transceivers. In its initial stage shows an overview of the theory of all relevant parameters to measure the performance of these devices, like power, gain and nonlinearity parameters. Then it exposes the basic theories for the understanding of the mechanisms for extracting the maximum power of a transistor, focusing on field effect transistors FET, including characterization for regimes of high power. It presents the modes of operation of a power amplifier, focusing on so-called classical modes, since these modes are suitable for broadband operation. For proper operation of any device that presents gain, the stability analysis is presented with the stabilization procedure of transistors. From all theoretical basis, is developed a design methodology of power amplifiers using the computational simulation tool Advanced Design System. So after all the amp modeling, construction and measurements are performed and good agreement was obtained with the simulation.

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35

Xiao, Ming. "Novel predistortion techniques for RF power amplifiers". Thesis, University of Birmingham, 2009. http://etheses.bham.ac.uk//id/eprint/510/.

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As the mobile phone is an essential accessory for everyone nowadays, predistortion for the RF power amplifiers in mobile phone systems becomes more and more popular. Especially, new predistortions for power amplifiers with both nonlinearities and memory effects interest the researchers. In our thesis, novel predistortion techniques are presented for this purpose. Firstly, we improve the digital injection predistortion in the frequency domain. Secondly, we are the first authors to propose a novel predistortion, which combines digital LUT (Look-up Table) and injection. These techniques are applied to both two-tone tests and 16 QAM (Quadrature Amplitude Modulation) signals. The test power amplifiers vary from class A, inverse class E, to cascaded amplifier systems. Our experiments have demonstrated that these new predistortion techniques can reduce the upper and lower sideband third order intermodulation products in a two-tone test by 60 dB, or suppress the spectral regrowth by 40 dB and reduce the EVM (Error Vector Magnitude) down to 0.7% rms in 16 QAM signals, disregarding whether the tested power amplifiers or cascade amplifier systems exhibit significant nonlinearities and memory effects. i

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Arumilli, Gautham Venkat. "RF breakdown effects in microwave power amplifiers". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/45612.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 95-98).
Electrical stresses in the transistors of high-efficiency switching power amplifiers can lead to hot-electron-induced "breakdown" in these devices. This thesis explores issues related to breakdown in the Transcom TC2571 PHEMT, and the effects this has on the Draper Laboratory 2.3 GHz microwave power amplifier in which the transistor is used. Characterization of breakdown was performed under DC and RF drive conditions, and shows the surprising role of impact ionization at low temperatures in DC off-state breakdown, as well as the apparent prevalence of on-state breakdown under RF drive. DC characterization shows that breakdown walkout and recovery both proceed more quickly at higher temperatures, and also shows that breakdown stress might lead to the permanent creation of traps that degrade breakdown voltage. Walkout under RF drive decreases amplifier gain at lower levels of RF input drive, but appears to have no negative effect on amplifier saturated output power. The use of temperature-compensated input drive and a diode to clamp negative gate voltage swing are also explored as circuit design techniques that can mitigate device degradation due to breakdown stress.
by Gautham Venkat Arumilli.
M.Eng.

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Godoy, Philip (Philip Andrew). "Techniques for high-efficiency outphasing power amplifiers". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68486.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 171-177).
A trade-off between linearity and efficiency exists in conventional power amplifiers (PAs). The outphase amplifying concept overcomes this trade-off by enabling the use of high efficiency, non-linear power amplifiers for linear amplification. However, the efficiency improvement is limited by the efficiency of the output power combiner. This thesis investigates techniques to overcome this efficiency limit while maintaining sufficient linearity. Two techniques are proposed. The first technique is called the outphasing energy recovery amplifier (OPERA), which recovers the normally wasted power back to the power supply and utilizes a resistance compression network for improved linearity. A 48-MHz, 20-W prototype OPERA system was built which demonstrates more than 2x higher efficiency than the standard outphasing system for a 16-QAM signal. The second technique to improve the efficiency of the outphasing system is asymmetric multilevel outphasing (AMO) modulation. In the AMO system, the amplitude for each of the two outphased PAs can switch independently among multiple discrete levels, significantly reducing the energy lost in the power combiner. Three different AMO prototypes were built, each of which demonstrate between 2x-3x efficiency improvement compared to the standard outphasing system. A 2.4-GHz, 500- mW prototype made in a 65-nm CMOS process achieves an average system efficiency of 28.7% for a 20-MHz 64-QAM signal. To the author's best knowledge, this is the highest reported efficiency for a CMOS PA in the 2-2.7 GHz range for signal bandwidths greater than 10 MHz.
by Philip Andrew Godoy.
Ph.D.

