4.5-/4.9-GHz-Band Selective High-Efficiency GaN HEMT Power Amplifier by Characteristic Impedance Switching

A 4.5-/4.9-GHz band-selective GaN HEMT high-efficiency power amplifier has been designed and evaluated for next-generation wireless communication systems. An optimum termination impedance for each high-efficiency operation band was changed by using PIN diodes inserted into a harmonic treatment circuit at the output side. In order to minimize the influence of the insertion loss of the PIN diodes, an additional line is arranged in parallel with the open-ended stub used for second harmonic treatment, and the line and stub are connected with the PIN diodes to change the effective characteristic impedance. The fabricated GaN HEMT amplifier achieved a maximum power-added efficiency of 57% and 66% and a maximum drain efficiency of 62% and 70% at 4.6 and 5.0GHz, respectively, with a saturated output power of 38dBm, for each switched condition

Radio Frequency Interference /RFI/ design guide for aerospace communications systems

Radio frequency interference design guide for aerospace communications system

Design of a class-F power amplifier with reconfigurable output harmonic termination in 0.13 µm CMOS

Next generation wireless communication technology requires mobile devices and base stations to support multiband multimode frequencies with higher data rate because of the type of enriched and enhanced features and services that are provided to the end user. The challenge for next generation PA designers is to provide high efficiency, output power and good linearity across multiple frequency bands, modulation standards and bandwidth. Current industry solution involves parallel PAs dedicated to a single band of operation. As more and more features are added, more and more PAs will be required with increasing cost, area and complexity. As a solution to this problem, one tunable fully integrated class-F power amplifier with reconfigurable output harmonic termination is proposed, designed, fabricated and tested with a commercially available 0.13µm CMOS process technology. By using the coupling between the primary and the secondary winding of an on chip transformer with a variable secondary termination capacitance, the second and third harmonic short and open circuit frequencies are dynamically tuned from 700 MHz to 1200 MHz and achieve high efficiency and output power. To overcome CMOS process low break down voltage, a series voltage combining approach is used for the power device to boost output power, by allowing the power supply to exceed process limits. The fabricated die was packaged and mounted to a printed circuit board for evaluation. Compared to previously publish fully integrated PAs, our design exhibits superior peak power added efficiency, 48.4%, and decent saturated output power and power gain of 24.6 dBm and 16.5 dB respectively with reconfigurability from 700 MHz to 1200 MHz

A Fully-Integrated Reconfigurable Dual-Band Transceiver for Short Range Wireless Communications in 180 nm CMOS

© 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.A fully-integrated reconfigurable dual-band (760-960 MHz and 2.4-2.5 GHz) transceiver (TRX) for short range wireless communications is presented. The TRX consists of two individually-optimized RF front-ends for each band and one shared power-scalable analog baseband. The sub-GHz receiver has achieved the maximum 75 dBc 3rd-order harmonic rejection ratio (HRR3) by inserting a Q-enhanced notch filtering RF amplifier (RFA). In 2.4 GHz band, a single-ended-to-differential RFA with gain/phase imbalance compensation is proposed in the receiver. A ΣΔ fractional-N PLL frequency synthesizer with two switchable Class-C VCOs is employed to provide the LOs. Moreover, the integrated multi-mode PAs achieve the output P1dB (OP1dB) of 16.3 dBm and 14.1 dBm with both 25% PAE for sub-GHz and 2.4 GHz bands, respectively. A power-control loop is proposed to detect the input signal PAPR in real-time and flexibly reconfigure the PA's operation modes to enhance the back-off efficiency. With this proposed technique, the PAE of the sub-GHz PA is improved by x3.24 and x1.41 at 9 dB and 3 dB back-off powers, respectively, and the PAE of the 2.4 GHz PA is improved by x2.17 at 6 dB back-off power. The presented transceiver has achieved comparable or even better performance in terms of noise figure, HRR, OP1dB and power efficiency compared with the state-of-the-art.Peer reviewe

