KEY FRONT-END CIRCUITS IN MILLIMETER-WAVE SILICON-BASED WIRELESS TRANSMITTERS FOR PHASED-ARRAY APPLICATIONS

Millimeter-wave (mm-Wave) phased arrays have been widely used in numerous wireless systems to perform beam forming and spatial filtering that can enhance the equivalent isotropically radiated power (EIRP) for the transmitter (TX). Regarding the existing phased-array architectures, an mm-Wave transmitter includes several building blocks to perform the desired delivered power and phases for wireless communication. Power amplifier (PA) is the most important building block. It needs to offer several advantages, e.g., high efficiency, broadband operation and high linearity. With the recent escalation of interest in 5G wireless communication technologies, mm-Wave transceivers at the 5G frequency bands (e.g., 28 GHz, 37 GHz, 39 GHz, and 60 GHz) have become an important topic in both academia and industry. Thus, PA design is a critical obstacle due to the challenges associated with implementing wideband, highly efficient and highly linear PAs at mm-Wave frequencies. In this dissertation, we present several PA design innovations to address the aforementioned challenges. Additionally, phase shifter (PS) also plays a key role in a phased-array system, since it governs the beam forming quality and steering capabilities. A high-performance phase shifter should achieve a low insertion loss, a wide phase shifting range, dense phase shift angles, and good input/output matching.Ph.D

A review of technologies and design techniques of millimeter-wave power amplifiers

his article reviews the state-of-the-art millimeter-wave (mm-wave) power amplifiers (PAs), focusing on broadband design techniques. An overview of the main solid-state technologies is provided, including Si, gallium arsenide (GaAs), GaN, and other III-V materials, and both field-effect and bipolar transistors. The most popular broadband design techniques are introduced, before critically comparing through the most relevant design examples found in the scientific literature. Given the wide breadth of applications that are foreseen to exploit the mm-wave spectrum, this contribution will represent a valuable guide for designers who need a single reference before adventuring in the challenging task of the mm-wave PA design

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

Class-E Power Amplifiers in Modern RF Transmitters

Power amplifiers have been playing a vital role in most wireless communication systems. In order to improve efficiency of wireless systems, advanced transmitter architectures, such as Doherty amplifiers, outphasing amplifiers, supply voltage modulation techniques are widely used. The goal of this work is to develop novel techniques for building load modulation transmitters based on class-E power amplifiers. The first contribution is an analytical model for derivation load network parameters. The proposed model derives the parameters for both the peak and back-off power levels providing high efficiency. The proposed model demonstrates, that class-E PA with shunt capacitance and shunt filter is capable of providing high drain efficiency for back-off output power levels. The second contribution is a design of a wideband class-E power amplifier (PA) with shunt capacitance and shunt filter. The broadband operation has been achieved by application of the double reactance compensation technique. Simulated and experimental results are presented. The performance of the fabricated PA is compared with existing wideband PAs. The third contribution is application of the proposed technique to outphasing PA design. The designed outphasing PA was optimized, fabricated and tested. A possibility to extend the operational bandwidth of the PA is considered. Also the application of the proposed technique to Doherty PA design is demonstrated. The fourth contribution is linearization of outphasing PA. Firstly, an analytical model describing the nonlinearity of nonisolated combiners under amplitude imbalance is presented. Secondly, a novel phase-only predistortion technique for class-E outphasing PAs is proposed. Thirdly, linearization of the fabricated outphasing PA based on memory polynomial model is demonstrated using a 64QAM OFDM modulated signal with 20 MHz bandwidth. Overall, this work provides novel techniques for load modulation transmitter design based on class-E power amplifiers with shunt capacitance and shunt filter

High-Efficiency Millimeter-Wave Front-Ends for Large Phased-Array Transmitters

The ever-increasing demand for wireless broadband connectivity requires infrastructure capable of supporting data transfer rates at multi-Gbps. To accommodate such heavy traffic, the channel capacity for the given spectrum must be utilized as efficiently as possible. Wideband millimeter-wave phased-array systems can enhance the capacity of the channel by providing multiple steerable directional beams. However the cost, complexity, and high power consumption of phased-array systems are key barriers to the commercialization of such technology. Silicon-based beam-former chips and scalable phased-array technology offer promising solutions to lower the cost of phased-array systems. However, the implementation of low-power phased-array architectures is still a challenge. Millimeter-wave power generation in silicon beam-formers suffers from low efficiency. The stringent linearity requirements for multi-beam wideband arrays further limits the achievable efficiency. In scalable phased-arrays, each module consists of an antenna sub-array and a beam-former chip that feeds the antenna elements. To improve efficiency, a design methodology that considers the beam-former chip and the antenna array as one entity is necessary. In this thesis, power-efficient solutions for a millimeter-wave phased-array transmitter are studied and different high-efficiency power amplifier structures for broadband applications are proposed. Initially, the design of a novel 27-30 GHz RF front-end consisting of a variable gain amplifier, a 360 degree phase shifter, and a two-stage linear power amplifier with output power of 12 dBm is described. It is fabricated using 0.13 $\mu m$ SiGe technology. This chip serves as the RF core of a beam-former chip with eight outputs for feeding a 2$\times$2 dual-feed sub-array. Such sub-arrays are used as part of large phased-arrays for SATCOM infrastructure. Measurement results show 26.7 \% total efficiency for the designed chip. The chip achieves the highest efficiency among Ka-band phased-array transmitters reported in the literature. In addition, original transformer-based output matching structures are proposed for harmonic-tuned power amplifiers. Harmonic-tuned power amplifiers have high peak-efficiency but their complicated output matching structure can limit their use in beam-former RF front-ends. The proposed output matching structures have the layout footprint of a transformer, making their use in beam-former chips feasible. A 26-38 GHz power amplifier based on a non-inverting 1:1 transformer is fabricated. A measured efficiency of more than 27 \% is achieved across the band with an output power of 12 dBm. Furthermore, two continuous class $F^{-1}$ power amplifiers using 1:1 inverting transformers are described. Simulation results show a peak-efficiency of 35 \% and output power of 12 dBm from 24 to 30 GHz. A common-base power amplifier with inverting transformer output matching is also demonstrated. This amplifier achieves a peak-efficiency of 42 \% and peak output power of 16 dBm. Finally, a low-loss Ka-band re-configurable output matching structure based on tunable lines is proposed and implemented. A double-stub matching structure with three tunable segments is proposed to maximize the impedance matching coverage. This structure can potentially compensate for the antenna impedance variation in phased-array antennas