Dissertations / Theses: 'PHEME'

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Basson, Willem Diederick. "Improving Grapheme-based speech recognition through P2G transliteration / W.D. Basson." Thesis, North-West University, 2014. http://hdl.handle.net/10394/11068.

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Grapheme-based speech recognition systems are faster to develop, but typically do not reach the same level of performance as phoneme-based systems. Using Afrikaans speech recognition as a case study, we first analyse the reasons for the discrepancy in performance, before introducing a technique for improving the performance of standard grapheme-based systems. It is found that by handling a relatively small number of irregular words through phoneme-to-grapheme (P2G) transliteration – transforming the original orthography of irregular words to an ‘idealised’ orthography – grapheme-based accuracy can be improved. An analysis of speech recognition accuracy based on word categories shows that P2G transliteration succeeds in improving certain word categories in which grapheme-based systems typically perform poorly, and that the problematic categories can be identified prior to system development. An evaluation is offered of when category-based P2G transliteration is beneficial and methods to implement the technique in practice are discussed. Comparative results are obtained for a second language (Vietnamese) in order to determine whether the technique can be generalised.
MSc (Computer Science) North-West University, Vaal Triangle Campus, 2014

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Casadio, Ylenia Silvia. "Biodegradable PHEMA-based biomaterials." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0173.

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[Truncated abstract] The synthetic hydrogel poly(2-hydroxyethyl methacrylate) (PHEMA) has been used as a biocompatible biomaterial in ocular devices, such as soft contact lenses, intraocular lenses and an artificial cornea. Due to its favourable properties as an already established (but non-biodegradable) biomaterial, PHEMA is an interesting candidate for use as a material for scaffolds in tissue engineering. A tenant of tissue engineering scaffolds is obtaining the appropriate porous morphology to allow for successful cellular attachment and support. PHEMA hydrogels exhibit varied morphological features, which range from non-porous (homogeneous) to macroporous (heterogeneous) and can be readily obtained by fine-tuning the polymerisation conditions. A desirable feature for matrices that are to be used as tissue supports is the ability to biodegrade in a biological environment. This thesis describes the preparation and enzymatic biodegradation behaviour of novel porous PHEMA hydrogels that have been crosslinked with biodegradable peptide-based crosslinking agents. Peptide-based crosslinking agents were designed to contain two terminal polymerisable groups flanking an internal biodegradable backbone. This backbone was specifically designed to be targeted by the proteolytic enzyme papain. The general design template allowed for the development of a synthetic methodology that was readily implemented for the production of a range of olefin-peptide conjugates. A suite of olefin-peptide conjugates of general structure I were synthesised, characterised and further tested with papain to determine their biodegradation properties. ... The second strategy for producing bioresorbable degradation fragments involved the incorporation of the highly hydrophilic comonomer, poly(ethylene glycol) PEG into the PHEMA backbone. The addition of PEG to PHEMA resulted in the formation of homogeneous hydrogels that had an improved hydrophilicity compared to their heterogeneous PHEMA counterparts. The synthetic conditions for the preparation of PHEMA and PHEMA-co-PEG hydrogels by photoinitiated polymerisation were thoroughly investigated. It was found that the pore morphology and general properties (non-porous to macroporous) of these hydrogels could be controlled by the appropriate choice of polymerisation conditions. The hydrogels were characterised by scanning electron microscopy, thermal gravimetric analysis and differential scanning calorimetry. The peptide-based crosslinking agents were successfully co-polymerised with the HEMA and PEGMA via photoinitiated polymerisation to provide a range of PHEMA and PHEMA-co-PEG hydrogels that displayed both homogeneous and heterogeneous hydrogel properties. The final crosslinked hydrogels were characterised by scanning electron microscopy and were subjected to enzymatic hydrolysis. The PHEMA-peptide conjugate hydrogels proved to be biodegradable, with degradation behaviour dependent on the hydrogel formulation and the length of the peptide-based crosslinking agent.

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Bennett, Darrell Jonathan. "Properties of crosslinked phema hydrogels /." Title page, contents and introduction only, 1991. http://web4.library.adelaide.edu.au/theses/09PH/09phb4713.pdf.

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Haris, Norshakila. "Three-dimensional multilayer integration and characterisation of CPW MMIC components for future wireless communications." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/threedimensional-multilayer-integration-and-characterisation-of-cpw-mmic-components-for-future-wireless-communications(89ddea33-4de2-43ba-b8dc-dbc032b868e7).html.

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The development of monolithic microwave integrated circuits (MMICs) has enabled the expansion of multiple circuit elements on a single piece of semiconductor, enclosed in a package with connecting leads. Attributable to the widespread use of wireless circuits and sub-systems, MMICs meet stringent demands for smaller chip area, low loss and low cost. These require highly integrated MMICs with compact features. This thesis provides valuable insight into the design of compact multifunctional MMICs using three-dimensional (3-D) multilayer technology. The proposed technology offers compact, hence low-cost solutions, where all active and passive components are fabricated vertically on the same substrate and no expensive via hole or backside processing is required. The substrate used in this work contains pre-fabricated 0.5 µm pseudomorphic High Electron Mobility Transistor (pHEMT) GaAs active devices. The performances of the uncommitted and committed pHEMTs are compared in terms of their DC, small-signal and large-signal RF measurements and modelling results. Committed pHEMT refers to the pHEMT that is connected to multilayer circuit, whereas uncommitted pHEMT is not. The effect of integrating committed pHEMTs with multilayer passive components is studied and the suitability of the multilayer fabrication processing is assessed. Using this technology, two pHEMT Schottky diodes with 120 µm and 200 µm gate widths are designed, fabricated and extensively characterised by I-V, C-V and S-parameter measurements. The information gained from the measurements is then used to extract all unknown equivalent circuit model parameters using high-frequency on-wafer microwave probing. The measured results showed good agreement with the modelled ones over the frequency range up to 40 GHz. Preliminary demonstrations of the use of these pHEMT Schottky diodes in microwave limiter and detector circuit applications are also discussed, showing promising results. Finally, the implementation of 3-D multilayer technology is shown for the first time in single-pole single-throw (SPST) and single-pole double-throw (SPDT) switches design by utilising the pre-fabricated pHEMTs. The design and analysis of the switches are demonstrated first through simulation using TriQuint's Own Model - Level 3 (TOM3). Three optimised SPST and SPDT pHEMT switching circuits which can address applications ranging from L to X bands are successfully fabricated and tested. The performance of the pHEMT switches is comparable to those of the current state-of-the-art, while simultaneously offering compact circuits with the advantages of integration with other MMIC components. All works reported in this thesis should facilitate foundry design engineers towards further development of 3-D multilayer technology.

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Béland, Paul. "Millimeter-wave noise characterization of PHEMT devices." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq26300.pdf.

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Seng, Hing Weng. "Exploitation of phemt in microwave power limiters." Thesis, University of Manchester, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.594759.

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This thesis describes the design and the study of implementing microwave power limiters with Gallium Arsenide (GaAs) pseudomorphic high electron mobility transistors (PHEMTs). Circuits were fabricated in microwave integrated circuits (MICs) and monolithic microwave integrated circuits (MMICs) format, tested for performance at 2GHz and 10GHz respectively. The majority of microwave power limiters offered in the current market are based on the p-i-n or PIN diode for protection. Generally in the RF industries, very high power applications still utilize solid-state devices such as T-R tubes for power limiters due to their electrical robustness. However, with the ever growing urge for product improvements and the maturity of MMICs, the lack of integration of the PIN diodes with MMICs calls for an investigation into alternate approaches in power limiter design. Many switching applications in MMICs are implemented using pHEMTs in both series and shunt orientation. The Schottky diode is the favoured choice for microwave power detection purposes. The microwave power limiter approach suggested in this thesis utilizes the pHEMTs as a voltage controlled attenuator in conjunction with a Schottky diode based detector as the control voltage supplier. The MICs or hybrids have been designed using Avago's general purpose pHEMT ATF-35143 as the major element in the voltage controlled switch attenuator sub circuit. The voltage controlled attenuator is supplied with a control voltage from a detector or combination of detector and external bias, depending on the switch's configuration. Avago's Schottky diode HSMS-8101 was used as the detector diode in the power detecting sub circuit. The MMICs were designed using the FD05 O.251lm pHEMT process design kit from Filtronic Compound semiconductor PLC, Newton Aycliffe, Durham, United Kingdom. The pHEMT epi-layers were grown by molecular beam epitaxy on 150mm semi-insulating substrates, featuring O.51lm gate length and 50llm gate width. It is found that larger device provides lower loss but lower isolation. The Schottky diode used in fabricated MMICs is a single gate and 20llm wide device. In the design approach adopted here, the junction of the voltage controlled attenuator and detector is realized using aT-junction. Other methods used include the proximity coupler and capacitive power divider network. Each coupling method finds merit depending on the switch configuration of the attenuator. Eight types of MIC limiters were made, including the single series switch, double series switch, single shunt switch, double shunt switch, series-shunt switch, shunt-series switch, n-switch and tee-switch limiters. The lowest insertion loss achieved was -O.34dB while the isolation is 8dB, delivered by the single shunt switch, measured at 2GHz. The best isolation measured was 20dB, seen in the tee-switch and the double series switch limiters. From the fabricated MMIC limiters, 3.03dB insertion loss and 15dB isolation is provided by the single series switch limiter. While the double series switch limiter is seen to deliver 5.25dB insertion loss and 25dB isolation. Both MMIC limiters exhibit the same limiting threshold level at 10dBm on X-band.

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Jasper, David Brian. "RF pHEMT Switch Model for Multiband Cell Phone Circuits." NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-11032004-220504/.

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Simulation of Radio Frequency Switches used in the cellular phone industry is the main focus of this study. The RF pHEMT?s used in an antenna switch for multiband cell phone circuits requires the use of an accurate model during simulation of the RF system. The pHEMT model extracted in this study utilizes theoretical methods within the extraction software and an analysis of simulated data and measured data. This study describes the techniques of calibration, model extraction, and data analysis.

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Martins, Everson. "Projeto de misturador com topologia celula de Gilbert utilizando pHEMT." [s.n.], 2002. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260267.

