Lossless multi-way power combining and outphasing for radio frequency power amplifiers

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 102-106).For applications requiring the use of power amplifiers (PAs) operating at high frequencies and power levels, it is often preferable to construct multiple low power PAs and combine their output powers to form a high-power PA. Moreover, such PAs must often be able to provide dynamic control of their output power over a wide range, and maintain high efficiency across their operating range. This research work describes a new power combining and outphasing system that provides both high efficiency and dynamic output power control. The introduced system combines power from four or more PAs, and overcomes the loss and reactive loading problems of previous outphasing systems. It provides ideally lossless power combining, along with nearly-resistive loading of the individual power amplifiers over a very wide output power range. The theoretical fundamentals underlying the behavior and operation of this new combining system are thoroughly developed. Additionally, a straight-forward combiner design methodology is provided. The prototype design of a 27.12 MHz, four-way power combining and outphasing system is presented, implemented, and its performance is experimentally validated over a 1OW-1OOW (10:1) output power range.by Alexander S. Jurkov.S.M

Lossless Multiway Power Combining and Outphasing for High-Frequency Resonant Inverters

A lossless multi-way power combining and outphasing system have recently been proposed for high-frequency inverters and power amplifiers that offers major performance advantages over traditional approaches. This paper presents outphasing control strategies for the proposed power combining system that enable output power control through effective load modulation of the inverters. It describes a straightforward power combiner design methodology and enumerates various possible topological combiner implementations. Moreover, this study presents the first-ever experimental demonstration of the proposed outphasing system. The design of a 27.12 MHz, four-way power combining and outphasing system is described and used to experimentally verify the power combiner's characteristics. The proposed outphasing law is shown to be effective in controlling the output power over a 10-100 W (10:1) power range

Design of Single-Switch Inverters for Variable Resistance/Load Modulation Operation

Single-Switch inverters such as the conventional Class-E inverter are often highly load sensitive, and maintain zero-voltage switching over only a narrow range of load resistances. This paper introduces a design methodology that enables rapid synthesis of Class E and related single-switch inverters that maintain ZVS operation over a wide range of resistive loads. We treat the design of Class-E inverters for variable resistance operation and show how the proposed methodology relates to circuit transformations on traditional Class-E designs. We also illustrate the use of this transformation approach to realize Φ[subscript 2] inverters for variable-resistance operation. The proposed methodology is demonstrated and experimentally validated at 27.12 MHz in a Class E and Φ[subscript 2] inverter designs that operate efficiently over 12:1 load resistance range for an 8:1 and 10:1 variation in output power, respectively, and a 25-W peak output power.Massachusetts Institute of Technology. Center for Integrated Circuits and SystemsMIT Energy InitiativeSkolkovo Institute of Science and TechnologyWarsaw University of Science and Technology (Poland). Center for Advanced Studie

Techniques for efficient radio frequency power conversion

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019Cataloged from PDF version of thesis.Includes bibliographical references (pages 293-304).A diverse range of radio-frequency (RF) power applications demand RF power generation systems that allow for dynamic output power control while having the capability to efficiently deliver power into a varying load. While some of these existing and emerging applications are characterized with narrowband or single-frequency operation, others require operation over a range of frequencies. In such applications, the system architecture typically comprises an RF power amplifier (PA) or inverter along with a tunable impedance matching network (TMN). Electronically-controlled TMNs offer substantial benefits when it comes to the implementability of such highly reconfigurable and adaptive RF systems as they allow for proper impedance termination of the PA or inverter over the operating load and frequency range. This work explores the design of TMNs based on a solid-state technique that allows for faster and more accurate impedance matching compared to traditional approaches. The performance and design of such TMNs is demonstrated for plasma driving applications at 13.56 MHz. In addition, this work proposes techniques for designing switched-mode RF inverters that can operate efficiently over a wide load impedance range. These techniques are applied to the design of class E and class [Phi]2 inverter prototypes at 27.12 MHz, and their ability to handle large load modulation while maintaining high operating efficiency is demonstrated. The techniques presented in this work can be further applied to the integration of an RF power amplifier/inverter and a TMN into a single multi-transistor architecture capable of efficiently operating across frequency and load variation while providing dynamic output power control.by Alexander Jurkov.Ph. D.Ph.D. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Scienc

