Communication Subsystems for Emerging Wireless Technologies

The paper describes a multi-disciplinary design of modern communication systems. The design starts with the analysis of a system in order to define requirements on its individual components. The design exploits proper models of communication channels to adapt the systems to expected transmission conditions. Input filtering of signals both in the frequency domain and in the spatial domain is ensured by a properly designed antenna. Further signal processing (amplification and further filtering) is done by electronics circuits. Finally, signal processing techniques are applied to yield information about current properties of frequency spectrum and to distribute the transmission over free subcarrier channels

Wireless power transmission: R&D activities within Europe

Wireless power transmission (WPT) is an emerging technology that is gaining increased visibility in recent years. Efficient WPT circuits, systems and strategies can address a large group of applications spanning from batteryless systems, battery-free sensors, passive RF identification, near-field communications, and many others. WPT is a fundamental enabling technology of the Internet of Things concept, as well as machine-to-machine communications, since it minimizes the use of batteries and eliminates wired power connections. WPT technology brings together RF and dc circuit and system designers with different backgrounds on circuit design, novel materials and applications, and regulatory issues, forming a cross disciplinary team in order to achieve an efficient transmission of power over the air interface. This paper aims to present WPT technology in an integrated way, addressing state-of-the-art and challenges, and to discuss future R&D perspectives summarizing recent activities in Europe.The work of N. Borges Carvalho and A. J. S. Soares Boaventura was supported by the Portuguese Foundation for Science and Technology (FCT) under Project CREATION EXCL/EEI-TEL/0067/2012 and Doctoral Scholarship SFRH/BD/80615/2011. The work of H. Rogier was supported by BELSPO through the IAP Phase VII BESTCOM project and the Fund for Scientific Research-Flanders (FWO-V). The work of A. Georgiadis and A. Collado was supported by the European Union (EU) under Marie Curie FP7-PEOPLE-2009-IAPP 251557 and the Spanish Ministry of Economy and Competitiveness Project TEC 2012-39143. The work of J. A. García and M. N. Ruíz was supported by the Spanish Ministries MICINN and MINECO under FEDER co-funded Project TEC2011-29126-C03-01 and Project CSD2008-00068. The work of J. Kracek and M. Mazanek was supported in part by the Czech Ministry of Education Youth and Sports under Project OC09075–Novel Emerging Wireless Systems

Power Amplifiers for Electronic Bio-Implants

Healthcare systems face continual challenges in meeting their aims to provide quality care to their citizens within tight budgets. Ageing populations in the developed world are perhaps one of the greatest concerns in providing quality healthcare in the future. The median age of citizens in economically developed regions is set to approach 40 years by the year 2050, and reach as high as 55 years in Japan. This trend is likely to lead to strained economies caused by less revenue raised by smaller workforces. Another effect of ageing populations is the need of further care in order to remain healthy. This care varies from frequent check-ups to condition monitoring, compensation for organ malfunction and serious surgical operations. As a result of these trends, healthcare systems will face the task of servicing more people with more serious and expensive health services, all using less available funds. Effort is being focused on running cheaper and more effective healthcare systems and the development of technology to assist in this process is a natural research priority

Nonlinear analysis of a high-power oscillator inductively coupled to an external resonator

This contribution presents a detailed nonlinear analysis of a high-power oscillator that is inductively coupled to an external resonator for power transfer applications. The analytical formulation of a cubic nonlinearity oscillator enables the derivation of the maximum transferred power and the value of the coupling factor at which the oscillation is extinguished. Then, a simple procedure to obtain a Class-E oscillator from an initial high efficiency oscillator is presented. The solution curves versus the coupling factor and the elements of the external resonator are easily obtained from the extraction of a bi-variate nonlinear admittance function accounting for the oscillator circuit, which is combined with the passive admittance of the coupled resonator. Very good correspondence has been obtained between simulation and measured results.This work was supported in part by the Spanish Ministry of Economy and Competitiveness and in part by the European Regional Development Fund (ERDF/FEDER) under Project TEC2017-88242-C3-1-R