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Orientador : Jacobus Willibrordus Swart
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Doutorado

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Mat, Jubadi Warsuzarina. "Modelling of advanced submicron gate InGaAs/InAlAs pHEMTs and RTD devices for very high frequency applications." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/modelling-of-advanced-submicron-gate-ingaasinalas-phemts-and-rtd-devices-for-very-high-frequency-applications(4688a951-f235-4720-93e4-441eabcce44a).html.

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InP-based InAlAs/InGaAs pseudomorphic High Electron Mobility Transistors (pHEMTs) have shown outstanding performance; this makes them prominent in high frequency mm-wave and submillimeter-wave applications. However, conventional InGaAs/InAlAs pHEMTs have major drawbacks, i.e., very low breakdown voltage and high gate leakage current. These disadvantages degrade device performance, especially in Monolithic Microwave Integrated Circuit (MMIC) low noise amplifiers (LNAs). The optimisation of InAlAs/InGaAs epilayer structures through advanced bandgap engineering offers a key solution to the problem. Concurrently, device modelling plays a vital role in the design and analysis of pHEMT devices and circuit performance. In this research, two-dimensional (2D) physical modelling of 1 m and sub-micro metre gate length strained channel InAlAs/InGaAs/InP pHEMTs has been developed, in ATLAS Silvaco. All modelled devices were optimised and validated by experimental devices, which were fabricated at the University of Manchester. An underlying device physics insight is gained, i.e., the effect of changes to the device's physical structure, theoretical concepts and its general operation, and a reliable pHEMT model is obtained. The kink anomalies in the I-V characteristics were reproduced. The 2D simulation results demonstrate an outstanding agreement with measured DC and RF characteristics. The aim of developing linear and non-linear models for sub-micro metre transistors and their implementation in MMIC LNA design is achieved with the 0.25 m In0.7Ga0.3As/In0.52Al0.48As/InP pHEMT. An accurate method for the extraction of empirical models for the fabricated active devices has been developed, and optimised using the Advance Design System (ADS) software. The results demonstrate excellent agreement between experimental and modelled DC and RF data. Precise models for MMIC passive devices are also obtained, and incorporated in the proposed design for a single- and double-stage MMIC LNAs at C- and X-band frequencies. The single-stage LNA is designed to achieve a maximum gain ranging from 9 to 13 dB over the band of operation, while the gain is increased to between 20 dB and 26 dB for the double-stage LNA designs. A noise figure of less than 1.2 dB and 2 dB is expected, for the C- and X-band LNAs respectively, while retaining stability across all frequency bands. Although the RF performance of pHEMT is being vigorously pushed towards the terahertz (THz) region, novel devices such as the Resonant Tunnelling Diode (RTD) are needed to support future ultra-high-speed, high-frequency applications. Hence, the study of physical modelling is extended to quantum modelling of an advanced In0.8Ga0.2As/AlAs RTD device. The aim is to effectively model both large-size and submicron RTDs, using Silvaco's ATLAS software to reproduce the peak current density, peak-to-valley-current ratio (PVCR), and negative differential resistance (NDR) voltage range. The physical modelling for the RTD devices is optimised to achieve an excellent match with the fabricated RTD devices; variations in the spacer thickness, barrier thickness, quantum well thickness and doping concentration are included.

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Lorenzetti, Solange Gubbelini. ""Obtenção dos sistemas bioconjugados Crotoxina/PEBD-g-Phema e Crotoxina/PCL"." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-08062007-132650/.

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A finalidade deste trabalho de pesquisa foi a obtenção de matrizes poliméricas imobilizadas com a crotoxina, proveniente do veneno bruto de cascavel. Foram obtidas duas matrizes: (a) copolímero de enxerto para a imobilização da crotoxina, (b) micro-esferas de épisolon-policaprolactona (PCL) com crotoxina encapsulada. A crotoxina, proveniente da serpente Crotalus durissus terrificus (cascavel da América do Sul), após a sua purificação, foi caracterizada bioquímica e biologicamente. O resultado da avaliação da dose letal média (DL50) da toxina foi de 0,09mg/Kg de animal. O teste de citotoxicidade apresentou resultados semelhantes entre as células tumorais e os respectivos controles das células normais. Copolímeros de polietileno de baixa densidade enxertado com poli(metacrilato de 2-hidroxietila) (PEBD-g-PHEMA) foram utilizados como suportes para a imobilização química da crotoxina purificada. Para tal utilizou-se o polietileno de baixa densidade (PEBD) juntamente com o monômero hidrofílico metacrilato de 2-hidroxietila (HEMA). Os copolímeros foram obtidos via radiação ionizante, em fonte de cobalto 60 (60Co), e apresentaram graus de enxertia que variaram de 2 a 50%. Na caracterização por espectroscopia em infravermelho (ATR) observou-se os grupos funcionais principais do copolímero, em relação ao polímero base e PHEMA formado na irradiação. No perfil espectroscópico do copolímero estavam presentes bandas atribuídas aos grupos C=O (carbonila) e OH (hidroxil), provenientes do homopolímero PHEMA. As micrografias do MEV do PEBD apresentaram superfícies lisas, enquanto que PEBD-g-PHEMA com alto grau de enxertia (32 %) revelou superfície rugosa devido à presença de PHEMA. O copolímero foi caracterizado fisicamente com o teste de hidrofilicidade, no qual o conteúdo de água foi determinado gravimetricamente. Com o coeficiente de difusão obtido pôde-se notar vii que a partir de 30 % de enxertia o copolímero torna-se menos hidrofílico, devido ao aumento das ligações cruzadas entre as cadeias de PHEMA. O teste de citotoxicidade revelou que PEBD-g-PHEMA pode ser utilizado como biomaterial. O copolímero imobilizado, crotoxina encapsulada e a crotoxina livre foram avaliados in vivo em camundongos da linhagem C3H. Durante 20 dias foram observados alterações de peso e comportamento, além das funções motoras. Os resultados demonstraram que o grupo injetado com crotoxina teve uma perda de peso maior do que os demais grupos. Concluindo, a crotoxina imobilizada nos copolímeros poderia ser utilizada pela sua ação catalítica foslipásica, na hidrólise dos fosfolipídeos presente nas lipoproteínas de baixa densidade (LDL) do soro humano. Por outro lado, a crotoxina encapsulada nas micro-esferas de poli(épsilon-caprolactona) (PCL) poderia ser utilizada como sistema de liberação dirigida (local) da crotoxina, destinada a terapia tumoral.
The aim of the work was the obtainment of polymeric matrices immobilized with crotoxin purified from crude venom of rattle snake. A matrix was processed by gamma irradiation by the grafting of a hydrogel onto a polymeric film which resulted in a copolymer for the chemical immobilization of crotoxin. The second matrix was attainned by the entrapment of crotoxin in microspheres of epsilon-polycaprolactone. After the purification, the crotoxin proceeding from the snake Crotalus durissus terrificus was evaluated biochemical and biologically. The letal dose (LD50%) of the toxin was 0.09/kg animal. The test of cytotoxicity not revealed any significant difference between the tumoral cells and the respective normal control cells in culture. Grafting copolymers were used as scaffold for the chemical immobilization of the purified crotoxin. For this purpose the low density polyethylene (LDPE) and the hydrophilic monomer 2-hydroxy-ethyl-methacrylate (HEMA) were copolymerized in a 60Co source. The copolymers (LDPE-g-PHEMA) showed grafting levels in the range of 2 and 50 %. In the infrared spectroscopy analysis (FTIR-ATR) it was observed in the copolymer, carbonyl groups (C=O) and hydroxyl groups OH due to the grafting of PHEMA. The MEV micrographies showed a smooth surface for the virgin LDPE and a rough surface for the LDPE-g-PHEMA, owing to the presence of grafted PHEMA. The hydrophilicity was observed by the determination of water content in the copolymer after immersion in water. By the diffusion coefficient it was noted that from 30 % grafting degree, the copolymers become less hydrophilic due to the crosslinking increase among the chains in PHEMA. The biocompatibility of the LDPE-g-PHEMA was proved by the cytoxicity test. At the end, the immobilized copolymer, the entraped crotoxin and the free crotoxin was tested in vivo. During 20 days, C3H strain mouses were observed in ix their weight, behavior and motor changes. The results demonstrated that the group injected with crotoxin had visible loss of weight higher than the other groups. It was concluded that, potentially the immobilized crotoxin could be used by its catalitic phospholipase action, possibily for the hydrolysis of phopholipids present in human serum low density lipoproteins (LDL). By the other side, the entraped crotoxin in the microspheres of epsilon-polycaprolactone could be employed in the managed drug delivered system for the tumoral therapy.

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SILVA, CLAUMIR SARZEDA DA. "PHEMT BALANCED PARAMETRIC FREQUENCY DIVIDER BY TWO FOR ELECTRONIC DEFENSE RECEIVERS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=15236@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
Este trabalho aborda o desenvolvimento de divisores de freqüência por dois paramétricos balanceados a PHEMT, tendo, como motivação, seu emprego como conversores de freqüência em receptores digitais de Defesa Eletrônica. Estes dispositivos têm como características importantes a simplicidade de projeto, um número reduzido de componentes, a possibilidade de integração em circuitos monolíticos de microondas (MMIC), coerência de fase, banda de operação larga, resposta a sinal pulsado muito boa, supressão de harmônicos boa, insensibilidade a variações térmicas e ruído de fase baixo. Uma metodologia de projeto passo a passo é proposta, norteada pela obtenção de dispositivos com ganho máximo (ou perdas mínimas) e banda de operação maximizada. Duas configurações de circuito são consideradas: com ressoadores em paralelo (linhas acopladas) e em série. A caracterização dos divisores é realizada por meio de simulação e experimentalmente. Por fim, uma análise comparativa com a literatura disponível é apresentada, mostrando que alguns dos circuitos desenvolvidos e realizados alcançaram melhor desempenho.
This work assesses the development of PHEMT balanced parametric frequency dividers by two, intended for application as frequency converters on Electronic Defense digital receivers. The main characteristics of these devices are design simplicity, reduced number of components, possibility of integration in MMIC, phase coherence, wide bandwidth, very good pulse response, good harmonic suppression, insensitivity to thermal variations and low phase noise. A step-by-step design methodology is proposed, guide by maximum gain (or minimum loss) and maximized band device requirements. Two circuit topologies are considered: with either parallel (coupled lines) or series resonators. The characterization of the dividers is performed both through simulation and experimentally. Finally, a comparative analysis against literature results is presented, evidencing that some of the developed circuits achieve better performance.

