Design Of Power Scalable Gallium Nitride Class E Power Amplifiers

The need for high power, highly efficient, multi-band and multi-mode radio frequency (RF) and microwave power amplifiers in the commercial and defense wireless industries continues to drive the research and development of gallium nitride (GaN) devices and their implementation in the receiver and transmitter lineups of modern microwave systems. Unlike silicon (Si) or gallium arsenide (GaAs), GaN is a direct wide bandgap semiconductor that permits usage in high voltage and therefore high power applications. Additionally, the increased saturation velocity of GaN allows for operation well into the super high frequency (SHF) portion of the RF spectrum. For the power amplifier designer, active devices utilizing GaN will exhibit power densities almost an order of magnitude greater than comparably sized GaAs devices and almost two orders of magnitude greater than Si devices. Not only does this mean an overall size reduction of an amplifier for a given output power, but it allows GaN to replace specialized components such as the traveling-wave tube (TWT) and other circuits once deemed impossible to realize using solid-state electronics. Designs utilizing GaN in amplifiers, switches, mixers, etc., are able to meet the continually shrinking size, increased power, stringent thermal, and cost requirements of a modern microwave system.There are two relatively straight forward methods used to investigate the intrinsic power scaling properties of a GaN high-electron-mobility transistor (HEMTs) configured as a common source amplifier. The first method involves sweeping the applied drain to source voltage bias and the second method involves scaling the physical size of the transistor. The prior method can be used to evaluate fixed sized transistors while the latter method requires an understanding of the obtainable power density for a given device technology prior to fabrication. Since the power density is also a function of the drain to source voltage bias, an initial iterative component of the design cycle may be required to fully characterize the device technology. If a scalable nonlinear device model is available to the designer, the harmonic balance simulator in most computer aided design (CAD) tools can be used to evaluate device parameters such as the maximum output power and power added efficiency (PAE) using large signal load pull simulations.The circuits presented in this thesis address two power amplifier design approaches commonly used in industry. The first approach utilizes commercially available bare die GaN transistors that can be wire-bonded to matching circuitry on a printed circuit board (PCB). This technique is known as hybrid packaging. The second approach utilizes a fully integrated design or monolithic microwave integrated circuit (MMIC) and the process design kit (PDK) used to design, simulate and layout the power amplifier circuitry before submission to a foundry for fabrication. In both cases, the nonlinear transistor models are used to investigate the power scalability of class E mode GaN power amplifiers and the techniques used to implement such circuits. The design, results, and challenges of each approach are discussed and future work is presented.

The textbook discusses design and analysis of microwave high power and high efficiency amplifiers for communications, appropriate for undergraduate, post-graduate students, practical circuit designers and researchers in the field of electronics and communication engineering. This book covers basics of III-V group semiconductor materials and GaAs and GaN based High Electron Mobility Transistors (HEMTs) most suitable for microwave and mm wave power amplifiers required for present wireless communication systems and upcoming 4G and 5G mobile base stations. The book describes design and analysis of classical class of amplifier operations such as Class-A, B, AB, C and F. The coverage extends to advanced classes of amplifier operation such as extended continuous Class-B/Class-J, and extended continuous Class-F operations for broadband, high power and high efficiency performance. Analytical expressions are derived for circuit elements and performance parameters for clear understanding and required for practical design of power amplifiers. Each topic is supplemented with suitable schematic diagrams, analytical expressions and plotted results for clear understanding.

The modern wireless communication systems require modulated signals with wide modulation bandwidth. This, in turns, requires signals with very high dynamic range and peak-to-average power ratio (PAPR). This means that the amplifier in the base-station has to work at a power back-off as large as the dynamic range of the signal, so that the amplifier has a high linearity in this region. For the standard single-stage amplifiers, this large power back-off reduces the efficiency dramatically. In this work, a three-way Doherty power amplifier (DPA) aiming at high power efficiency within a dynamic range of 9.5 dB, is designed and fabricated using partitioning design approach. The partitioning design approach decomposes a complex design task into small-sized, well-controllable, and verifiable subcircuits. This advanced straight forward method has shown very promising results. Using this design approach, a three-way DPA has been designed to demonstrate the advantages of this reliable design technique as well. Based on the design of a single-stage power amplifier and proposing a novel output power combiner, a 6 W three-way DPA has been designed which allows the mandatory load modulation principle in three-way DPA structures to be realized with simpler elements, whereas the design of a standard Doherty combiner would have been very challenging and not practical due to the extremely small value of its characteristic line impedance. The proposed combiner is calculated for a three-way DPA with 2-mm AlGaN/GaN-HEMTs. The simulation result shows a very good load modulation for the amplifier, which confirms the theoretical expectation for a three-way DPA. The efficiency of the designed 6 W three-way DPA at large back-off shows very promising values compared to recently reported amplifiers. The measured IMD3 products confirm the good linearity of the amplifier as well. Accordingly, the proposed power combiner and the design strategy are recommended to be used as the preferred option for designing three-way DPA structures with very high output power.