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McIver, Stuart Roderick Arthur. "High power LDMOS L-band radar amplifiers". Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4092.

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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: The thesis details the design, construction and experimental evaluation of 30W, 35W and 250W L-Band LDMOS Radar amplifiers. Each amplifier module contains an integrated high speed power supply in order to optimize RF pulse repeatability and to improve radar MTI factor (Moving Target Indication.) As part of the work, a pulsed RF measurement system for measuring the dynamic I-V curves of a power FET was developed. Work was also done on low impedance S-parameter measurement test fixtures for the characterisation of power FETs. These measurement systems generated design information which was used in the development of the L-Band power amplifiers
AFRIKAANSE OPSOMMING: Hierdie tesis beskryf die ontwerp, bou en experimentele evaluering van „n 30W, 35W en 250W L-band LDMOS radarversterker. Elke versterker bevat ook „n geintegreerde hoë-spoed kragbron om optimum RF pulsherhaalbaarheid te verseker en die radar se „MTI (Moving Target Indication)‟ te verbeter. „n RF-pulsmetingstelsel is ook ontwikkel om die dinamiese I-V kurwes van „n hoë-krag FET te meet. Verder is daar ook gewerk aan „n toetsopstelling vir lae-impedansie S-parameters om hoë-krag FETs te karakteriseer. Hierdie toetsopstelling is gebruik om ontwerpsdata te genereer wat gebruik is in die ontwerp van die L-band kragversterkers.

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Nizamuddin, Muhammad Ali. "Predistortion for Nonlinear Power Amplifiers with Memory". Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/36184.

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The fusion of voice and data applications, along with the demand for high data-rate applications such as video-on-demand, is making radio frequency (RF) spectrum an increasingly expensive commodity for current and future communications. Although bandwidth-efficient digital modulation alleviates part of the problem by requiring a minimal use of spectral resources, they put an extra design burden on RF engineers. RF transmitters and power amplifiers account for more than half the total maintenance cost of a base-station, while occupying nearly the same portion of space. Therefore, power amplifiers become a bottleneck for digital systems in terms of space and power consumption. However, power-efficient use of the amplifiers, although desirable, is extremely detrimental to end-to-end performance due to the very high peak-to-average power ratios of modulations that are used today. In order to reduce distortion while maintaining high power conversion efficiency in a power amplifier, linearization schemes are needed. In addition, significant frequency-dependent Memory Effects result in high power amplifiers operating on wideband signals. Therefore, these effects need to be considered during any attempt to minimize amplifier distortion.

In this thesis, we present two schemes to cancel nonlinear distortion of a power amplifier, along with its memory effects and results for one of the schemes. The results highlight the fact that in the presence of significant memory effects, cancellation of these effects is necessary to achieve reasonable improvement in performance through linearization. We focus on predistortive schemes due to their digital- friendly structure and simple implementation. The operating environment consists of a multi-carrier W-CDMA signal. All of the studies are performed using numerical simulation on MATLAB and Agilent's Advanced Design System (ADS).

Master of Science

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Muthukrishnan, Swaminathan. "ESD Protected SiGe HBT RFIC Power Amplifiers". Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/31705.

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Over the last few decades, the susceptibility of integrated circuits to electrostatic discharge (ESD) induced damages has justified the use of dedicated on-chip protection circuits. Design of robust protection circuits remains a challenging task because ESD failure mechanisms have become more acute as device dimensions continue to shrink. A lack of understanding of the ESD phenomena coupled with the increased sensitivity of smaller devices and time-to-market demands has led to a trial-and-error approach to ESD-protected circuit design. Improved analysis capabilities and a systematic design approach are essential to accomplish the challenging task of providing adequate protection to core circuit(s). The design of ESD protection circuitry for RFIC's has been relatively slow to evolve, compared to their digital counterparts, and is now emerging as a new design challenge in RF and high-speed mixed-signal IC development. Sub-circuits which are not embedded in a single System-on-Chip (SOC), such as RF Power amplifiers (PAs), are of particular concern as they are more susceptible to the various ESD events. This thesis presents the development of integrated ESD protection circuitry for two RFIC Power Amplifier designs. A prototype PA for 2.4 GHz Wireless Local Area Network (WLAN) applications was redesigned to provide protection to the RF input and the PA Control pins. A relatively new technique known as the L-C tank approach was used to protect the RFinput while a standard diode ring approach was used to protect the control line. The protection techniques studied were subsequently extended to a completely protected three-stage PA targeting 1.9 GHz Digitally Enhanced Cordless Telephone (DECT) applications. An on-chip shunt-L-series-C input matching network was used to provide ESD protection to the input pin of the DECT PA. A much more area efficient (as compared to the diode ring technique) Zener diode approach was used to protect the control and signal lines. The PA's RF performance was virtually unaffected by the addition of the protection circuits. Both PAs were designed in a commercially available 0.5 Ã¬m SiGe-HBT process. The partially protected WLAN PA was fabricated and packaged in a 3mm x 3mm Fine Pitch Quad Flat Package FQFP-N 12 Lead package and had a measured ESD protection rating of Â± 1kV standard Human Body Model (HBM) ESD test. The simulated DECT PA demonstrated +1.5kV/-4kV HBM performance.
Master of Science