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LORENZETTI, SOLANGE G. "Obtenção dos sistemas bioconjugados crotoxina/PEBD-g-PHEMA e crotoxina/PCL." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11447.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Reinholm, Sanna. "Fenotypning med Phene Plate system av koagulas-negativa stafylokocker isolerade från centrala venkatetrar." Thesis, Örebro universitet, Hälsoakademin, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-11039.

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Koagulas-negativa stafylokocker (KNS) klassas som en viktig del av hudens normalflora. Vid skador på hudens barriär som en inläggning av centrala venkatetrar (CVK) innebär kan dock KNS få tillträde till normalt sterila lokaler där de kan orsaka infektion. Vid utodling av borttagna CVK från patienter resistensbestäms bara några enstaka kolonier vilket gör det lätt att missa förekomst av flera olika stafylokock-kloner. Syftet med studien var att undersöka hur ofta en eller flera olika KNS-kloner förekommer på CVK från patienter, samt om det förekommer gemensamma kloner av KNS på CVK från olika patienter. Kolonier från CVK prov analyserades med den biokemiska fingerprintingmetoden Phene Plate-system (PhP). Resultatet visade 37 stycken CVK prov innehållande en klon, 23 stycken prov där det fanns 2 separata kloner, samt 6 prov med 3 kloner. Jämförelsen av kolonier ur prov från olika patienter resulterade i kluster med många gemensamma PhP-typer. I de 3 största klustren fanns 31, 15, respektive 8 kolonier representerande olika patienter. Den betydande andelen polyklonala CVK prov leder till risken att missa en mer resistent klon vilket då kan få konsekvensen felaktig antibiotikabehandling av patient. Att många patientprov hade en gemensam KNS-klon tyder på spridning av speciellt virulenta stammar inom sjukhus.

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Grenik, Elizabeth Monica. "Chemical Modification of PHEMA to Create an Improved Bioactive Biomaterial for Regenerative Applications." Thesis, Curtin University, 2016. http://hdl.handle.net/20.500.11937/49779.

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Heparan sulfate (HS) and RGD were immobilised on porous 3D poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels. Significantly improved adhesion and proliferation of fibroblasts and myoblasts was demonstrated after the covalent immobilisation of the biomolecules. The best cell behaviour was observed on the hydrogels with HS which enhanced myoblast differentiation. This was likely due to the improved cell organisation from cell-hydrogel interactions. The improved cell behaviour on the modified hydrogels showed potential for tissue regeneration.

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Sadeghi, Mohammadreza. "Highly sensitive nano Tesla quantum well Hall Effect integrated circuits using GaAs-InGaAs-AlGaAs 2DEG." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/highly-sensitive-nano-tesla-quantum-well-hall-effect-integrated-circuits-using-gaasingaasalgaas-2deg(cec2fce1-7cf5-4d36-918d-873e0d38cac0).html.

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Hall Effect integrated circuits are used in a wide range of applications to measure the strength and/or direction of magnetic fields. These sensors play an increasingly significant role in the fields of automation, medical treatment and detection thanks largely to the enormous development of information technologies and electronic industries. Commercial Hall Effect ICs available in the market are all based on silicon technology. These ICs have the advantages of low cost and compatibility with CMOS technology, but suffer from poor sensitivity and detectability, high power consumption and low operating frequency bandwidths. The objective of this work was to develop and fabricate the first fully monolithic GaAs-InGaAs-AlGaAs 2-Dimensional Electron Gas (2DEG) Hall Effect integrated circuits whose performance enhances pre-existing technologies. To fulfil this objective, initially 2 µm gate length pHEMTs and 60/20 µm (L/W) Greek cross Hall Effect sensors were fabricated on optimised GaAs-In.18Ga.82As-Al.35Ga.65As 2DEG structures (XMBE303) suitable for both sensor and integrated circuit designs. The pseudomorphic high electron mobility transistors (pHEMTs) produced state-of-the-art output conductance, providing high intrinsic gain of 405, current cut-off frequency of 4.8 GHz and a low negative threshold voltage of -0.4 V which assisted in designing single supply ICs with high sensitivity and wide dynamic range. These pHEMTs were then accurately modelled for use in the design and simulation of integrated circuits. The corresponding Hall sensor showed a current sensitivity of 0.4 mV/mA.mT and a maximum magnetic DC offset of 0.35 mT at 1 V. DC digital (unipolar) and DC linear Hall Effect integrated circuits were then designed, simulated, fabricated and fully characterised. The DC linear Hall Effect IC provided an overall sensitivity of 8 mV/mT and a power consumption as low as 6.35 mW which, in comparison with commercial Si DC linear Hall ICs, is at least a factor of 2 more power efficient. The DC digital (unipolar) Hall Effect IC demonstrated a switching sensitivity of 6 mT which was at least ~50% more sensitive compared to existing commercial unipolar Si Hall ICs. In addition, a novel low-power GaAs-InGaAs-AlGaAs 2DEG AC linear Hall Effect integrated circuit with unprecedented sensitivity and wide dynamic range was designed, simulated, fabricated and characterised. This IC provided a sensitivity of 533 nV/nT, minimum field detectability of 177 nT (in a 10 Hz bandwidth) at frequencies from 500 Hz up to 200 kHz, consuming only 10.4 mW of power from a single 5 V of supply. In comparison to commercial Si linear Hall ICs, this IC provides an order of magnitude larger sensitivity, a factor of 4 higher detectability, 20 times wider bandwidth and over 20% lower power consumption (10.4 mW vs. 12.5 mW). These represent the first reported monolithic integrated circuits using a CMOS-like technology but in GaAs 2DEG technology and are extremely promising as complements, if not alternatives, to CMOS Si devices in high performance applications (such as high temperatures operations (>150 °C) and radiation hardened environment in the nuclear industry).

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Häfele, Martin. "High-speed wideband GaAs PHEMT amplifiers for 40 gb/s fiber-optic communication systems." Göttingen Cuvillier, 2009. http://d-nb.info/99641861X/04.

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Ian, Ka Wa. "Routes to cost effective realisation of high performance submicron gate InGaAs/InAlAs/InP pHEMT." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/routes-to-cost-effective-relisation-of-high-performance-submicron-gate-ingaasinalasinp-phemt(5aac071c-a4c8-48c7-aadf-e1f3e562e384).html.

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The Square Kilometre Array (SKA) is known to be the most powerful radio telescope of its type. In support of its high observational power, it is estimated that thousands of antenna unit equipped with millions of LNA (low noise amplifier) will be deployed over a large area (radius>3000km). The stringent requirements for high performance and low cost LNA design bring about many challenges in terms of material growth, device fabrication and low noise circuit designs. For the past decade, the Manchester group has been wholeheartedly committed to the research and development of high performance, low cost Monolithic Microwave Integrated Circuit (MMIC) LNA with high breakdown (15V) and low noise characteristics (1.2dB to 1.5dB) for the SKA mid-frequency application (0.4GHz to 1.4GHz). The on-going optimisation of current design is hindered by the restriction of standard i-line 1µm gate lithography. The primary focus of this work is on the design and fabrication of new, submicron gate InGaAs/InAlAs/InP pHEMTs for high frequency applications and future SKA high frequency bands. The study starts with the design and fabrication of InGaAs-InAlAs pHEMT sub-100nm gate structure using E-Beam lithography. To address the problems of short channel effect and parasitic components, devices with 128nm T-gate structure, and with optimised device geometries and enhanced material growth, having fT of 162GHz and fmax of 183GHz are demonstrated, outlining the importance of device scaling for high speed operation. In addition, a gate-sinking technique using Pd/Ti/Au metallisation scheme was investigated to meet the requirement for single voltage supply in circuit design. Device with Pd-buried gate exhibits enhanced DC and RF characteristics and showed no degradation over 5 hours’ annealing at 230˚C. The implementation of this highly thermal stable Pd Schottky gate is key to improving the device’s long-term reliability at high-temperature operation. To solve the problem of low productivity in E-Beam lithography, a simple, low cost, technique termed soft reflow was introduced by utilising the principle of solvent vaporisation in a closed chamber. It provides a hybrid solution for the fabrication of submicron device using low cost i-line lithography. The integration of this new soft reflow process with the Pd-gate sinking technique has enabled the large-scale fabrication of 250nm T-gate pHEMTs, with excellent fT of 108GHz and a fmax of 119GHz and with device yields exceeding 80%. This novel soft reflow technique provides a high yield, fast throughput, solution for the fabrication of submicron gate pHEMT and other ultra-high frequency nanoscale devices.

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Sajedin, M., Issa T. Elfergani, Jonathan Rodriguez, Raed A. Abd-Alhameed, M. Fernandez-Barciela, and M. Violas. "Ultra-Compact mm-Wave Monolithic IC Doherty Power Amplifier for Mobile Handsets." MDPI, 2021. http://hdl.handle.net/10454/18600.

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Yes
This work develops a novel dynamic load modulation Power Amplifier (PA) circuity that can provide an optimum compromise between linearity and efficiency while covering multiple cellular frequency bands. Exploiting monolithic microwave integrated circuits (MMIC) technology, a fully integrated 1W Doherty PA architecture is proposed based on 0.1 µm AlGaAs/InGaAs Depletion- Mode (D-Mode) technology provided by the WIN Semiconductors foundry. The proposed wideband DPA incorporates the harmonic tuning Class-J mode of operation, which aims to engineer the voltage waveform via second harmonic capacitive load termination. Moreover, the applied post-matching technique not only reduces the impedance transformation ratio of the conventional DPA, but also restores its proper load modulation. The simulation results indicate that the monolithic drive load modulation PA at 4 V operation voltage delivers 44% PAE at the maximum output power of 30 dBm at the 1 dB compression point, and 34% power-added efficiency (PAE) at 6 dB power back-off (PBO). A power gain flatness of around 14 ± 0.5 dB was achieved over the frequency band of 23 GHz to 27 GHz. The compact MMIC load modulation technique developed for the 5G mobile handset occupies the die area of 3.2.
This research was funded by the European Regional Development Fund (FEDER), through COMPETE 2020, POR ALGARVE 2020, Fundação para a Ciência e a Tecnologia (FCT) under i-Five Project (POCI-01-0145-FEDER-030500). This work is also part of the POSITION-II project funded by the ECSEL joint Undertaking under grant number Ecsel-345 7831132-Postitio-II-2017-IA. This work is supported by FCT/MCTES through national funds and when applicable co-funded EU funds under the project UIDB/50008/2020-UIDP/50008/2020. The authors would like to thank the WIN Semiconductors foundry for providing the MMIC GaAs pHEMT PDKs and technical support. This work is supported by the Project TEC2017-88242-C3-2-R- Spanish Ministerio de Ciencia, Innovación e Universidades and EU-FEDER funding.

