Cardiff model utilization for predicting the response of multiple-input power amplifiers

This paper explores the use of the Cardiff non-linear behavioral model to characterize the response of multiple-input power amplifiers. In particular, a case study is presented on a 300 W load modulated balanced amplifier operating at 2.1 GHz. The model mathematical formulation is presented, and the comparison between original data and model shows an error below 3%. More importantly, it is shown that the model can accurately interpolate between characterization points allowing a reduction of up to 96% of the points needed to accurately predict the model behavior. This significantly reduces the simulation and measurement time for multiple-input PA's whilst attempting to determine the optimal driving conditions

Survey on individual components for a 5 GHz receiver system using 130 nm CMOS technology

La intención de esta tesis es recopilar información desde un punto de vista general sobre los diferentes tipos de componentes utilizados en un receptor de señales a 5 GHz utilizando tecnología CMOS. Se ha realizado una descripción y análisis de cada uno de los componentes que forman el sistema, destacando diferentes tipos de configuraciones, figuras de mérito y otros parámetros. Se muestra una tabla resumen al final de cada sección, comparando algunos diseños que se han ido presentando a lo largo de los años en conferencias internacionales de la IEEE.The intention of this thesis is to gather information from an overview point about the different types of components used in a 5 GHz receiver using CMOS technology. A review of each of the components that form the system has been made, highlighting different types of configurations, figure of merits and parameters. A summary table is shown at the end of each section, comparing many designs that have been presented over the years at international conferences of the IEEE.Departamento de Ingeniería Energética y FluidomecánicaGrado en Ingeniería en Electrónica Industrial y Automátic

Design and analysis of wideband passive microwave devices using planar structures

A selected volume of work consisting of 84 published journal papers is presented to demonstrate the contributions made by the author in the last seven years of his work at the University of Queensland in the area of Microwave Engineering. The over-arching theme in the author’s works included in this volume is the engineering of novel passive microwave devices that are key components in the building of any microwave system. The author’s contribution covers innovative designs, design methods and analyses for the following key devices and associated systems: Wideband antennas and associated systems Band-notched and multiband antennas Directional couplers and associated systems Power dividers and associated systems Microwave filters Phase shifters Much of the motivation for the work arose from the desire to contribute to the engineering o

Broadband Doherty Power Amplifiers with Enhanced Linearity for Emerging Radio Transmitters

The ever-increasing demand for utilizing wireless spectra has led to development of spectrally efficient radio systems. While these systems offer much higher data throughput, they employ more sophisticated modulation schemes, which result in wideband signals with high peak-to-average power ratios. These signal characteristics significantly complicate the design of RF transmitters, particularly power amplifiers, in terms of power efficiency and linearity requirements. Furthermore, upcoming wireless standards, such as long term evolution advanced (LTE-A) require adoption of carrier aggregation which incorporates multiple component carriers to yield aggregated channels of larger bandwidth (up to 100 MHz). On the other hand, the emerging systems are expected to support legacy standards with minimum area, cost, and power overhead, and thus call for highly-efficient linear broadband power amplifiers capable of efficiently amplifying concurrent modulated signals located over a broad carrier frequency range. This thesis focuses on Doherty power amplifiers (DPAs) with extended high-efficiency range, enhanced bandwidth and improved linearity as a solution for high-efficiency multi-band multi-standard transmitters. It addresses three major concerns associated with DPAs, namely, back-off efficiency, bandwidth, and linearity. The Thesis begins with a detailed theoretical analysis of two-way and three-way Doherty configurations from which the governing equations are derived. This is followed by a comprehensive study of bandwidth limitation in DPA variants. As the first contribution, it is shown that the two existing three-way Doherty structures, i.e., conventional and modified DPAs have inherently broadband characteristics and thus are promising solutions for multi-standard base station transmitters. As a proof of concept, a 30-W three-way modified Doherty amplifier was designed and implemented using packaged GaN transistors over 0.73-0.98 GHz. The prototype was successfully linearized under modulated signals with up to 20 MHz modulation bandwidth. To further improve the linearizability of the DPAs under wideband and multi-band modulated signals, this thesis investigates major sources of static and dynamic nonlinearity in two-way DPAs both at device and circuit levels and explores circuit techniques to mitigate them. Furthermore, the challenges of applying the Doherty technique for concurrent transmission of multiple modulated signals are tackled. The most significant contribution of this thesis is to develop a novel waveform engineering approach to designing ultrawideband DPAs. This approach completely reformulates the DPA's output combiner conditions in order to accommodate complex-valued load modulation. Moreover, it relaxes the harmonic termination requirements of the DPAs to further enlarge the Doherty design space, thereby enhancing the bandwidth. A 50-W waveform-engineered two-way DPA prototype was designed for 1.5-2.5 GHz range and was successfully linearized under intra- and inter-band carrier-aggregated signals with up to 600 MHz carrier spacing. Lastly, an input matching network design methodology is proposed for broadband DPAs. This methodology uses the novel concept of ``current contours'' to minimize the bandwidth, efficiency and linearity degradation of DPAs caused by device input non-idealities