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41

Hall, Andrew D. "Broadband, low-noise and power microwave amplifiers". Master's thesis, University of Cape Town, 1986. http://hdl.handle.net/11427/17613.

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The design of Broadband, Low-Noise and Power Microwave Amplifiers using microstrip softboard technology is investigated. The software program TOUCHSTONE (TM) by EEsof is used extensively as a basic design tool. The characterisation of the GaAs Field Effect Transistors, used for the amplifiers, is carried out. These characterisations are then used by the program in its circuit analysis. A determination of the validity of using the manufacturer's data, for the designs, is determined by comparing it to the measured data. Source-Pull and Load-Pull measurements were performed for the Power GaAs FET characterisation. The noise-parameter device characterisation is carried out in a similar way to that for Load-Pull data. Each amplifier required final tuning adjustments in order to peak the performances. The Broadband Maximum Gain Amplifier had a 10 ± 1.5dB gain over a bandwidth from 2- to 6-GHz. The Low-Noise amplifier achieved 5dB Noise-Figure and 5.4 ± 1. 4dB gain over the 2- to 6-GHz band. The Power amplifier Output Power was 390mW over the 3.7- to 4.2-GHz band. Techniques of broadband matching are investigated, with Double-Stub matching producing the widest bandwidth. A literature survey is presented on aspects of broadband microwave amplifiers, as well as a survey on Computer-aided-design at microwave frequencies and techniques of Large-Signal Transistor characterisation.

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42

Glaros, Konstantinos N. "Low-power pulse oximetry and transimpedance amplifiers". Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/9480.

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This work focuses on the design of low-power fully-integrated pulse oximeter front-ends and transimpedance amplifiers. Mathematical modelling and numerical simulations are employed to systematically quantify the trade-offs involved in the design of such a front-end and investigate the specific challenges arising from the requirements for low- power and full integration. The response speed, stability, power consumption and noise characteristics of the front-end's transimpedance amplifier are identified as significant points of interest. The performance of several transimpedance amplifier topologies is investigated. Topologies based on switched integration of the input are shown to be advantageous and employed in the design of a mixed-signal pulse oximeter front-end which was fabricated in the AMS 0:35 m technology. Extensive electrical and physiological measurements are reported showing that the proposed front-end can achieve LED power consumptions below 400 W and a total power consumption of less than 1 mW with a mean signal-to-noise ratio exceeding 39 dB at the detector. This performance is among the best ever reported and an order of magnitude better than most commercial pulse oximeters. Ways to lower this power consumption even further are identified. This work also reports on a novel self-biased photoreceptor (transimpedance amplifier) topology. A detailed comparison with previous state-of-the-art designs is carried out that provides new, useful insights on the photoreceptors' performance. The proposed design is concluded to be beneficial for applications where extremely low power and fast settling are of high significance.

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López, Néstor David. "High-efficiency power amplifiers for linear transmitters". Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3303889.

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44

Aboukarr, Bakri Carleton University Dissertation Engineering Electrical. "Adaptive predistortion linearization of nonlinear power amplifiers". Ottawa, 1990.

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45

Mishra, Chinmaya. "Design and implementation of low power multistage amplifiers and high frequency distributed amplifiers". Texas A&M University, 2004. http://hdl.handle.net/1969.1/2775.