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Déchansiaud, Adeline. "Conception, modélisation et caractérisation de cellules de puissance innovantes en technologie MMIC pour des applications spatiales." Limoges, 2012. https://aurore.unilim.fr/theses/nxfile/default/4b52fe2b-3c3b-4b52-98c8-3ee51417530c/blobholder:0/2012LIMO4056.pdf.

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Ce document montre comment améliorer la compacité des amplificateurs de puissance en bande Ku utilisés dans les systémes VSAT en proposant une nouvelle topologie de cellule de puissance élémentaire appelée ≪ cascode intégré ≫. La cellule active est constituée de deux transistors MMIC fabriqués avec la technologie PHEMT GaAs de la filiére UMS PPH25X. Les sources du premier transistor possédent des vias holes qui assurent un gain élevé et une bonne stabilité thermique. De plus, ils permettent une approche distribuée pour la modélisation de la cellule (intégration de composants entre les doigts de grilles) et imposent une parfaite symétrie à la structure. Le nombre de cellules élémentaires peut être ajusté afin de pouvoir délivrer la puissance totale désirée. Le facteur de forme du cascode intégré est de 1 alors que le facteur de forme du transistor correspondant (même développement de grille) est de 4. Cette cellule a été caractérisée et son modèle validé. Elle a permis la conception d’un amplificateur MMIC d´elivrant 2W en bande Ku avec des performances proche de l’état de l’art. Une réduction de la surface totale de l’amplificateur d’environ 40 % a été atteinte
This report deals with the reduction of Ku-band power amplifiers area used in VSAT equipments. Therefore, a new unitary power cell called ≪ Integrated cascode ≫ has been designed. This new cell is composed of two MMIC GaAs transistors of the UMS PPH25X foundry. The sources of the first transistor exhibit via holes. These via holes ensure a high gain and a good thermal stability. Moreover, a distributed approach can be adopted (components integration between gate fingers). They also allow a perfect symmetry of the structure. The number of unitary cell can be adjusted in order to deliver the global power expected. The shape factor of the integrated cascode is equal to 1 whereas the shape factor of a single transistor with the same gate development is equal to 4. This cell has been measured and its model has been validated. The integrated cascode has been used to design a 2W MMIC Ku-band amplifier. The amplifier area is decreased of 40 %

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20

Shinghal, Priya. "Ultra-broadband GaAs pHEMT MMIC cascode Travelling Wave Amplifier (TWA) design for next generation instrumentation." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/ultrabroadband-gaas-phemt-mmic-cascode-travelling-wave-amplifier-twa-design-for-next-generation-instrumentation(37fc42a1-d865-4ee9-bd19-35b5699249b2).html.

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Ultra-broadband Monolithic Microwave Integrated Circuit (MMIC) amplifiers find applications in multi-gigabit communication systems for 5G and millimeter wave measurement instrumentation systems. The aim of the research was to achieve maximum bandwidth of operation of the amplifier from the foundry process used and high reverse isolation ( < -25.0 dB) across the whole bandwidth. To achieve this, several design variations of DC - 110 GHzMMIC Cascode TravellingWave Amplifier (TWA) on 100 nm AlGaAs/GaAs pHEMT process were done for application in next generation instrumentation and high data transfer rate (100 Gb/s) optical modulator systems. The foundry service and device models used for the design are of the WINPP10-10 process from WIN Semiconductor Corp., Taiwan, a commercial and highly stable process. The cut-off frequency ft and maximum frequency of oscillation fmax for this process are 135 GHz and 185 GHz respectively. Thus, the design was aimed at pushing the ultimate limits of operation for this process. The design specifications were targeted to have S21 = 9.0 to 10.0 ± 1.0 dB, S11 & S22 ≤ -10.0 dB and S12 ≤ -25.0 dB in the whole frequency range. In order to achieve the targeted RF performance, it is imperative to have accurate transistor models over the frequency range of operation, transistor configuration mode and operating bias points. Using smaller periphery transistors results in lower extrinsic & intrinsic input and output capacitances that lead to achieving very wide band performance. Thus, device sizes as small as 2x10 μm were used for the design. A cascode topology, which is a series connection of a common-source and common-gate field effect transistor (FET), was used to achieve large bandwidth of operation, high reverse isolation and high input and output impedance. Using very small periphery devices at cascode bias points posed limitation in the design in terms of accuracy of transistor models under these conditions, specifically at high frequencies i.e., above 50 GHz. One of the major systemrequirements for the application of MMIC ultra-broadband amplifiers in instrumentation is to achieve and maintain high reverse isolation (≤ -25.0 dB) over the whole frequency range of operation which cannot be achieved alone by the cascode topology and new design techniques have to be devised. These twomajor challenges, namely high frequency small periphery FET model modification & development and design technique to achieve high reverse isolation in ultra-broadband frequency range have been addressed in this research.

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21

Webber, Scott. "Design of Ultra Wideband Low Noise Amplifier for Satellite Communications." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1703346/.

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This thesis offers the design and improvement of a 2 GHz to 20 GHz low noise amplifier (LNA) utilizing pHEMT technology. The pHEMT technology allows the LNA to generate a boosted signal at a lower noise figure (NF) while consuming less power and achieving smooth overall gain. The design achieves an overall gain (S21) of ≥ 10 dB with an NF ≤ 2 dB while consuming ≤ 30 mA of power while using commercial off-the-shelf (COTS) components.

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22

Mirous, Brian K. "SYNTHESIS AND PRESUMPTIVE CROSSLINKING OF STIMULI-RESPONSIVE DIBLOCK POLYMER BRUSHES." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1144783034.

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23

Asad, Bashar Z. J. "Low-Noise 24 GHz 0.15μm GaAs pHEMT Gilbert Cell Mixer for Intelligent Transportation System Radar Receiver." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31547.

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Road traffic accidents are considered as the third cause of human deaths worldwide, while leaving many others with severe injuries and/or in psychological and economical fragile situations. Therefore, several research works have been achieved to improve the reliability of transportation systems. During the last few years, intelligent transportation systems (ITS) have been developed, focusing on traffic-safety and traffic-assist systems, to name a few. One of the most common ITS, that integrate between communications and information technology, is the radar sensor working at 24 GHz. In this work, the first mixer stage of a modified ITS radar receiver was designed with an output intermediate frequency of 5.2 GHz, i.e., covering frequency bands accessible to emergency or police services, two of the front-line services involved in road accidents. The designed Gilbert cell mixer uses the 0.15 μm PHEMT GaAs technology. With a conversion gain of 8.7 dB, a single sideband noise figure of 7 dB, a linearity of -13.5 dBm as well as an isolation more than 30 dB, this mixer largely meets the Radar specifications.

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24

Steighner, Jason. "Investigation and trade study on hot carrier reliability of the PHEMT for DC and RF performance." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5048.

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A unified study on the hot carrier reliability of the Pseudomorphic High Electron Mobility Transistor (PHEMT) is carried out through Sentaurus Device Simulation, measurement, and physical analyses. A trade study of devices with four various geometries are evaluated for DC and RF performance. The trade-off of DC I-V characteristics, transconductance, and RF parameters versus hot carrier induced gate current is assessed for each device. Ambient temperature variation is also evaluated to observe its impact on hot carrier effects. A commercial grade PHEMT is then evaluated and measured to demonstrate the performance degradation that occurs after a period of operation in an accelerated stress regime--one hour of high drain voltage, low drain current stress. This stress regime and normal operation regime are then modeled through Sentaurus. Output characteristics are shown along with stress mechanisms within the device. Lastly, a means of simulating a PHEMT post-stress is introduced. The approach taken accounts for the activation of dopants near the channel. Post-stress simulation results of DC and RF performance are then investigated.
ID: 030423238; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2011.; Includes bibliographical references (p. 46-47).
M.S.
Masters
Electrical Engineering and Computer Science
Engineering and Computer Science

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Lima, Lonetá Lauro 1982. "Contribuição à fabricação e caracterização de hidrogéis de pHEMA com objetivo de produção de cartilagem artificial." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263527.

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Orientadores: Cecília Amélia de Carvalho Zavaglia, Vanessa Petrilli Bavaresco
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-23T08:52:06Z (GMT). No. of bitstreams: 1 Lima_LonetaLauro_D.pdf: 3772105 bytes, checksum: ad6e43883313d496e11ffb1ce6a798d9 (MD5) Previous issue date: 2013
Resumo: A área de biomateriais tem crescido e desenvolvido tecnologias para acompanhar e suprir as demandas que tem surgido a cada dia na área médica. Os novos biomateriais são produtos versáteis que atuam, combatem ou reparam inúmeras limitações e patologias. Dentro da classe de biomateriais poliméricos os hidrogéis têm sido cada vez mais estudados devido as suas características serem adequadas para várias aplicações biomédicas, dentre elas a cartilagem articular. As tecnologias de fabricação também tem acompanhado o desenvolvimento dos biomateriais. A prototipagem rápida tem impulsionado as pesquisas na área biomédica e permitido a biofabricação de estruturas complexas que existe no corpo humano e de animais. A biofabricação integra os fundamentos da engenharia e o conhecimento da área biomédica para produzir dispositivos biocompatíveis que possam ser utilizados na área biomédica. Esse trabalho é um estudo para verificar a viabilidade de fabricar substratos de poli (metacrilato de 2-hidroxietila) (pHema) usando um equipamento desenvolvido pelo grupo de pesquisadores do INCT Biofabris da Unicamp. Esse equipamento de biofabricação utiliza os princípios da estereolitografia por irradiação direta com luz UV-Visível para fabricar dispositivos médicos Os substratos foram produzidos utilizando seis diferentes composições químicas, para verificar a influência da composição química nas propriedades mecânicas, biológicas e biotribológicas dos hidrogéis. Foi verificado que os substratos produzidos com maior densidade de reticulação promove maior proliferação celular
Abstract: The development of biomaterials area has grown and has developed technologies aimed to satisfy the demands that emerge every day in the medical field. New biomaterials are versatile products that act and repair numerous limitations and diseases. Within the class of polymeric biomaterials, hydrogels have been increasingly studied due to their characteristics that are suitable for various biomedical applications, such as articular cartilage. Manufacturing technologies have also followed the development of biomaterials. Rapid prototyping has driven research in the biomedical field and has allowed the biomanufacturing of complex structures that exist in the human and animals' body. The biomanufacturing integrates the fundamentals of engineering and biomedical knowledge to produce biocompatible devices that can be used in the biomedical field. This work is a study to verify the feasibility for fabrication of substrates of poly (2-hydroxyethyl methacrylate) (pHema) using an equipment developed by the research group of INCT Biofabris Unicamp. This equipment is based on the principle of stereolithography by direct irradiation with UV- visible light to fabricate medical devices. The substrates were produced using six different chemical compositions in order to verify the influence of the chemical composition on the mechanical properties, biological and biotribological properties of hydrogels. It was found that the substrate produced with higher crosslinking density promotes greater cell proliferation
Doutorado
Materiais e Processos de Fabricação
Doutora em Engenharia Mecânica

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Taggueb, Hassiba. "Conception d'amplificateurs transimpédance pour la photoreception dans des liaisons optiques à haut débit." Paris 6, 2007. http://www.theses.fr/2007PA066377.

