Doctor of Philosophy

dissertationHigh speed wireless communication systems (e.g., long-term evolution (LTE), Wi-Fi) operate with high bandwidth and large peak-to-average power ratios (PAPRs). This is largely due to the use of orthogonal frequency division multiplexing (OFDM) modulation that is prevalent to maximize the spectral efficiency of the communication system. The power amplifier (PA) in the transmitter is the dominant energy consumer in the radio, largely because of the PAPR of the input signal. To reduce the energy consumption of the PA an amplifier that simultaneously achieves high efficiency and high linearity. Furthermore, to lower the cost for high volume production, it is desirable to achieve a complete System-on-Chip (SoC) integration. Linear amplifiers (e.g., Class-A, -B, -AB) are inefficient when amplifying signals with large PAPR that is associated by high peak-to-average modulation techniques such as LTE. OFDM. Switching amplifiers (e.g., Class-D, -E, -F) are very promising due to their high efficiency when compared to their linear amplifier counterparts. Linearization techniques for switching amplifiers have been intensively investigated due to their limited sensitivity to the input amplitude of the signal. Deep-submicron CMOS technology is mostly utilized for logic circuitry, and the Moore's law scaling of CMOS optimizes transistors to operate as high-speed and low-loss switches rather than high gain transistors. Hence, it is advantageous to use transistors in switching mode as switching amplifies and use high-speed digital logic circuitry to implement linearization systems and circuitry. In this work, several linearization architectures are investigated and demonstrated. An envelope elimination and restoration (EER) transmitter that comprises a class-E power amplifier and a 10-bit digital-to-analog converter (DAC) controlled current modulator is investigated. A pipelined switched-capacitor DAC is designed to control an open-loop transconductor that operates as a current modulator, modulating the amplitude of the current supplied to a class-E PA. Such a topology allows for increased filtering of the quantization noise that is problematic in most digital PAs (DPA). The proposed quadrature and multiphase architecture can avoid the bandwidth expansion and delay mismatch associated with polar PAs. The multiphase switched capacitor power amplifier (SCPA) was proposed after the quadrature SCPA and it significantly improves the power efficiency

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

RF-CMOS Switched-Capacitor Power Amplifier for NB-IoT RF transceivers

The increasing market of Narrowband Internet of Things (NB-IoT) applications brings new challenges and constrains in the design of fully integrated transmission architectures, capable of delivering the desired output power with the highest efficiency and linearity, ensuring the longest battery lifetime of the devices. This work is focused on the study and implementation of the most power consuming block within the transmission chain: the Power Amplifier (PA). In this regard, a Switched Capacitor Power Amplifier (SCPA) is designed to operate at a frequency of 0.9 GHz and aiming the maximum output power allowed by the standard of 23 dBm. The final architecture includes a matching network that connects to eight unit PA cells through an LC filter. Each unit PA cell is made of a cascoded class-D PA, two drivers, a level shifter and two selection logic blocks. All the blocks were developed using RF components from a UMC 130nm CMOS process with a 1.2V/2.4V supply voltage. The results show that the architecture is able to produce a maximum output power of 15.61 dBm with a maximum Power Added Efficiency (PAE) of 26.52% and a Total Harmonic Distortion (THD) of 0.68%. In the same conditions, the measured HD2 and HD3 are of -70.23dBc and -43.41dBc, respectively. Additionally, a modulation stage was implemented in VerilogA in order to evaluate the impact of sending different symbols in the SCPA performance. The block, designed for a 16 QAM modulation, is responsible for generating both the number of unit PA cells to be selected and the phase of the clock connected to each PA cell, depending on the amplitude and phase of the constellation points being transmitted.O mercado crescente de aplicações IoT de largura de banda estreita coloca novos desafios e restrições no desenvolvimento de arquiteturas de transmissão totalmente integradas, capazes de produzir a potência desejada com o máximo de eficiência e linearidade possí- veis, de forma a garantir o maior tempo de vida de bateria dos dispositivos. Este trabalho foca-se no estudo e implementação do bloco da cadeia de transmissão que mais consome: o amplificador de potência. Neste sentido, um amplificador de potência de condensadores comutados é desenhado para operar à frequência de 0.9GHz com o objetivo de produzir à sua saída o valor de potência máxima permitida pelo standard de 23dBm. A arquitetura inclui uma malha de adaptação que liga a oito PAs unitários através de um filtro LC. Cada PA unitário consiste num amplificador de potencia class-D cascoded, dois drivers, um level shifter e dois blocos de lógica de seleção. Todos estes blocos foram desenvolvidos usando componentes RF da tecnologia CMOS 130nm da UMC com uma tensão de alimentação de 1.2V/2.4V. Os resultados mostram que a arquitetura é capaz de produzir uma potência à saída de 15.61dBm, com uma PAE de 26.52% e uma distorção harmónica total de 0.68%. Nas mesmas condições, os valores medidos da HD2 e HD3 são de -70.23dBc e -43.41dBc, respetivamente. Adicionalmente, um andar de modulação foi implementado em VerilogA, de forma a avaliar o impacto de enviar diferentes símbolos na performance do amplificador. Este bloco, desenvolvido para uma modulacao 16QAM, é responsável por gerar o número de unidades de PA a serem selecionados e o relógio de fase que liga a cada PA unitário, dependendo da amplitude e fase dos pontos da constelação a serem transmitidos