Tunable impedance matching networks based on phase-switched impedance modulation

The ability to provide accurate, rapid and dynamically-controlled impedance matching offers significant advantages to a wide range of present and emerging radio-frequency (RF) power applications. This work develops a new type of tunable impedance matching networks (TMN) that enables a combination of much faster and more accurate impedance matching than is available with conventional techniques. This implementation is based on a narrow-band technique, termed here phase-switched impedance modulation (PSIM), which entails the switching of passive elements at the RF operating frequency, effectively modulating their impedances. The proposed approach provides absorption of device parasitics and zero-voltage switching (ZVS) of the active devices, and we introduce control techniques that enable ZVS operation to be maintained across operating conditions. A prototype PSIM-based TMN is developed that provides a 50 Ohms match over a load impedance range suitable for inductively-coupled plasma processes. The prototype TMN operates at frequencies centered around 13.56 MHz at input RF power levels of up to 150 W

Tunable Matching Networks Based on Phase-Switched Impedance Modulation1

The ability to provide accurate, rapid, and dynamically controlled impedance matching offers significant advantages to a wide range of present and emerging radio-frequency (RF) power applications. This article develops a new type of tunable matching network (TMN) that enables a combination of much faster and more accurate impedance matching than is available with conventional techniques and is suitable for use at high power levels. This implementation is based on a narrow-band technique, termed here phase-switched impedance modulation (PSIM), which entails the switching of passive elements at the RF operating frequency, effectively modulating their impedances. The proposed approach provides absorption of device parasitics and zero-voltage switching (ZVS) of the active devices, and we introduce control techniques that enable ZVS operation to be maintained across operating conditions. A prototype PSIM-based TMN is developed that provides a 50-Ω match over a load impedance range suitable for inductively coupled plasma processes. The prototype TMN operates at frequencies centered around 13.56 MHz at input RF power levels of up to 200 W

Multi-Way Lossless Outphasing System Based on an All-Transmission-Line Combiner

A lossless power-combining network comprising cascaded transmission-line segments in a tree structure is introduced for a multi-way outphasing architecture. This architecture addresses the suboptimal loading conditions in Chireix outphasing transmitters while offering a compact and microwave-friendly implementation compared to previous techniques. In the proposed system, four saturated power amplifiers (PAs) interact through an all-TL power-combining network to produce nearly ideal resistive load modulation of the branch PAs over a 10:1 range of output powers. This work focuses on the operation of the combining network, deriving analytical expressions for input-port admittance characteristics and an outphasing control strategy to modulate output power while minimizing reactive loading of the saturated branch amplifiers. A methodology for combiner design is given, along with a combiner design example for compact layout. An experimental four-way outphasing amplifier system operating at 2.14 GHz demonstrates the technique with greater than 60% drain efficiency for an output power range of 6.2 dB. The system demonstrates a W-CDMA modulated signal with a 9.15-dB peak-to-average power ratio with 54.5% average modulated efficiency at 41.1-dBm average output power

Comparison of Radio-Frequency Power Architectures for Plasma Generation

Applications such as plasma generation require the generation and delivery of radio-frequency (rf) power into widely-varying loads while simultaneously demanding high accuracy and speed in controlling the output power across a wide range of power levels. Attaining high efficiency and performance across all operating conditions while meeting these system requirements is challenging, especially at high frequencies (10s of MHz) and power levels (1000s of Watts and above). This paper evaluates different architectures that directly address these challenges and enable efficient high-frequency operation over a wide range of output power levels and load impedances with the capability of fast output power control (e.g., within a few microseconds). We review techniques for achieving fast output power control and evaluate their suitability in efficient rf systems demanding accurate and fast control of output power. Two dc-to-rf system architectures utilizing the discussed power control techniques are presented to illustrate both the achievable performance benefits as well as their robustness to load impedance variation, and are compared using time-domain simulations. The results indicate the ability of the proposed architectures to maintain high efficiency (> 90%) across a very wide range of output power levels (e.g., over a factor of up to 85x) while being robust to load impedance variations