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Les interfaces optoélectroniques sont au cœur des télécommunications par fibre optique. L'étude présentée dans ce mémoire concerne la tête de photoréception composée d'un photodétecteur associé à un préamplificateur. Ce préamplificateur est l'un des composants les plus critiques dans la chaîne de photoréception, car il détermine en particulier la sensibilité du système. Après avoir dressé un état de l'art des circuits d'extrémité, notre choix s'est porté sur un amplificateur de type transimpédance (TIA) à contre-réaction. Plusieurs architectures d’amplificateurs transimpédance ont été optimisées et réalisées avec deux technologies différentes de circuits MMIC sur GaAs (OMMIC et Win Semiconductor). Les principales contraintes fixées par les applications envisagées sont la compacité du circuit, la bande passante (supérieure à 12 GHz), le gain transimpédance (supérieur à 47 dB), la dynamique et la faible consommation. Les circuits ainsi réalisés nous permettent de disposer sur une même puce de dimension de 1 x 1. 5 mm2 deux structures TIA identiques. La comparaison des performances de ces divers circuits associée à des rétro-simulations ont mis en évidence l'importance de disposer de modèles précis de composants actifs surtout vers les hautes fréquences. Des solutions ont été proposées pour améliorer les performances du photorécepteur faisant appel à l’un de ces TIA associé à une photodiode du commerce, en particulier en ce qui concerne la bande passante
Optoelectronic interfaces are the heart of optical fiber communication systems. This work describes the optimisation of photoreception front end circuit associating a photodetector with a preamplifier. This preamplifier is one of the most critical components in the photoreception system, because it determines mainly its sensitivity. Considering the state of art of the front-end circuits, our choice was made on transimpédance amplifier (TIA) with negative feedback. Several transimpedance amplifier (TIA) architectures were optimised and realised with two different GaAs MMIC technologies (OMMIC and Win Semiconductor). The principal constraints fixed by the considered applications are circuit compactness, bandwidth (more than 12 GHz), transimpedance gain (more than 47 dB), dynamic range and low consumption. Two identical TIA structures have been implemented on the same chip with dimension of 1 x 1. 5 mm2. The performances comparison of these various circuits, associated with retro-simulations, highlighted the need of having accurate active components models, mainly at high frequencies. Solutions are also proposed to improve the photoreceiver performances, associating one of these TIAs with a photodiode, specifically for bandwidth broadening

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Wang, Zhengmu. "Design, fabrication and characterization of a double-network alginate-pHEMA hydrogel coating for PDMS-based biomedical implants." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61102.

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Traditional silicone biomedical implants, such as urinary catheters, often suffer from high surface friction, high stiffness, and a lack of hydrophilicity, which can cause discomfort or discomfort. To tackle these challenges, we developed a double-network alginate-pHEMA hydrogel “cushion” coating for polydimethylsiloxane (PDMS) biomedical implants. The double-network hydrogel presented here consists of two distinct networks made of alginate and pHEMA, respectively. The alginate network is covalently bonded to PDMS substrates as scaffolding, and the denser pHEMA network fills the free space within the alginate network. In this proof of concept study, the double-network hydrogel achieved a compressive fracture stress of 502.04±14.41 kPa, which is 5.8-fold stronger than the alginate hydrogel, while its elasticity is still comparable to soft tissues. The proposed double-network hydrogel has a negligible amount of swelling in biological fluids and exhibits no cytotoxicity, which are desirable qualities for biomedical and coating applications. Both chemical modification using APTES and micropillar anchors have been used to improve the coating stability. We found that the adhesion strength of the hydrogel coating on micropillar PDMS substrates is 55% stronger than on bare PDMS substrates when both substrates are grafted with APTES. In comparison to native PDMS and K-Y Jelly-lubricated PDMS, the double-network alginate-pHEMA hydrogel-coated PDMS demonstrated significantly less friction and superior hydrophilicity.
Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate

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Mays, Kenneth W. "A 40 GHz Power Amplifier Using a Low Cost High Volume 0.15 um Optical Lithography pHEMT Process." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/552.

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The demand for higher frequency applications is largely driven by bandwidth. The evolution of circuits in the microwave and millimeter frequency ranges always demands higher performance and lower cost as the technology and specification requirements evolve. Thus the development of new processes addressing higher frequencies and bandwidth requirements is essential to the growth of any semiconductor company participating in these markets. There exist processes which can perform in the higher frequency design space from a technical perspective. However, a cost effective solution must complement the technical merits for deployment. Thus a new 0.15 um optical lithography pHEMT process was developed at TriQuint Semiconductor to address this market segment. A 40 GHz power amplifier has been designed to quantify and showcase the capabilities of this new process by leveraging the existing processing knowledge and the implementation of high frequency scalable models. The three stage power amplifier was designed using the TOM4 scalable depletion mode FET model. The TriQuint TQP15 Design Kit also implements microstrip transmission line models that can be used for evaluating the interconnect lines and matching networks. The process also features substrate vias and the thin film resistor and MIM capacitor models which utilize the capabilities of the BCB process flow. During the design stage we extensively used Agilent ADS program for circuit and EM simulation in order to optimize the final design. Special attention was paid to proper sizing of devices, developing matching circuits, optimizing transmission lines and power combining. The final design exhibits good performance in the 40 GHz range using the new TQP15 process. The measured results show a gain of greater than 13 dB under 3 volt drain voltage and a linear output power of greater than 28 dBm at 40 GHz. The 40 GHz power amplifier demonstrates that the new process has successfully leveraged an existing manufacturing infrastructure and has achieved repeatability, high volume manufacturing, and low cost in the millimeter frequency range.

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Ahdjoudj, Mourad. "Conception de vco a faible bruit de phase en technologie monolithique phemt dans les bandes k et ka." Paris 6, 1997. http://www.theses.fr/1997PA066595.

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Ce travail est une contribution a la conception d'oscillateurs accordables a faible bruit de phase, utilisant la technologie monolithique a base de transistors phemt en bande millimetrique. Les systemes de communications actuels exigent la conception d'oscillateurs agiles en frequences et de grande purete spectrale. Ces specifications conduisent a l'adoption de methodologies de conceptions appropriees mettant en uvre les potentialites des simulateurs commerciaux. Ce memoire presente la conception d'un oscillateur controle en tension avec buffer en bande ka (autour de 30ghz). Son bruit de conversion am-fm est optimise par le critere d'orthogonalite. La conception d'un second vco sans buffer en bande k (autour de 24ghz) est basee sur l'optimisation du comportement dynamique du transistor ; l'objectif etant de reduire le bruit de phase genere par les non-linearites. La caracterisation des circuits concus et realises est effectuee. La comparaison entre les resultats obtenus par simulation et les resultats experimentaux montre un accord satisfaisant. La deuxieme partie de ce travail porte sur la modelisation du bruit basses frequences des transistors phemt ainsi que sur l'analyse du bruit de phase des vco. La caracterisation du bruit basses frequences nous a permis d'identifier les differentes composantes du bruit en exces. Un modele de bruit pour la cao des transistors phemt en fonction du courant de drain est propose. Ceci nous a permis de simuler le bruit de phase des vco. L'analyse des resultats de simulation, nous a conduit a constater l'influence du varactor sur le bruit de phase du fait de son coefficient de qualite et de ses non-linearites. Des interpretations expliquant les ecarts entre simulations-mesures sont donnees. Les niveaux du bruit de phase mesures correspondent aux meilleurs resultats releves dans la litterature a ce jour.

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Mohamad, Isa Muammar Bin. "Low Noise Amplifiers using highly strained InGaAs/InAlAs/InP pHEMT for implementation in the Square Kilometre Array (SKA)." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/low-noise-amplifiers-using-highly-strained-ingaasinalasinp-phemt-for-implementation-in-the-square-kilometre-array-ska(31b6cbae-7b7e-43fe-a612-b3555dd2263d).html.

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The Square Kilometre Array (SKA) is a multibillion and a multinational science project to build the world’s largest and most sensitive radio telescope. For a very large field of view, the combined collecting area would be one square kilometre (or 1, 000, 000 square metre) and spread over more than 3,000 km wide which will require a massive count of antennas (thousands). Each of the antennas contains hundreds of low noise amplifier (LNA) circuits. The antenna arrays are divided into low, medium and high operational frequencies and located at different positions to boost up the telescope’s scanning sensitivity.The objective of this work was to develop and fabricate fully on-chip LNA circuits to meet the stringent requirements for the mid-frequency array from 0.4 GHz to 1.4 GHz of the SKA radio astronomy telescope using Monolithic Microwave Integrated Circuit technology (MMIC). Due to the number of LNA reaching figures of millions, the fabricated circuits were designed with the consideration for low cost fabrication and high reliability in the receiver chain. Therefore, a relaxed optical lithography with Lg = 1 µm was adopted for a high yield fabrication process.Towards the fulfilment of the device’s low noise characteristics, a large number of device designs, fabrication and characterisation of InGaAs/InAlAs/InP pHEMTs were undertaken. These include optimisations at each critical fabrication steps. The device’s high breakdown and very low gate leakage characteristics were further improved by a combination of judicious epitaxial growth and manipulation of materials’ energy gaps. An attempt to increase the device breakdown voltage was also employed by incorporating Field Plate structure at the gate terminal. This yielded the devices with improvements in the breakdown voltage up to 15 V and very low gate leakage of 1 µA/mm, in addition to high transconductance (gm) characteristic. Fully integrated double stage LNA had measured NF varying from 1.2 dB to 1.6 dB from 0.4 GHz to 1.4 GHz, compared with a slightly lower NF obtained from simulation (0.8 dB to 1.1 dB) across the same frequency band.These are amongst the attractive device properties for the implementation of a fully on-chip MMIC LNA circuits demonstrated in this work. The lower circuit’s low noise characteristic has been demonstrated using large gate width geometry pHEMTs, where the system’s noise resistance (Rn) has successfully reduced to a few ohms. The work reported here should facilitate the successful implementation of rugged low noise amplifiers as required by SKA receivers.