Grant-free Radio Access IoT Networks: Scalability Analysis in Coexistence Scenarios

IoT networks with grant-free radio access, like SigFox and LoRa, offer low-cost durable communications over unlicensed band. These networks are becoming more and more popular due to the ever-increasing need for ultra durable, in terms of battery lifetime, IoT networks. Most studies evaluate the system performance assuming single radio access technology deployment. In this paper, we study the impact of coexisting competing radio access technologies on the system performance. Considering \mathpzc K technologies, defined by time and frequency activity factors, bandwidth, and power, which share a set of radio resources, we derive closed-form expressions for the successful transmission probability, expected battery lifetime, and experienced delay as a function of distance to the serving access point. Our analytical model, which is validated by simulation results, provides a tool to evaluate the coexistence scenarios and analyze how introduction of a new coexisting technology may degrade the system performance in terms of success probability and battery lifetime. We further investigate solutions in which this destructive effect could be compensated, e.g., by densifying the network to a certain extent and utilizing joint reception

Nonlinear dynamics of an oscillator inductively coupled to an external resonator for power transfer and data transmission

ABSTRACT: This work presents an investigation of the nonlinear dynamics of an oscillator that is inductively coupled to an external resonator for power transfer applications. Analytical expressions are derived for the oscillation frequency and output power, which provide insight into the effect of the coupled resonator on the oscillator solution. From the analytical study, criteria are derived to maximize the k range with a high efficiency and a limited variation of the oscillation frequency. The resistor of the external resonator can be modulated for data transmission to the core oscillator. Here the sensitivity to this resistor and its dependence on the coupling factor are analyzed in detail. The methods have been applied to a Class-E oscillator that has been analyzed through a contour-intersection technique. This is based on the extraction from harmonic balance (HB) of a bi-variate nonlinear admittance function accounting for the oscillator circuit, which is combined with the passive linear admittance function of the coupled resonator. The advantage is taken of the ease of this analysis to obtain constant-efficiency contours in the oscillatory regime, traced in the plane defined by the coupling factor and any suitable analysis parameter. By means of a bifurcation analysis, various phenomena, including the oscillation extinction plus onset versus the coupling factor and the appearance of quasi-periodic solutions, are detected and avoided. Very good correspondence has been obtained between simulation and measured results.This work was supported in part by the Spanish Ministry of Science and Innovation and in part by the European Regional Development Fund (MCIN/AEI10.13039/501100011033/ERDF “A Way of Making Europe”) under Grant TEC2017-88242-C3-1-R and Grant PID2020-116569RB-C31

A Self-Oscillating Approach for Wireless Power Transfer

We introduce a robust wireless power transfer scheme that theoretically works for any load and receiver position. We show that capacitive wireless power transfer systems with these new properties can be implemented by modifying simple operational Amplifier oscillator circuits. The load and the wireless power link are incorporated into the feedback of the oscillator. The operating frequency adopts to the best possible working condition when the load or receiver position change. We prove the concept by deriving a theoretical model and implementing the same experimentally. The experimentally measured frequency of operation and transferred power agrees well with our analytical solutions

A Fully-Integrated Quad-Band GSM/GPRS CMOS Power Amplifier

Concentric distributed active transformers (DAT) are used to implement a fully-integrated quad-band power amplifier (PA) in a standard 130 nm CMOS process. The DAT enables the power amplifier to integrate the input and output matching networks on the same silicon die. The PA integrates on-chip closed-loop power control and operates under supply voltages from 2.9 V to 5.5 V in a standard micro-lead-frame package. It shows no oscillations, degradation, or failures for over 2000 hours of operation with a supply of 6 V at 135° under a VSWR of 15:1 at all phase angles and has also been tested for more than 2 million device-hours (with ongoing reliability monitoring) without a single failure under nominal operation conditions. It produces up to +35 dBm of RF power with power-added efficiency of 51%