Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications
Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications
Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar ApplicationsFrancesco FornettiA dissertation submitted to the Univ Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications versity of Bristol in accordance with the requirements for award of the degree of Doctor of Philosophy in the Faculty of EngineeringDepartment of Electrical and Electronic Engineering40513AbstractNew bandgap semiconductor materials, such as Gallium Nitride (GaN), promise to revolutionise the world o Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications f microwave power amplifiers by providing high power density, linear operation and robustness up to Ka-band frequencies (35GHz). Applications which reCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications
quire very high RF powers still utilise vacuum tube devices, thus a breakthrough in semiconductor technology is long overdue. Nevertheless, despite thCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar ApplicationsFrancesco FornettiA dissertation submitted to the Univ Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications her lll-v alloys from achieving the performance and reliability levels required. In addition, some of these issues, such as trapping effects, may be exacerbated when the devices are operated in pulsed mode as is done in Radar systems. A number of studies have investigated both commercial and prototy Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications pe GaN devices in Continuous Wave (CW) mode. This thesis addresses the suitability of such devices to pulsed applications and provides corrective expeCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications
rimental characterisation and recommendations.In this thesis, a thorough analysis of physics, technology and research status of GaN High Electron MobiCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar ApplicationsFrancesco FornettiA dissertation submitted to the Univ Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications ntly subjected to extensive investigations both in the frequency and time domain. Such tests aim at verifying the presence of possible trapping effects and their effect on the performance of pulsed GaN amplifiers. New measures, as Spectral Asymmetry and spectrum-derived Pulse Width Variation, are al Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications so introduced which may be useful performance indicators for pulsed amplifiers and be of aid to device manufacturers and circuit designers. In additioCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications
n, device level tests are also carried out on both Cree and Nitronex devices which investigate the presence of the trapping effects, and their influenCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar ApplicationsFrancesco FornettiA dissertation submitted to the Univ Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications icant trapping effects are present in commercially available devices and, more importantly, that they have much longer time constants (10s and 100s of seconds) than are encountered in other technologies such as GaAs (ms). An appropriate characterisation setup is therefore required, at device level, Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications in order to obtain meaningful l-V characteristics. Operational parameters such as pulse repetition frequency and duty cycle were also found to affectCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications
the l-V characteristic of the devices and should therefore be taken into account when designing pulsed amplifiers.It was also observed that the perforCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar ApplicationsFrancesco FornettiA dissertation submitted to the Univ Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications quencies (PRFs) and power levels. This demonstrates that such GaN devices may be suitable for Radar applications. Nevertheless, when the amplifiers were pushed to higher drive levels, a considerable increase in fall time was observed which was chiefly due to third order non-linearites and could be m Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications odelled by means of third order polynomials. In addition, the new performance measures introduced were found to be very useful in the selection of appCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications
ropriate bias points for the transistor. An appropriate choice of bias was found to considerably improve the performance of a pulsed amplifier in termCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar ApplicationsFrancesco FornettiA dissertation submitted to the Univ Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications her frequency amplifiers which have recently become available.IIAcknowledgementsFirst and foremost I would like to thank Prof Mark Beach for offering this wonderful opportunity to me, establishing the liaisons with MBDA and procuring the funding for my Ph.D. I would also like to thank him for being Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications very understanding and supportive particularly through the difficult times. I am also thankful to Dr Kevin Morris for being my supervisor and for beinCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications
g engaging in our meetings and discussions.Iwould also like to thank Chris Carter and MBDA for their support and help and for the interest and admiratCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar ApplicationsFrancesco FornettiA dissertation submitted to the Univ Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications s way to look after me during my time in Australia. Not only did he give me the opportunity to greatly further my technical knowledge but he also ensured that I was fully integrated in the teaching and research community of Sydney and Macquarie Universities.Mr Ken Stevens deserves a really special m Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications ention for his help and support on both a technical and personal level. His encouragement and technical know-how were key to the successful realisatioCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications
n of the test setups used for the experiments.I am also very grateful to Prof McGeehan for his advice and encouragement and for his support and praiseCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar ApplicationsFrancesco FornettiA dissertation submitted to the Univ Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications ulation tools, Cree Inc and Nitronex for supplying free samples and Marco Brunetti for his help with the graphics.In addition there are no words to express my gratitude to my dearest friends Magnus and Roger who were always there for me through all the adversities that life challenged me with in the Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications last four years. Without their help, encouragement and support I could not have achieved this.IllAuthor's DeclarationI declare that the work in thisCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications
dissertation was carried out in accordance with the requirements of the University's Regulations and Code of Practice for Research Degree Programmes aCharacterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar ApplicationsFrancesco FornettiA dissertation submitted to the Univ Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications own work. Work done in collaboration with, or with the assistance of, others, IS indicated as such. Any views expressed in the dissertation are those of the author.SIGNED:DATE:IVTable of Contents1Introduction..........................................................................11.1Solid State Po Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications wer Amplifiers and Radar Transmitters................................11.2Monopulse Radar..............................................................Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications
......51.3Key Objectives.....................................................................81.4Overview of the Research Work........................Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar ApplicationsFrancesco FornettiA dissertation submitted to the Univ Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications eterojunctions.........................................122.1Introduction......................................................................12Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar ApplicationsFrancesco FornettiA dissertation submitted to the UnivGọi ngay
Chat zalo
Facebook