Advanced High Efficiency and Broadband Power Amplifiers Based on GaN HEMT for Wireless Applications

In advanced wireless communication systems, a rapid increase in the mobile data traffic and broad information bandwidth requirement can lead to the use of complex spectrally efficient modulation schemes such as orthogonal frequency-division multiplexing (OFDM). Generally, complex non-constant envelope modulated signals have very high peak-to-average ratios (PAPR). Doherty Power Amplifier (DPA) is the most commonly used power amplifier (PA) architecture for meeting high efficiency requirement in advanced communication systems, in the presence of high PAPR signals. However, limited bandwidth of the conventional DPA is often identified as a bottleneck for widespread deployment in base-station application for multi-standard communication signals. The research in this thesis focuses on the development of new designs to overcome the bandwidth limitations of a conventional PA. In particular, the bandwidth limitation factors of a conventional DPA architecture are studied. Moreover, a novel design technique is proposed for DPA’s bandwidth extension. In the first PA design, limited bandwidth and linearity problems are addressed simultaneously. For this purpose, a new Class-AB PA with extended bandwidth and improved linearity is presented for LTE 5 W pico-cell base-station over a frequency range of 1.9–2.5 GHz. A two-tone load/source-pull and bias point optimization techniques are used to extract the sweet spots for optimum efficiency and linearity from the 6 W Cree GaN HEMT device for the whole frequency band. The realized prototype presented saturated PAE higher than 60%, a power gain of 13 dB and an average output power of 36.5 dBm over the desired bandwidth. The proposed PA is also characterized by QAM-256 and LTE input communication signals for linearity characterization. Measured ACPRs are lower than -40 dBc for an input power of 17 dBm. The documented results indicate that the proposed Class-AB architecture is suitable for pico-cell base-station application. In the second PA design, an inherent bandwidth limitation of Class-F power amplifier forced by the improper load harmonics terminations at multiple harmonics is investigated and analyzed. It is demonstrated that the impedance tuning of the second and third harmonics at the drain terminal of a transistor is crucial to achieve a broadband performance. The effect of harmonics terminations on power amplifier’s bandwidth up to fourth harmonics is investigated. The implemented broadband Class-F PA achieved maximum saturated drain efficiency 60-77%, and 10 W output power throughout (1.1-2.1 GHz) band. The simulated and measured results verify that the presented Class-F PA is suitable for a high-efficiency system application in wireless communications over a wide range of frequencies. In the third PA design, a single- and dual-input DPA for LTE application in the 3.5 GHz frequency band are presented and compared. The main goal of this study is to improve the performance of gallium–nitride (GaN) Doherty transmitters over a wide bandwidth in the 3.5 GHz frequency band. For this purpose, the linearity-efficiency trade-off for the two proposed architectures is discussed in detail. Simulated results demonstrate that the single- and dual-input DPA exhibited a peak drain efficiency (DE) of 72.4% and 77%, respectively. Both the circuits showed saturated output power more than 42.9 dBm throughout the designed band. Saturated efficiency, gain and bandwidth of dual-input DPA are higher than that of the single-input DPA. On the other side, dual-input DPA linearity is worse as compared to the single-input DPA. In the last PA design, a novel design methodology for ultra-wide band DPA is presented. The bandwidth limitation factors of the conventional Doherty amplifier are discussed on the ground of broadband matching with impedance variation. To extend the DPA bandwidth, three different methods are used such as post-matching, low impedance transformation ratio and the optimization of offset line for wide bandwidth in the proposed design. The proposed Doherty power amplifier was designed and realized based on two 10 W GaN HEMT devices from Cree Inc. The measured results exhibited 42-57% of efficiency at the 6-dB back-off and saturated output power ranges from 41.5 to 43.1 dBm in the frequency range of 1.15 to 2.35 GHz (68.5% fractional bandwidth). Moreover, less than -25 dBc ACPRs are measured at 42 dBm peak output power throughout the designed band. In a nutshell, all power amplifiers presented in this thesis are suitable for wideband operation and their performances are satisfying the required operational standard. Therefore, this thesis has a significant contribution in the domain of high efficiency and broadband power amplifiers