Wideband CMOS Data Converters for Linear and Efficient mmWave Transmitters

With continuously increasing demands for wireless connectivity, higher\ua0carrier frequencies and wider bandwidths are explored. To overcome a limited transmit power at these higher carrier frequencies, multiple\ua0input multiple output (MIMO) systems, with a large number of transmitters\ua0and antennas, are used to direct the transmitted power towards\ua0the user. With a large transmitter count, each individual transmitter\ua0needs to be small and allow for tight integration with digital circuits. In\ua0addition, modern communication standards require linear transmitters,\ua0making linearity an important factor in the transmitter design.In this thesis, radio frequency digital-to-analog converter (RF-DAC)-based transmitters are explored. They shift the transition from digital\ua0to analog closer to the antennas, performing both digital-to-analog\ua0conversion and up-conversion in a single block. To reduce the need for\ua0computationally costly digital predistortion (DPD), a linear and wellbehaved\ua0RF-DAC transfer characteristic is desirable. The combination\ua0of non-overlapping local oscillator (LO) signals and an expanding segmented\ua0non-linear RF-DAC scaling is evaluated as a way to linearize\ua0the transmitter. This linearization concept has been studied both for\ua0the linearization of the RF-DAC itself and for the joint linearization of\ua0the cascaded RF-DAC-based modulator and power amplifier (PA) combination.\ua0To adapt the linearization, observation receivers are needed.\ua0In these, high-speed analog-to-digital converters (ADCs) have a central\ua0role. A high-speed ADC has been designed and evaluated to understand\ua0how concepts used to increase the sample rate affect the dynamic performance

Vidutinių dažnių 5G belaidžių tinklų galios stiprintuvų tyrimas

This dissertation addresses the problems of ensuring efficient radio fre-quency transmission for 5G wireless networks. Taking into account, that the next generation 5G wireless network structure will be heterogeneous, the device density and their mobility will increase and massive MIMO connectivity capability will be widespread, the main investigated problem is formulated – increasing the efficiency of portable mid-band 5G wireless network CMOS power amplifier with impedance matching networks. The dissertation consists of four parts including the introduction, 3 chapters, conclusions, references and 3 annexes. The investigated problem, importance and purpose of the thesis, the ob-ject of the research methodology, as well as the scientific novelty are de-fined in the introduction. Practical significance of the obtained results, defended state-ments and the structure of the dissertation are also included. The first chapter presents an extensive literature analysis. Latest ad-vances in the structure of the modern wireless network and the importance of the power amplifier in the radio frequency transmission chain are de-scribed in detail. The latter is followed by different power amplifier archi-tectures, parameters and their improvement techniques. Reported imped-ance matching network design methods are also discussed. Chapter 1 is concluded distinguishing the possible research vectors and defining the problems raised in this dissertation. The second chapter is focused around improving the accuracy of de-signing lumped impedance matching network. The proposed methodology of estimating lumped inductor and capacitor parasitic parameters is dis-cussed in detail provi-ding complete mathematical expressions, including a summary and conclusions. The third chapter presents simulation results for the designed radio fre-quency power amplifiers. Two variations of Doherty power amplifier archi-tectures are presented in the second part, covering the full step-by-step de-sign and simulation process. The latter chapter is concluded by comparing simulation and measurement results for all designed radio frequency power amplifiers. General conclusions are followed by an extensive list of references and a list of 5 publications by the author on the topic of the dissertation. 5 papers, focusing on the subject of the discussed dissertation, have been published: three papers are included in the Clarivate Analytics Web of Sci-ence database with a citation index, one paper is included in Clarivate Ana-lytics Web of Science database Conference Proceedings, and one paper has been published in unreferred international conference preceedings. The au-thor has also made 9 presentations at 9 scientific conferences at a national and international level.Dissertatio

