Distributed active transformer - a new power-combining andimpedance-transformation technique

In this paper, we compare the performance of the newly introduced distributed active transformer (DAT) structure to that of conventional on-chip impedance-transformations methods. Their fundamental power-efficiency limitations in the design of high-power fully integrated amplifiers in standard silicon process technologies are analyzed. The DAT is demonstrated to be an efficient impedance-transformation and power-combining method, which combines several low-voltage push-pull amplifiers in series by magnetic coupling. To demonstrate the validity of the new concept, a 2.4-GHz 1.9-W 2-V fully integrated power-amplifier achieving a power-added efficiency of 41% with 50-Ω input and output matching has been fabricated using 0.35-μm CMOS transistor

Fully integrated CMOS power amplifier design using the distributed active-transformer architecture

A novel on-chip impedance matching and power-combining method, the distributed active transformer is presented. It combines several low-voltage push-pull amplifiers efficiently with their outputs in series to produce a larger output power while maintaining a 50-Ω match. It also uses virtual ac grounds and magnetic couplings extensively to eliminate the need for any off-chip component, such as tuned bonding wires or external inductors. Furthermore, it desensitizes the operation of the amplifier to the inductance of bonding wires making the design more reproducible. To demonstrate the feasibility of this concept, a 2.4-GHz 2-W 2-V truly fully integrated power amplifier with 50-Ω input and output matching has been fabricated using 0.35-μm CMOS transistors. It achieves a power added efficiency (PAE) of 41 % at this power level. It can also produce 450 mW using a 1-V supply. Harmonic suppression is 64 dBc or better. This new topology makes possible a truly fully integrated watt-level gigahertz range low-voltage CMOS power amplifier for the first time

Virtual damping and Einstein relation in oscillators

This paper presents a new physical theory of oscillator phase noise. Built around the concept of phase diffusion, this work bridges the fundamental physics of noise and existing oscillator phase-noise theories. The virtual damping of an ensemble of oscillators is introduced as a measure of phase noise. The explanation of linewidth compression through virtual damping provides a unified view of resonators and oscillators. The direct correspondence between phase noise and the Einstein relation is demonstrated, which reveals the underlying physics of phase noise. The validity of the new approach is confirmed by consistent experimental agreement

Novel Approach to Design Ultra Wideband Microwave Amplifiers: Normalized Gain Function Method

In this work, we propose a novel approach called as “Normalized Gain Function (NGF) method” to design low/medium power single stage ultra wide band microwave amplifiers based on linear S parameters of the active device. Normalized Gain Function TNGF is defined as the ratio of T and |S21|^2, desired shape or frequency response of the gain function of the amplifier to be designed and the shape of the transistor forward gain function, respectively. Synthesis of input/output matching networks (IMN/OMN) of the amplifier requires mathematically generated target gain functions to be tracked in two different nonlinear optimization processes. In this manner, NGF not only facilitates a mathematical base to share the amplifier gain function into such two distinct target gain functions, but also allows their precise computation in terms of TNGF=T/|S21|^2 at the very beginning of the design. The particular amplifier presented as the design example operates over 800-5200 MHz to target GSM, UMTS, Wi-Fi and WiMAX applications. An SRFT (Simplified Real Frequency Technique) based design example supported by simulations in MWO (MicroWave Office from AWR Corporation) is given using a 1400mW pHEMT transistor, TGF2021-01 from TriQuint Semiconductor

Упрощенная модель тонкопленочного резонатора для применения в фильтрах высокого порядка