Broadband High-Efficiency Power Amplifier with Quasi-Elliptic Low-Pass Response

© 2013 IEEE. This paper presents a broadband high-efficiency harmonic-tuned power amplifier (PA) with quasi-elliptic low-pass responses. A combination of continuous Class-F-1 and extended continuous Class-F PA modes is employed to significantly expand the design space. A quasi-elliptic low-pass matching network is proposed, which can realize a broadband impedance matching in the predefined optimal impedance region desired by the combination of PA modes. Furthermore, two transmission zeros are generated near the passband, exhibiting high skirt selectivity and providing rapid impedance transition from the passband to the stopband. A wide stopband covering up to the third harmonic is achieved which shows good harmonic suppression. Design procedures of the proposed broadband PA are presented. To verify the proposed methodology, the broadband PA is fabricated and measured. The implemented PA achieves a bandwidth of 145.2% from 0.5 to 3.15 GHz. Over this frequency range, the drain efficiency is measured as 58-74.9% with the output power of greater than 39.03 dBm and a large signal gain ranging from 8.43 to 15.67 dB. A wide stopband is realized from 3.4 to 10 GHz, showing excellent quasi-elliptic low-pass responses. The measured adjacent leakage ratios (ACLRs) using a 20-MHz LTE signal with digital pre-distortion are below -45.06 dBc

Broadband Linearity-Enhanced Doherty Power Amplifier Design Techniques for 5G Sub-6 GHz Applications

The recently deployed fifth generation (5G) cellular networks represent a significant technological advancement over fourth generation (4G) networks. Specifically, new 5G frequency bands were allocated at sub-6 GHz and instantaneous signal bandwidths were increased to satisfy the rapidly growing needs for increased data rates. Furthermore, 5G uses more complex modulation schemes to improve spectrum efficiency. Finally, 5G introduced massive multiple input multiple output (MIMO), where multiple transceivers are used to direct the signal towards specific users, increasing channel capacity. Conventional power amplifiers (PAs) are not suitable for 5G applications due to the increased signal and system complexity. For example, the Doherty power amplifier (DPA) technique is popular since DPAs can efficiently amplify signals with complex modulation schemes, but conventional DPAs have narrow bandwidth and poor linearity that preclude their use in 5G systems. This motivated research into DPA bandwidth and linearity improvements for use in 5G networks. This work focuses on bandwidth and linearity enhancement for sub-6 GHz DPAs realized using discrete components on a printed circuit board (PCB). Bandwidth is improved using broadband architectures for the DPA output combiner network (OCN), the absorption of drain parasitics, and broadband input matching network (IMN) design. Linearity is enhanced by proper drain biasing network design, and careful selection of transistor source impedances. A 3.3–5.0 GHz DPA using these techniques is designed and fabricated. Under wideband modulated signal excitation, the DPA offers very good linearity with appropriate digital predistortion (DPD). A 2×2 array of DPAs is evaluated in fully digital MIMO setup using a 2×2 antenna array. The DPA array achieves excellent linearity characteristics under 100 MHz signals and use of dual-input single-output (DISO) DPD. The DPA remains the ideal choice in 5G MIMO systems when compared to the class AB PA since it can maintain a higher average drain efficiency and similar linearity

Microwave Sensing and Imaging

In recent years, microwave sensing and imaging have acquired an ever-growing importance in several applicative fields, such as non-destructive evaluations in industry and civil engineering, subsurface prospection, security, and biomedical imaging. Indeed, microwave techniques allow, in principle, for information to be obtained directly regarding the physical parameters of the inspected targets (dielectric properties, shape, etc.) by using safe electromagnetic radiations and cost-effective systems. Consequently, a great deal of research activity has recently been devoted to the development of efficient/reliable measurement systems, which are effective data processing algorithms that can be used to solve the underlying electromagnetic inverse scattering problem, and efficient forward solvers to model electromagnetic interactions. Within this framework, this Special Issue aims to provide some insights into recent microwave sensing and imaging systems and techniques