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The advancement in integrated circuit (IC) technology has resulted in scaling down of device sizes and supply voltages without proportionally scaling down the threshold voltage of the MOS transistor. This, coupled with the increasing demand for low power, portable, battery-operated electronic devices, like mobile phones, and laptops provides the impetus for further research towards achieving higher integration on chip and low power consumption. High gain, wide bandwidth amplifiers driving large capacitive loads serve as error amplifiers in low-voltage low drop out regulators in portable devices. This demands low power, low area, and frequency-compensated multistage amplifiers capable of driving large capacitive loads. The first part of the research proposes two power and area efficient frequency compensation schemes: Single Miller Capacitor Compensation (SMC) and Single Miller Capacitor Feedforward Compensation (SMFFC), for multistage amplifiers driving large capacitive loads. The designs have been implemented in a 0.5??m CMOS process. Experimental results show that the SMC and SMFFC amplifiers achieve gain-bandwidth products of 4.6MHz and 9MHz, respectively, when driving a load of 25Kδ/120pF. Each amplifier operates from a ??1V supply, dissipates less than 0.42mW of power and occupies less than 0.02mm2 of silicon area. The inception of the latest IEEE standard like IEEE 802.16 wireless metropolitan area network (WMAN) for 10 -66 GHz range demands wide band amplifiers operating at high frequencies to serve as front-end circuits (e.g. low noise amplifier) in such receiver architectures. Devices used in cascade (multistage amplifiers) can be used to increase the gain but it is achieved at an expense of bandwidth. Distributing the capacitance associated with the input and the output of the device over a ladder structure (which is periodic), rather than considering it to be lumped can achieve an extension of bandwidth without sacrificing gain. This concept which is also known as distributed amplification has been explored in the second part of the research. This work proposes certain guidelines for the design of distributed low noise amplifiers operating at very high frequencies. Noise analysis of the distributed amplifier with real transmission lines is introduced. The analysis for gain and noise figure is verified with simulation results from a 5-stage distributed amplifier implemented in a 0.18??m CMOS process.

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Nagarajan, Preeti. "Design of Power Amplifier Test Signals with a User-Defined Multisine". Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4454/.

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Cellular radio communication involves wireless transmission and reception of signals at radio frequencies (RF). Base stations house equipment critical to the transmission and reception of signals. Power amplifier (PA) is a crucial element in base station assembly. PAs are expensive, take up space and dissipate heat. Of all the elements in the base station, it is difficult to design and operate a power amplifier. New designs of power amplifiers are constantly tested. One of the most important components required to perform this test successfully is a circuit simulator model of an entire communication system that generates a standard test signal. Standard test signals 524,288 data points in length require 1080 hours to complete one test of a PA model. In order to reduce the time taken to complete one test, a 'simulated test signal,' was generated. The objective of this study is to develop an algorithm to generate this 'simulated' test signal such that its characteristics match that of the 'standard' test signal.

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Jiang, Xufeng. "Envelope-tracking power supplies for RF power amplifiers in portable applications". Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3256446.

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48

Bendig, Rudi Matthew. "AC Power Combining Strategy with Application to Efficient Linear Power Amplifiers". DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1220.

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With the ongoing push for wireless systems to accommodate more users and support higher data rates more efficient modulation schemes have been created that are more advanced than simple FM and AM modulation used for radio broadcasting. These modulation schemes, such as orthogonal frequency division multiplexing (OFDM), suffer from high peak to average power ratios. Standard Class A and Class AB amplifiers cannot simultaneously achieve good linearity and efficiency, and therefore there has been an increase in the development of new topologies to combat this issue. Common features to these circuits is power combining of two or more separate transistors. In this work, we consider various ways of two-source power combining and identify four topologies of interest. We notice that linear power-efficient amplifiers reported to date are based upon two of the identified combining strategies. We believe that no amplifiers have been reported that leverage the other two alternatives. This work produces a fully-functional amplifier based on one of these alternatives. The prototypes are intended to serve as concept verification of the architecture and hence are implemented at lower (1 MHz) frequencies.

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Feng, Cheng-Chuan. "Ku-band high power amplifier system functionality and operation". Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA236912.

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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 1990.
Thesis Advisor(s): Lee, Hung-Mou. Second Reader: Ewing, Gerald D. "June 1990." Description based on signature page. DTIC Identifiers: Power amplifiers, high power, ku band. Author(s) subject terms: High power amplifier system, RF amplifier unit, control unit, high voltage supply unit, cooling unit, modulation unit, system operation, maintenance and troubleshooting procedures. Includes bibliographical references (p. 117). Also available online.

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Brand, Konrad Frederik. "The experimental design and characterisation of Doherty power amplifiers". Thesis, Link to the online version, 2006. http://hdl.handle.net/10019.1/2594.

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Tesi sul tema "Power amplifiers"

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