A survey on RF and microwave doherty power amplifier for mobile handset applications

This survey addresses the cutting-edge load modulation microwave and radio frequency power amplifiers for next-generation wireless communication standards. The basic operational principle of the Doherty amplifier and its defective behavior that has been originated by transistor characteristics will be presented. Moreover, advance design architectures for enhancing the Doherty power amplifier’s performance in terms of higher efficiency and wider bandwidth characteristics, as well as the compact design techniques of Doherty amplifier that meets the requirements of legacy 5G handset applications, will be discussed.Agencia Estatal de Investigación | Ref. TEC2017-88242-C3-2-RFundação para a Ciência e a Tecnologia | Ref. UIDP/50008/201

High-Power Microwave/ Radio-Frequency Components, Circuits, and Subsystems for Next-Generation Wireless Radio Front-Ends

As the wireless communication systems evolve toward the future generation, intelligence will be the main signature/trend, well known as the concepts of cognitive and software-defined radios which offer ultimate data transmission speed, spectrum access, and user capacity. During this evolution, the human society may experience another round of `information revolution\u27. However, one of the major bottlenecks of this promotion lies in hardware realization, since all the aforementioned intelligent systems are required to cover a broad frequency range to support multiple communication bands and dissimilar standards. As the essential part of the hardware, power amplifiers (PAs) capable of operating over a wide bandwidth have been identified as the key enabling technology. This dissertation focuses on novel methodologies for designing and realizing broadband high-power PAs, their integration with high-quality-factor (high-Q) tunable filters, and relevant investigations on the reliabilities of these tunable devices. It can be basically divided into three major parts: 1.Broadband High-Efficiency Power Amplifiers. Obtaining high PA efficiency over a wide bandwidth is very challenging, because of the difficulty of performing broadband multi-harmonic matching. However, high efficiency is the critical feature for high-performance PAs due to the ever-increasing demands for environmental friendliness, energy saving, and longer battery life. In this research, novel design methodologies of broad-band highly efficient PAs are proposed, including the first-ever mode-transferring PA theory, novel matching network topology, and wideband reconfigurable PA architecture. These techniques significantly advance the state-of-the-art in terms of bandwidth and efficiency. 2.Co-Design of PAs and High-Q Tunable Filters. When implementing the intelligent communication systems, the conventional approach based on independent RF design philosophy suffers from many inherent defects, since no global optimization is achieved leading to degraded overall performance. An attractive method to solve these difficulties is to co-design critical modules of the transceiver chain. This dissertation presents the first-ever co-design of PAs and tunable filters, in which the redundant inter-module matching is entirely eliminated, leading to minimized size & cost and maximized overall performance. The saved hardware resources can be further transferred to enhance system functionalities. Moreover, we also demonstrate that co-design of PAs and filters can lead to more functionalities/benefits for the wireless systems, e.g. efficient and linear amplification of dual-carrier (or multi-carrier) signals. 3.High-Power/Non-Linear Study on Tunable Devices. High-power limitation/power handling is an everlasting theme of tunable devices, as it determines the operational life and is the threshold for actual industrial applications. Under high-power operation, the high RF voltage can lead to failures like tuners\u27 mechanical deflections and gas discharge in the small air spacing of the cavity. These two mechanisms are studied independently with their instantaneous and long-term effects on the device performance. In addition, an anti-biased topology of electrostatic RF MEMS varactors and tunable filters is proposed and experimentally validated for reducing the non-linear effect induced by bias-noise. These investigations will enlighten the designers on how to avoid and/or minimize the non-ideal effects, eventually leading to longer life cycle and performance sustainability of the tunable devices

AlGaN/GaN-HEMT power amplifiers with optimized power-added efficiency for X-band applications

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