У роботі представлена розроблена авторами модель тонкоплівкового п'єзоелектричного резонатора з двома електродами, заснована на застосуванні багатоконтурних схем заміщення. Завдяки спрощеності структури, дана модель може бути легко інтегрована в більшість сучасних САПР і дозволить з високою точністю визначати вихідні характеристики резонатора у відносно широкому частотному діапазоні, що особливо важливо при моделюванні фільтрів високого порядку на базі резонаторів. Проведена верифікація моделі, що включає аналіз частотної залежності вхідного імпедансу у вузькому і широкому частотних діапазонах, а також дослідження узгодженості моделі при використанні різних матеріалів активного шару і електродів. Важливою перевагою запропонованої моделі є збільшення ефективності розрахунку та оптимізації складних схем із застосуванням великої кількості резонаторів за рахунок скорочення часу розрахунку.The simplified model of thin film piezoelectric resonator based on multiloop equivalent circuits was developed and presented in this work. The model allows the straightforward integration of the resonator’s electrical behavior into the most of modern CAD systems as a part of complex devices and enables the precise evaluation of the output characteristics in a relatively wide frequency range that is especially significant for the modelling of high-order filters composed of thin film bulk acoustic resonators. The model verification was given including: 1) the analysis of the absolute input impedance frequency dependence in wide and narrow frequency ranges; 2) the model agreement examination using different active layer and electrodes materials. An important advantage of proposed solution is the decreasing of calculation time and improving of optimization efficiency of complex RF circuits with a large number of resonators.В работе представлена разработанная авторами модель тонкопленочного пьезоэлектрического резонатора с двумя электродами, основанная на применении многоконтурных схем замещения. Благодаря упрощенности структуры, данная модель может быть легко интегрирована в большинство современных САПР и позволит с высокой точностью определять выходные характеристики резонатора в относительно широком частотном диапазоне, что особенно важно при моделировании фильтров высокого порядка на базе резонаторов. Проведена верификация модели, включающая анализ частотной зависимости входного импеданса в узком и широком частотных диапазонах, а также исследование согласованности модели при использовании различных материалов активного слоя и электродов. Важным преимуществом предложенной модели является увеличение эффективности расчета и оптимизации сложных схем с применением большого количества резонаторов за счет сокращения времени расчета

A Comparison between Class-E DC-DC Design Methodologies for Wireless Power Transfer

We consider the design of Wireless Power Transfer (WPT) systems based on inductive links and focus on recent works where the whole WPT system (i.e. both energy transmitter and energy receiver) is designed as an isolated resonant class-E DC-DC converter characterized by a loosely-coupled transformer. The aim of this work is to compare the classic WPT design approach with a novel one, which allows achieving the same performance with a significant reduction in the number of reactive components of the circuit, with beneficial effects in terms of system complexity, size, and cost. We will also show that such a reduction in the number of reactive components leads to improved performance robustness to variations in the inductive link coupling factor

A Unified Design Theory for Class-E Resonant DC–DC Converter Topologies

Resonant and quasi-resonant dc-dc converters have been introduced to increase the operating frequency of switching power converters, with advantages in terms of performance, cost, and/or size. In this paper, we focus on class-E resonant topologies, and we show that about twenty different architectures proposed in the last three decades can be reduced to two basic topologies, allowing the extension to all these resonant converters of an exact and straightforward design procedure that has been recently proposed. This represents an important breakthrough with respect to the state of the art, where class-E circuit analysis is always based on strong simplifying assumptions, and the final circuit design is achieved by means of numerical simulations. The potentialities of the proposed exact methodology are highlighted by realistic circuit-level simulations, where the desired waveforms are obtained in one single step without the need of a time-consuming iterative trial-and-error process

An Analytical Approach for the Design of Class-E Resonant DC-DC Converters

We present a new approach to design resonant dc-dc converters, that allows us to achieve both a more accurate implementation and a simpler architecture, by reducing the number of required passive components. The approach is applied to a class-E topology, and it is based on the analytic solution of the system of differential equations regulating the converter evolution. Our technique is also capable of taking into account the most important circuit nonidealities. This represents an important breakthrough with respect to the state of the art, where class-E circuit analysis is based on strong simplifying assumptions, and the final circuit design is achieved by means of numerical simulations after many time-consuming parametric sweeps. The developed methodology is dimensionless, and the achieved design curves can be denormalized to easily get the desired circuit design. Measurements on two different prototypes confirm an extremely high adherence to the developed mathematical approach.We present a new approach to design resonant dc-dc converters, that allows us to achieve both a more accurate implementation and a simpler architecture, by reducing the number of required passive components. The approach is applied to a class-E topology, and it is based on the analytic solution of the system of differential equations regulating the converter evolution. Our technique is also capable of taking into account the most important circuit nonidealities. This represents an important breakthrough with respect to the state of the art, where class-E circuit analysis is based on strong simplifying assumptions, and the final circuit design is achieved by means of numerical simulations after many time-consuming parametric sweeps. The developed methodology is dimensionless, and the achieved design curves can be denormalized to easily get the desired circuit design. Measurements on two different prototypes confirm an extremely high adherence to the developed mathematical approach