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Jacob, Kane, and Bala Bhaskar Gudey. "Co-Design of Antenna and LNA for 1.7 - 2.7 GHz." Thesis, Linköpings universitet, Fysik och elektroteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-85953.

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In a radio frequency (RF) system, the front-end of a radio receiver consists of an active antenna arrangement with a conducting mode antenna along with an active circuit. This arrangement helps avoid losses and SNR degradation due to the use of a coaxial cable. The active circuit is essentially an impedance matching network and a low noise amplification (LNA) stage. The input impedance of the antenna is always different from the source impedance required to be presented at the LNA input for maximum power gain and this gives rise to undesired reflections at the antenna-LNA junction. This necessitates a matching network that provides the impedance matching between the antenna and the LNA at a central frequency (CF). From the Friis formula it is seen that the total noise figure (NF) of the system is dependent on the noise figure and gain of the first stage. So, by having an LNA that provides a high gain (typically >15 dB) which inserts minimum possible noise (desirably < 1 dB), the overall noise figure of the system can be maintained low. The LNA amplifies the signal to a suitable power level that will enable the subsequent demodulation and decoding stages to efficiently recover the original signal. The antenna and the LNA can be matched with each other in two possible ways. The first approach is the traditional method followed in RF engineering where in both the antenna and LNA are matched to 50 W terminations and connected to each other. In this classical method, the antenna and LNA are matched to 50 W at the CF and does not take into account the matching at other frequencies in the operation range. The second approach employs a co-design method to match the antenna and LNA without a matching network or with minimum possible components for matching. This is accomplished by varying one or more parameters of either the antenna or LNA to control the impedances and ultimately achieve a matching over a substantial range of frequencies instead at the CF alone. The co-design method is shown to provide higher gain and a lower NF with reduced number of components, cost and size as compared to the classical method. The thesis work presented here is a study, design and manufacturing of an antenna-LNA module for a wide frequency range of 1.7 GHz – 2.7 GHz to explore the gain and NF improvements in the co-design approach. Planar micro strip patch antennas and GaAs E-pHEMT transistor based LNA’s are designed and the matching and co-design are simulated to test the gain and NF improvements. Furthermore, fully functional prototypes are developed with Roger R04360 substrate and the results from simulations and actual measurements are compared and discussed.

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Monção, Ana Paula dos. "Sintese de hidrogeis de phema para liberação controlada de drogas e meios acido e neutro e estudo da difusão." [s.n.], 1997. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267384.

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Orientadores: Sergio Persio Ravagnani, Lucia H. I. Mei
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
Made available in DSpace on 2018-07-23T10:54:20Z (GMT). No. of bitstreams: 1 Moncao_AnaPaulados_M.pdf: 2013063 bytes, checksum: c53abd549d973c08134f44a47800b23e (MD5) Previous issue date: 1997
Resumo: Neste trabalho, hidrogéis de poli(2-hidroxietil metacrilato) ¿ PHEMA foram preparados por reticulação química, usando N,N¿ metileno ¿ bis ¿ acrilamida como agente reticulante. Hidrogéis de diferentes graus de reticulação foram obtidos variando-se a concentração do reticulante de 0,12% a 3% (p/p). Os filmes de PHEMA obtidos foram caracterizados através de análise de calorimetria diferencial de varredura ¿ DSC, microscopia eletrônica de varredura ¿ MEV e ensaio de tração. Dentre essas análises, o ensaio de tração foi o que mais mostrou as alterações das propriedades dos hidrogéis obtidos. O intumescimento foi estimado a partir da variação ocorrida no peso das amostras quando atingiram o equilíbrio, imersas em água destilada e solução tampão a pH=1, à temperatura ambiente. Observou-se que há influencia do meio externo no intumescimento do hidrogel. Os estudos da difusão foram realizados utilizando-se Rodamina B como espécie difusiva. As análises de difusão foram realizadas a ¿37 GRAUS¿C, em solução tampão de pH=1 e água destilada, pH~7. o coeficiente de difusão do soluto (D) foi calculado através da '2 POT. a¿ lei de Fick. Os dados experimentais obtidos e a elaboração de um modelo matemático permitiram a avaliação do coeficiente de difusão, utilizando-se métodos numéricos iterativos, os resultados obtidos mostraram que há reticulação física na formação do hidrogel de PHEMA, permitindo a sua utilização sem agente reticulante. Com a adição do agente reticulante, observou-se uma significativa alteração do coeficiente de difusão
Abstract: In this work, hydrogels of poly (2 ¿ hydroxyethyl methacrylate) ¿ PHEMA were prepared by chemical crosslinks using N, N¿methylene ¿ bis ¿ acrylamide as the crosslinking agent. Hydrogels with different crosslinking degrees were obtained by varying the crosslinker concentration from 0.12% up to 3.0% (w/w). the films of PHEMA obtained were characterized by differential scanning calorimetry ¿ DSC, scanning electron microscopy ¿ MEV and mechanical properties. The mechanical tensile test was the method of characterization that showed more properties variation of the hydrogels obtained. The swelling was estimated by the variation in the samples weight when they reached the equilibrium, after have been immersed into distilled water and buffer solution at room temperature. It was observed that there is influence of the pH in the hydrogel swelling. The diffusion studies were carried out using Rhodamine B as the diffusive model specimen. The diffusion analysis were conducted at ¿37 GRAUS¿C, in buffer solution at pH=1 and distilled water at pH~7. The Fick¿s Second Law has been used to calculate the solute diffusion coefficient (D). The experimental data obtained and the mathematical model elaborated permited the evaluation of diffusion coefficient using iterative numerical methods. The results obtained have shown that there is physical crosslinking in the PHEMA hydrogel formation, so its utilization without crosslinker was permited. A significative variation of the diffusion coefficient was observed when the crosslinking agent was added.
Mestrado
Ciencia e Tecnologia de Materiais
Mestre em Engenharia Química

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Vildeuil, Jean-Charles. "Caractérisation et modélisation basse fréquence de transistors PHEMT AlGaAs/InGaAS/GaAs : bruits du canal, de la grille et corrélation." Montpellier 2, 2000. http://www.theses.fr/2000MON20151.

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La realisation d'un oscillateur a haute purete spectrale passe obligatoirement par une phase de conception assistee par ordinateur afin de determiner la topologie optimale du circuit oscillateur en terme de bruit de phase. Le bruit de phase de l'oscillateur etant etroitement lie au bruit basse frequence du transistor utilise, ici des phemts (pseudomorphic high electron mobility transistors), il faut etudier le comportement en bruit de fond du composant. L'objet de ce travail est donc sur le plan pratique l'elaboration de schemas equivalents rendant compte du fonctionnement statique ou dynamique du transistor et prenant en compte les differentes sources de bruit basse frequence presentes dans le composant. Ces modeles seront ensuite utilises pour la simulation precise des oscillateurs concus. Apres une breve description des caracteristiques des oscillateurs, nous presentons dans ce memoire le principe de fonctionnement des transistors hemt et les phenomenes mis en jeu pour aboutir aux equations de conduction. A partir de ces equations, une methodologie de caracterisation a permis d'extraire l'ensemble des parametres electriques rendant compte de maniere satisfaisante du fonctionnement du composant. Les mesures experimentales relatives aux bruits de fond du drain et de l'electrode de commande ont egalement ete analysees dans le detail. Enfin, la fonction de coherence entre le bruit associe a la grille et celui associe au drain est etudiee. La simulation presentee permet de valider les schemas equivalents et les modeles proposes.

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34

Tan, Jimmy Pang Hoaw. "Thermal and small-signal characterisation of AlGaAs/InGaAs pHEMTs in 3D multilayer CPW MMIC." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/thermal-and-smallsignal-characterisation-of-algaasingaas-phemts-in-3d-multilayer-cpw-mmic(4a663463-af52-4a35-a570-01ca41e2baa0).html.

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Rapid advancement in wireless communications over the years has been the driving force for many novel technologies providing compact and low cost solutions. Recent development of multilayer coplanar waveguide (CPW) MMIC technology promises realization of 3D MMIC in which large area-occupying passive components are translated from horizontal into vertical configuration resulting compact structure. The other main advantages of this technology are elimination of via-holes and wafer-thinning giving alternative performance solution, if not better, from the traditional MMIC. In this thesis, thermal and small-signal characteristics of prefabricated AlGaAs/InGaAs pseudomorphic high electron mobility transistors (pHEMTs) on semi-insulating (S.I.) GaAs substrate incorporated in the 3D MMIC technology have been analysed and modelled for the first time. A comprehensive small-signal parameter extraction procedure has been successfully developed which automatically determines the device small-signal parameters directly from the measured S-parameters. The developed procedure is unique since it provides a great deal of data on measured devices over a wide bias, temperature and frequency range for future incorporation of different active devices for the 3D MMIC technology and provides a first hand knowledge of how the multilayer structure will affect the performance of pre-fabricated pHEMTs. The extracted small-signal models of both pre- and post- multilayer processed pHEMTs have been compared and validated to the RF S-parameters measurements. The main focus was drawn upon the temperature dependent model parameters and how the underlying physics of the transistors behave in response to the change of temperature. These novel insights are especially valuable for devices designed specifically for high power applications like power amplifiers where tremendous heat could be generated. The data can also be interpreted as a way to optimise the multilayer structure, for example, alternative material with different properties can be implemented. The governing physics affecting device performance are also modelled and discussed empirically in details through extracted device parameters. These investigations would assist in the development of reliable, efficient and low cost production of future compact 3D multilayer CPW MMICs.