This work has arisen out of the strong demand for a superior power-added efficiency (PAE) of AlGaN/GaN high electron mobility transistor (HEMT) high-power amplifiers (HPAs) that are part of any advanced wireless multifunctional RF-system with limited prime energy. Different concepts and approaches on device and design level for PAE improvements are analyzed, e.g. structural and layout changes of the GaN transistor and advanced circuit design techniques for PAE improvements of GaN HEMT HPAs.

This book demonstrates to readers why Gallium Nitride (GaN) transistors have a superior performance as compared to the already mature Silicon technology. The new GaN-based transistors here described enable both high frequency and high efficiency power conversion, leading to smaller and more efficient power systems. Coverage includes i) GaN substrates and device physics; ii) innovative GaN -transistors structure (lateral and vertical); iii) reliability and robustness of GaN-power transistors; iv) impact of parasitic on GaN based power conversion, v) new power converter architectures and vi) GaN in switched mode power conversion. Provides single-source reference to Gallium Nitride (GaN)-based technologies, from the material level to circuit level, both for power conversions architectures and switched mode power amplifiers; Demonstrates how GaN is a superior technology for switching devices, enabling both high frequency, high efficiency and lower cost power conversion; Enables design of smaller, cheaper and more efficient power supplies.

This book gives you – in one comprehensive and practical resource -- everything you need to successfully design modern and sophisticated power amplifiers at mmWave frequencies. The book provides an in-depth treatment of the design methodology for MMIC power amplifiers, then brings you step by step through the various phases of design, from the selection of technology and preliminary architecture considerations, to the effective design of the matching circuits and conversion of electrical-to-electromagnetic models. Detailed figures and numerous practical applications are included to help you gain valuable insights into these technologies and learn to identify the best path to a successful design. You’ll be guided through a range of new mmWave power applications that show particular promise to support new 5G systems, while mastering the use of GaN technology that continues to dominate the power mmWave applications due to its high power, gain, and efficiency. This is a valuable resource for power amplifier design engineers, technicians, industry R&D staff, and anyone getting into the area of power MMICs who wants to learn how to design at mmWave frequencies.

Do you want to know how to design high efficiency RF and microwave solid state power amplifiers? Read this book to learn the main concepts that are fundamental for optimum amplifier design. Practical design techniques are set out, stating the pros and cons for each method presented in this text. In addition to novel theoretical discussion and workable guidelines, you will find helpful running examples and case studies that demonstrate the key issues involved in power amplifier (PA) design flow. Highlights include: Clarification of topics which are often misunderstood and misused, such as bias classes and PA nomenclatures. The consideration of both hybrid and monolithic microwave integrated circuits (MMICs). Discussions of switch-mode and current-mode PA design approaches and an explanation of the differences. Coverage of the linearity issue in PA design at circuit level, with advice on low distortion power stages. Analysis of the hot topic of Doherty amplifier design, plus a description of advanced techniques based on multi-way and multi-stage architecture solutions. High Efficiency RF and Microwave Solid State Power Amplifiers is: an ideal tutorial for MSc and postgraduate students taking courses in microwave electronics and solid state circuit/device design; a useful reference text for practising electronic engineers and researchers in the field of PA design and microwave and RF engineering. With its unique unified vision of solid state amplifiers, you won’t find a more comprehensive publication on the topic.

The importance of wireless communications in today's telecommunications industry is indubitable. Wireless technologies are used in almost every aspect of our everyday life. Universal Mobile Telecommunications System (UMTS) technology has already implemented 3G communication standard for mobile communications. Power amplifiers are the most power consuming unit in wireless communication systems. The power amplifiers used in UMTS devices need to be highly efficient. Improved efficiency not only extends the battery life but also reduces the DC power consumption, transmitter size and weight. Although the power amplifiers used in existing second generation GSM (Global System for Mobile Communications) transmitters are highly efficient, they cannot be applied to UMTS/WCDMA since GSM uses the constant envelope feature of GMSK (Gaussian Minimum Shift Keying) modulation which introduces phase variations only. In UMTS, a WCDMA system with QPSK modulation is used where both phase and amplitude variations are introduced by the modulation. The power amplifiers designed for WCDMA need to satisfy the contradicting operation requirement between linearity and efficiency. In this thesis, a highly efficient class F power amplifier has been designed for WCDMA band with a center frequency of 2.14 GHz and bandwidth of 5 MHz using GaN transistor. The amplifier has been simulated using a high frequency circuit simulator namely, the Agilent Advanced Design System (ADS). The simulated results have shown a Power Added Efficiency (PAE) of 76.8% for an optimum input power of 30 dBm. The amplifier was then fabricated and measured. Measurement has shown a PAE of 75.9% for an optimum input power of 29.6 dBm which is in good accordance with the simulated results. Based on a literature review, and to the best of our knowledge, our circuit exhibited one of the highest measured PAE for a GaN class-F amplifier working at 2.14 GHz. The value of third and fifth order IM products of the designed class F PA is -13 dBc and -21 dBc respectively at peak power and -28.5 dBc and -43 dBc respectively at 6 dB back-off from peak power.