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

The Design and Linearization of 60GHz Injection Locked Power Amplifier

The RF power amplifier is one of the most critical blocks of transceivers, as it is expected to provide a suitable output power with high gain, efficiency and linearity. In this paper, a 60-GHz power amplifier based on an injection locked structure is demonstrated in a standard 65 CMOS technology. The PA core consists of a cross-coupled pair of NMOS transistors with an NMOS current source. This structure can achieve large output power and high PAE, but with poor linearity performance. In order to improve the linearity, several linearization techniques are investigated, including adaptive biasing and predistortion. The results show that the adaptive biasing technique can enlarge the linear operation region, but results in poor AM-PM performance. By instead using the predistortion technique, the AM-PM performance can be improved, but the linear region only extends slightly. Considering theses two techniques different advantages, we combine them together to improve not only the linear region but also the AM-PM performance. Finally, a common source amplifier is added as the first stage. With proper bias, the linear operation region is then effectively extended by 7.3 dB. This two stage power amplifier achieves large output power, high linearity and high PAE simultaneously. It delivers a gain of 20dB, a Psat of 16.3dBm, a P1dB of 15.41dBm, and a PAE of 30%.Since the invention of radio-frequency (RF) wireless communication more than 100 years ago, mobile phones and other wireless communications products for civilian consumption have developed rapidly. Nowadays, the demand for larger high data rate and capacities is rising sharply. The traditional wireless bandwidth is no longer able to meet some high-rate applications requirement. However, 60GHz wireless communication system is our solution, and up to 7 GHz unlicensed wide band around 60GHz is open to use across much of the world. Furthermore, the power amplifier (PA) is a critical part of any transmitter to convert the signal to higher power and drive the antenna. For power amplifiers, efficiency and linearity are most important. Power amplifiers with low efficiency will result in high level of heat dissipation. Linearity is a measure of the signal distortion, which consists of gain compression (AM-AM distortion) and phase distortion (AM-PM distortion). In this thesis work, an injection locked power amplifier is used to reduce the input driving requirements and improve the efficiency. Simulations have been performed for implementation in 65nm standard CMOS, which is a low-cost technology for fabrication of integrated circuits (chips). The injection locked technique means that a self-oscillating circuit is forced to run at the same frequency as the input signal. Furthermore, an integrated balun is added to transfer between single-ended and differential signals. The results show that this PA can achieve high efficiency but with poor linearity performance. In order to improve the linearity, different linearization techniques are investigated, including adaptive biasing and predistortion. Adaptive biasing is a feedback technique. At high output levels, the power amplifier has less gain, which leads to signal distortion. The adaptive biasing unit can sense the output power in real time and adjust the bias. The bias is then increased at increased output power in order to restore the power gain at high output levels. Predistortion is another linearization technique. A predistorter, which has a gain expansion characteristic, is then introduced before the PA to compensate for its gain reduction. Then, considering the advantages of these two linearization techniques, we combine them together to achieve even better results. Finally, a two-stage power amplifier is proposed by adding a common source amplifier as the first stage. The first stage can also produce a gain boost at the high output levels, and this expansion gain can be made to match the second-stage gain reduction very well. The simulation results show that the amplifier can achieve high linearity and efficiency at the same time