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Amsaaed, Salem. "Copper Grafted Titanium Dioxide in Hydrogels for Photocatalysts." DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 2018. http://digitalcommons.auctr.edu/cauetds/155.

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This study are based on the premise that the incorporation of metal ions into nano titania-PHEMA [poly (2-hydroxyethyl methacrylate)] hydrogels would enhance the desirable properties in the photodecomposition of pollutants. The investigation are centered in the use of Cu(II) as metal ion of interest. The development of TiO2-PHEMA-Cu hydrogels was conducted, and the characterization of the materials by FT-IR, XRD and fluorescence was performed. The absorption of copper(II) from the solution was monitored by UV-Vis. The FT-IR are found too, be the most effective tool too, analyze the interaction of Cu(II) with PHEMA in the nanocomposite hydrogels. The free carbonyl group has the IR band at 1715 cm-1 in the TiO2-PHEMA. Upon uptaking Cu(II), the hydrogels showed a new band at 1595 cm-1. Further examination establishes the relationship between the two bands. The time-dependent study revealed that the intensity of band at 1595 cm-1 would increase while that at 1715 cm-1 would decrease as the time for uptaking Cu(II) increased. A concentration-dependent study also demonstrated the same trend that showed the intensities of the two bands moved in the opposite directions.

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SHARMA, HARSHITA. "SOFT COMPUTING FOR RUMOUR ANALYTICS ON BENCHMARK TWITTER DATA." Thesis, 2019. http://dspace.dtu.ac.in:8080/jspui/handle/repository/16701.

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As social media is a fertile ground for origin and spread of rumours, it is imperative to detect and deter rumours. Various computational models that encompass elements of learning have been studied on benchmark datasets for rumour resolution with four individual tasks, namely rumour detection, tracking, stance and veracity classification. Quick rumour detection during initial propagation phase is desirable for subsequent veracity and stance assessment. This research presents the use of adaptive and heuristic optimization to select a near-optimal set of input variables that would minimize variance and maximize generalizability of the learning model, which is highly desirable to achieve high rumour prediction accuracy. An empirical evaluation of hybrid filter-wrapper on PHEME rumour dataset is done. The features are extracted initially using the conventional term frequency-inverse document frequency (TF-IDF) statistical measure and to select an optimal feature subset two filter methods, namely, information gain and chi-square are separately combined with three swarm intelligence-based wrapper methods, cuckoo search, bat algorithm and ant colony optimization algorithm. The performance results for the combinations have been evaluated by training three classifiers (Naïve Bayes, Random Forest and J48 decision tree) and an average accuracy gain of approximately 7% is observed using hybrid filter-wrapper feature selection approaches. Chi-square filter with Cuckoo and ACO give the same maximum accuracy of 61.19% whereas Chi-square with bat gives the maximum feature reduction selecting only 17.6% iv features. The model clearly maximizes the relevance and minimizes the redundancy in feature set to build an efficient rumour detection model for social data. Due to the ever increasing use and dependence of netizens on social media, it has become a fertile ground for breeding Rumours. This work aims to propose a model for Potential Rumour Origin Detection (PROD) to enable detection of users who can be likely rumour originators. It can not only help to find the original culprit who started a rumour but can aid in veracity classification task of the rumour pipeline as well. This work uses features of the user’s account and tweet to extract meta-data. This meta-data is encoded in an 8 tuple feature vector. A credibility quotient for each user is calculated by assigning weights to each parameter. The higher the credibility of a user, less likely it is to be a rumour originator. Based on the credibility, a label is assigned to each user indicating whether it can be a potential rumour source or not. Three supervised machine learning algorithms have been used for training and evaluation and compared to a baseline zeroR classifier. The results have been evaluated on benchmark PHEME dataset and it is observed that the multi-layer perceptron classifier achieves the highest performance accuracy, that is, an average 97.26% for all five events of PHEME to detect potential rumour source.

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37

洪國瀛. "pHEMT Antenna Switch." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/18587502090994435879.

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碩士
明新科技大學
電機工程研究所
95
pHEMT antenna switch has been widely used into advanced monolithic microwave integrated circuits (MMIC) for modern microwave system applications. The advantages of the AlGaAs/InGaAs pseudomorphic high-electron-mobility transistor(pHEMT) antenna switch are low insertion loss , high isolation , and high power handling. A double pole double throw (DPDT) switch has been fabricated and tested for DC-6GHz application. The number of the gate finger is chosen as 2 , and the die area is 1278μm x 1154μm .The control voltage used for the switch is 3V. The measured insertion loss is 1.1dB at 2.45GHz. The isolation of the device is 47dB, and the power 1dB compression point (P1dB) is 30 dBm . The insertion loss is 1.1 dB , the isolation is 35dB, and P1dB is 29.5 dBm at 5.8GHz. A typical application of the DPDT switch is for diversity antenna switching in IEEE 802.11a/b/g Wireless LAN systems. In future, the 4P4T switch will be studied for MIMO application.

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Chang, Jhe-jia, and 張哲嘉. "Equivalent Circuit Model of pHEMT." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/76983379795309628889.

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碩士
國立雲林科技大學
光學電子工程研究所
95
In this thesis, device models are established for pHEMTs. The device models include a small-signal model and a large-signal model. Conventionally, Yang-Long’s measurement technique was used to extract the source parasitic resistance Rs, and then the cold-FET measurement was performed to extract other parasitic parameters of small-signal model. After extracting the parasitic parameters, one removes the parasitic effects to obtain the intrinsic equivalent circuit of pHEMTs with mathematic algorithms. Finally, using Y-parameters in the intrinsic circuit, one can calculate the intrinsic parameters. In contrast, a new technique using the influence of high-frequency parameters on high-frequency characteristics is proposed in this thesis. A specific procedure of several steps is presented to extract parameters of the small signal model systematically, and the extracted result is satisfactory. To extract DC parameters in the large signal model, equations of the EEHEMT model are used. A specific procedure of extracting DC parameters is developed without using the IC-CAP extraction software. DC characteristics are measured to extract the parameters of the large signal model. Simulation using the ADS (Advanced Design System) software is compared with measurement. The simulated result closely matches the DC measurement. The research results also provide a better insight into the EEHEMT model.

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Tu, Min-Chang, and 杜明昌. "Optimization of HBT/pHEMT integration technology." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/92327930388865958989.

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博士
國立中山大學
電機工程學系研究所
98
The InGaP Heterojunction Bipolor Transistors (HBTs) become known as the dominant technology in handset power amplifiers. Modern application requirements and size limitations have driven industry leaders towards the co-integration of enhance/depletion mode pHEMT and HBT. The combination of BiFET gives an additional degree of freedom in the design of advanced power amplifiers combine switch. This dissertation provides an overview of the various techniques. Critical processes included gate photolithography and Polyimide planarize process are discussed in detail. The 0.5-μm multiple gate fingers fabricated on the controllable small un-gated region of a high-topology wafer was overcome by using a bi-layer photolithography process. The fabricated of polyimide was used as the dielectric interlayer to reduce the interconnect crossover parasitic capacitance and planarize the second metal process for metal shunt application. The metal shunt structures provide greater functionality and design flexibility under shrinking. Finally, presents the combine the best features of InGaP HBT-pHEMT integration technology. The HBT and E/D-pHEMT electrical performances (DC, small signal, noise, and power) are presented. The results indicate that this technology offers great potential and degrees of freedom to design power amplifiers, high-integrated RF transceivers, and opportunities for the development of novel RFIC circuits.

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40

郭李瑞. "PHEMT T/R Switch for Wireless Application." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/45732409372720201572.

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碩士
明新科技大學
電機工程研究所
93
Transmit/Receive (T/R) switch has been widely used into advanced monolithic microwave integrated circuits (MMIC) for modern microwave system applications. The advantages of the AlGaAs/InGaAs pseudomorphic high-electron-mobility transistor (PHEMT) T/R switch are : low Insertion loss, high Isolation, low control voltage , small size, and high power handling. A single pole double throw (SPDT) pHEMT T/R switch has been fabricated and tested for DC-6GHz applications. The number of the gate finger is chosen as 2, and the gate width is 1650um. In this paper, The performance of the switch was compared with the different gate widths, gate number and different value of capacitors. The control voltage used for the switch is 3.0V. The measured Insertion loss is 0.36dB at 2.4GHz. The Isolation of the device is 26dB, and the power 1dB compression point is 26dBm. The Insertion loss is 1.7dB, and the Isolation is 17dB at 5.8GHz. This switch is used for the IEEE802.11a/b/g applications.

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41

Peng, AnSam, and 彭安賢. "The Analysis of HBT and PHEMT Power Devices." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/92869971566581023621.

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碩士
國立中興大學
電機工程學系
89
With the rapid developments of wireless communication , Power Amplifiers (PA) not only require high output power, power-added efficiency, but also high linearity. For the performance of power amplifiers, the most important components are the power devices we used. The most widely used power devices are PHEMT and HBT now. Therefore this thesis focuses on the characteristics of PHEMT and HBT and performs several power measurements. In addition, we analyze the gain compression mechanism and different impedance load lines. This thesis is divided into three subjects. The first subject is the basic concepts of power measurement and load impedance. In the second subject we analyze the gain compression of PHEMT, such as knee voltage, pinch-off voltage, breakdown voltage, the maximum drain current and other characteristics. In the last subject we study the most important power device, HBT. HBT have very different bias operation and gain compression mechanism from PHEMT, such as Class-A operation, knee voltage, beakdown voltage, constant base voltage. In this thesis, we carefully analyze the power characteristics of these power devices in detailed and develop a new peculiar way to characterize the different gain compression mechanism. The influence of power in different load lines is also studied.

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Bai, Jing-Shian, and 白景賢. "Research of V-band pHEMT Cascode Power Amplifiers." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/18292076476272349460.

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碩士
國立臺灣大學
電信工程學研究所
99
In this thesis, three high frequency amplifiers are designed and investigated, including a V-band buffer amplifier, a V-band power amplifier and a 67-GHz power amplifier. These three circuits are implemented using pseudomorphic high electron mobility transistor (pHEMT) technology. The first part of this thesis describes the design of a buffer amplifier for V-band applications using 0.15-um low-noise pHEMT technology. The circuit consists of two stages cascode amplifier and designed using coplanar waveguide (CPW) structure to reduce the parasitic effect. The measured small signal gain is about 18 dB, and the measured saturation output power is about 3.5 dBm at 60 GHz. A power amplifier with high output power in 0.15-um power pHEMT technology is presented next. This circuit is also a two-stage design adopting cacode configuration as the driver stage and common-source configuration as the power stage. The measured saturation output power is about 22 dBm at 60 GHz. Finally, a 67-GHz power amplifier using 0.15-um low-noise pHEMT technology is presented. This circuit is realized with two-stage cascode configuration to achieve high gain and high output power. The consideration of power budget and balanced structure using Lange coupler are discussed in this chapter. There are discrepancies between simulation results and measurement results, and the reason will be discussed also. Because of the inaccuracy of the transistor model at higher frequency, the simulation results of the circuit do not agree with the measurement results. The linear model parameters are re-generated with the measured device data provided by the foundry WIN Semiconductors. Based on the new linear model parameters and the dc-IV curves, the Angelov model is established. With the new nonlinear model, the simulation results and measurement results of the circuits show better agreement.

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Chiou, Zeng-Gang, and 邱振剛. "pHEMT RFIC Design of Wideband Low Noise Amplifier." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/qud9ky.

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碩士
國立虎尾科技大學
光電與材料科技研究所
99
This thesis presents the design of ultra-wideband low noise amplifier (LNA) using WIN 0.15μm pHEMT process to design the circuit. Three frequency bands in the range of 3 GHz to 24 GHz were conducted. The LNAs adopted three kinds of configuration in this thesis. They are resistance feedback amplifier, source inductor degeneration and current reused technique. At first, a 3-10GHz low noise amplifier was designed. The adopted structure is the resistance feedback amplifier, which provides a flat gain, a good input impedance match and better stability condition for the amplifier circuit. This low noise amplifier achieves the following characteristics: gain 19.5dB~22.3dB, noise figure 6.7dB~7.7dB, input return loss -12.9dB~-14.3dB, output return loss -10.1dB~-22.5dB, and isolation -36.9dB~-39.8dB. In the second part, a Ku-band low noise amplifier was designed for the very small aperture terminal. The circuit structure is the source inductor degeneration, which provides a good input impedance match, high power transmission and low noise. This low noise amplifier achieves the following characteristics: gain 11.67dB~17.94dB, noise figure 1.454dB~2.479dB, input return loss -29.39dB~-35.44dB, output return loss -12.86dB~-20.73dB, and isolation -20.44dB~-27.99dB. Finally, a 24 GHz low noise amplifier is designed for a vehicular radar system. The structure of current reused technique was chosen which gives a high gain and low supply voltage and power consumption. Simulated data show that this low noise amplifier has a gain of 8.94dB, noise figure 2.308dB, input return loss -11.67dB, output return loss -10.93dB, and isolation -23.11dB.

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Chang, Hao-Yu, and 張皓宇. "Research on room temperature terahertz emission by 0.15μm pHEMT." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/68010667024488261389.

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碩士
國立交通大學
電子研究所
99
We demonstrate room-temperature terahertz emitters using 0.15 μm pHEMTs. The devices were fabricated by WIN semiconductors and were obtained through CIC. We measured emission intensities of the devices at different bias points. We also measured polarization of emission signals and emission spectra. We calibrated the emission spectra by using a black body source. We found that there are two emission peaks appearing at 10 THz and 15 THz. The total radiation power was calculated through the calibrated spectrum. The power level was estimated to be nearly one micro-watt. We propose an inter-subband transition model to explain the experimental data.

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45

Huang, Guan-Kai, and 黃冠凱. "AlGaAs/InGaAs/GaAs pHEMT Model Parameter Extraction and Establishment." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/21995175268224445734.

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碩士
國立成功大學
微電子工程研究所碩博士班
94
This thesis is to build the device models for AlGaAs/InGaAs/GaAs pHEMT. The device models include small-signal model, large-signal model, and RF noise model. In the beginning, we use the Yang-Long measurement to extract the parasitic resistance, Rs, and the cold-FET measurement to extract the other parasitic parameters of small-signal model. After extracting parasitic parameters, we de-embed those parasitic parameters to get the intrinsic circuit of pHEMT. Finally, with the Y-parameters and mathematics, we can calculate the intrinsic parameters. In the cold-FET measurements, we apply two different gate voltages to simplify the circuit. One is strong forward gate bias and the other is zero gate bias. We find that the parameters extracted from the zero gate bias are more accurate than those extracted from the forward gate bias. We adopt EEHEMT model for large-signal model in this thesis. With DC measurements and small-signal parameters, the EEHEMT model parameters can be obtained by fitting. Finally, we use ADS simulation software to verify the extracted results. As for noise model, we add two noise temperatures to the intrinsic circuit of small-signal model. The noise temperature model allows prediction of noise parameters for pHEMT devices.

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46

Li, Wei-Nung, and 李威儂. "The Characteristic Analysis of RF Switches for GaAs pHEMT." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/57515571045022889885.

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碩士
義守大學
電機工程學系碩士班
99
Due to the superior characteristics of low insertion loss, high isolation and high speed, GaAs pHEMT has been widely used to design RF switch. In this thesis, an RF switch for Quad-band cell phone was designed and fabricated. Since the switch is used for commercial system, the chip size and cost are main concerns. A three gates structure was employed to overcome the high power specification and the uneven structure of transmission path (two-section) and receiving path (one-section) was introduced to reduce the chip size. The simulation and measurement results were compared and showed a good agreement.

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47

Chien, Jia-Fan, and 簡佳帆. "Investigation of THz radiation from pHEMT at room temperature." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/25711043394064611851.

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碩士
國立交通大學
電子研究所
100
This thesis studies radiation characteristics of InGaAs/GaAs pHEMTs in THz region. We construct a system capable of measuring both angle-resolved intensity and radiation spectrum of a pHEMT under electrical excitations. Experimental results show that the intensity of a pHEMT has an angular distribution similar to cosθ. Furthermore, the in-tensity increases substantially when a pHEMT is biased from the linear region into the saturation region. The spectrum extends widely in fre-quencies from one to 18 THz and shows several peaks. We find that two of the peaks, at f = 9 and 15.5 THz, have an intensity ratio that depends on the angle and the input power, indicating the difference in their origin. By comparing the radiation spectrum with the absorption spectrum of a GaAs substrate, we infer that the peaks originate from thermal radiation of phonons. The peak at 9 THz comes from the radiation of optical pho-nons in GaAs while the peak at 15.5 THz from a combination of two phonons that are infrared active. The mechanism is further confirmed by comparing the radiation spectrum with that of a GaN/Si HEMT.

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48

Yu, Shao-wei, and 游紹瑋. "Nonlinear Characteristics of InGaAs PHEMT with Volterra Series Analysis." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/qzv9zh.

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碩士
國立中山大學
電機工程學系研究所
97
This thesis studies the nonlinear characteristics of microwave devices by Volterra series because it can analyze the nonlinear devices with memory. And a nonlinear model was established by measurement data for Volterra series analysis. This content is composed of three parts. The first part devote to introduce the nonlinear phenomenon and theories of nonlinear analysis. The difference between power series and Volterra series could be realized by deriving them. The second part is to introduce the physical characteristics of pHEMTs and demonstrate the procedure of establishing small signal model and fitting nonlinear equations of currents and capacitances, and a process of nonlinear model analysis by Volterra series is shown. The third part is to describe the experimental arrangements and analyze nonlinear characteristics of pHEMTs actually with above methods. And the relationship among nonlinear sources was discussed. The device was fabricated by WIN 0.15μm InGaAs process and measured by on wafer measurements.

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49

Cheng-YenChen and 陳正彥. "Yield Improvement of pHEMT by Gate Photo-Resist Process Modification." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/00637607208889787073.

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碩士
國立成功大學
工程科學系專班
98
GaAs semiconductor is an important component in wireless and optical fiber communications. Over 60% of GaAs’s IC chips are used in mobile power amplifiers worldwide. Hence GaAs plays an important role in mobile power amplifier components. This research uses negative PR resists for the pHEMT gate photolithography process development to make the process stable and to increase the yield. From the photolithography process principle, as negative PR resist exposure energy gets smaller, the thickness of PR becomes smaller after developing (i.e. larger PR resist thickness loss);gate ADM CD also gets larger. Besides, by changing the exposure map,the exposure throughput is increased and the locally defocusing issue of the wafer edge ugly dies is reduced. In addition, by changing the process step after exposure bake, the Gate ADM CD is greatly influenced. This study found the characteristics difference of negative PR resists affected by the process steps. By following the rules obtained for the development of new gate process, the process development speed can be reduced and the process stability can be improved.

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50

Tseng, Min-Nan, and 曾敏男. "Epitaxial technology for the monolithic integration of HBT and PHEMT." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/98107253636103144981.

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碩士
國立臺灣大學
電子工程學研究所
97
We have investigated the optimal growth conditions for integrating heterojunction bipolar transistors (HBTs) and pseudomorphic high electron mobility transistors (PHEMTs) together by metal-organic chemical vapor depositon (MOCVD). In the structure of HBT and PHEMT (BiFET), AlGaAs PHEMT is at the bottom, while InGaP HBT is on the top. The HBT and PHEMT share a heavily n-doped GaAs layer that serves as the cap of the PHEMT and the subcollector of the HBT simultaneously. A heavily n-doped InGaP layer under the HBT subcollector layer is used as an etching-stop layer for controlling the deepness of the gate recess during the PHEMT process. Through the investigation using capacitance-voltage measurement, van der Pauw measurement, high resolution secondary ion mass spectrometry, and photoluminescence and x-ray diffraction measurement, we found that the thermal cycle of InGaP HBT results in the out-diffusion of Si in the heavily doped InGaP layer and donor layer, leading to the increment in the sheet electron density and the decrement in the electron mobility, both degrading the performance of the PHEMT. After lowering the growth temperature of the HBT, Si out-diffusion is inhibited, which brings about the performance recovery of the PHEMT. Though the temperature is reduced, the DC characteristics of the HBT are still as good as those of the HBT grown at high temperature.

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