Multilevel inverter technology has emerged recently as a very important alternative in the area of high-power medium-voltage energy control. This paper presents the most important topologies like diode-clamped inverter (neutral-point clamped), capacitor-clamped (flying capacitor), and cascaded multicell with separate DC sources. Emerging topologies like asymmetric hybrid cells and soft-switched multilevel inverters are also discussed. This paper also presents the most relevant control and modulation methods developed for this family of converters: multilevel sinusoidal pulsewidth modulation, multilevel selective harmonic elimination, and space-vector modulation. Special attention is dedicated to the latest and more relevant applications of these converters such as laminators, conveyor belts, and unified power-flow controllers. The need of an active front end at the input side for those inverters supplying regenerative loads is also discussed, and the circuit topology options are also presented. Finally, the peripherally developing areas such as high-voltage high-power devices and optical sensors and other opportunities for future development are addressed.

Multilevel inverters: a survey of topologies, controls, and applications

Linear PA Design. Conventional High-Efficiency Amplifier Modes. Class AB PAs at GHz Frequencies. Practical Design of Class AB PAs. Overdrive and the Class F Mode. Switching Mode Amplifiers for RF Applications. Switching PA Modes at GHz Frequencies. Signals, Modulation Systems, and PA Nonlinearities. Efficiency Enhancement Techniques. Power Amplifier Bias Circuit Design. Power Amplifier Architecture. PA Linearization Techniques.

RF Power Amplifiers for Wireless Communications

The generation of RF/microwave power is required not only in wireless communications, but also in applications such as jamming, imaging, RF heating, and miniature dc/dc converters. Each application has its own unique requirements for frequency, bandwidth, load, power, efficiency, linearity, and cost. RF power is generated by a wide variety of techniques, implementations, and active devices. Power amplifiers are incorporated into transmitters in a similarly wide variety of architectures, including linear, Kalm, envelope tracking, outphasing, and Doherty. Linearity can be improved through techniques such as feedback, feedforward, and predistortion.

Power amplifiers and transmitters for RF and microwave

A control circuit of a surgical device is disclosed. The control circuit includes a first circuit portion coupled to at least one switch operable between an open state and a closed state. The first circuit portion communicates with a surgical generator over a conductor pair to receive a control signal to determine a state of the at least one switch.

Surgical generator for ultrasonic and electrosurgical devices

The class E tuned power amplifier consists of a load network and a single transistor that is operated as a switch at the carrier frequency of the output signal. The most simple type of load network consists of a capacitor shunting the transistor and a series-tuned output circuit, which may have a residual reactance. Circuit operation is determined by the transistor when it is on, and by the transient response of the load network when the transistor is off. The basic equations governing amplifier operation are derived using Fourier series techniques and a high- Q assumption. These equations are then used to determine component values for optimum operation at an efficiency of 100 percent. Other combinations of component values and duty cycles which result in 100-percent efficiency are also determined. The harmonic structure of the collector voltage waveform is analyzed and related amplifier configurations are discussed. While this analysis is directed toward the design of high-efficiency power amplifiers, it also provides insight into the operation of modern solid-state VHF-UHF tuned power amplifiers.

Idealized operation of the class E tuned power amplifier

A majority of people now have a digital mobile device whether it be a cell phone, laptop, or blackberry. Now that we have the mobility we want it to be more versatile and dependable; RF power amplifiers accomplish just that. These amplifiers take a small input and make it stronger and larger creating a wider area of use with a more robust signal.Switching mode RF amplifiers have been theoretically possible for decades, but were largely impractical because they distort analog signals until they are unrecognizable. However, distortion is not an issue with digital signals-like those used by WLANs and digital cell phones-and switching mode RF amplifiers have become a hot area of RF/wireless design. This book explores both the theory behind switching mode RF amplifiers and design techniques for them. *Provides essential design and implementation techniques for use in cma2000, WiMAX, and other digital mobile standards*Both authors have written several articles on the topic and are well known in the industry*Includes specific design equations to greatly simplify the design of switchmode amplifiers

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Switchmode RF power amplifiers

/pdf/rf-and-microwave-power-amplifier-and-transmitter-3qo4znas33.pdf

RF and Microwave Power Amplifier and Transmitter Technologies — Part 1

Combining solid theoretical discussions with practical design examples, this book is an essential reference on developing RF and microwave switchmode power amplifiers. With this book you will be able to: * Design high-efficiency RF and microwave power amplifiers on different types of bipolar and field-effect transistors using well-known and novel theoretical approaches, nonlinear simulation tools, and practical design techniques * Design any type of high-efficiency switchmode power amplifiers operating in Class D or E at lower frequencies and in Class E or F and their subclasses at microwave frequencies, with specified output power * Understand the theory and practical implementation of load-network design techniques based on lumped and transmission-line elements * Combine multi-stage Doherty architecture and switchmode power amplifiers to significantly increase efficiency of the entire radio transmitter * Learn the different types of predistortion linearization techniques required to improve the quality of signal transmission in a nonlinear amplifying system New to this edition: . Comprehensive overview of different Doherty architectures which are, and will be used in modern communication systems to save power consumption and reduce costs . A new chapter on analog and digital predistortion techniques . Coverage of broadband Class-F power amplifiers, high-power inverse Class-F power amplifiers for WCDMA systems, broadband Class-E techniques *Unique focus on switchmode RF and microwave power amplifiers that are widely used in cellular/wireless, satellite and radar communication systems and which offer major power consumption savings *Complete coverage of the new Doherty architecture which offers major efficiencies and savings on power consumption *Balances theory with practical implementatation, avoiding a cookbook approach, enabling engineers to develop better designs *Trusted content from leading figures in the field with a Foreword of endorsement by Zoya Popovic

Switchmode RF and Microwave Power Amplifiers

Class E power amplifiers achieve significantly higher efficiency than for conventional class B or C. Class E operates the transistor as an on/off switch and shapes the voltage and current waveforms to prevent simultaneous high voltage and high current in the transistor; that minimizes the power dissipation, especially during the switching transitions. In the published low-order class-E circuit, a transistor performs well at frequencies up to about 70% of its frequency of good class-B operation. An unpublished higher-order class E circuit operates well up to about double that frequency. The paper covers circuit operation, explicit design equations for the low-order class E circuit, optimization principles, and experimental results.

Class E high-efficiency power amplifiers, from HF to microwave

A nondissipative, resonant turn-off snubber eliminates the power dissipation of the traditional R-C-diode snubber, while providing protection against transistor breakdown from energy stored in the power-transformer leakage inductance. Four operating modes are analyzed. Complete design procedures are given, with experimental verification.

Nondissipative turn-off snubber alleviates switching power dissipation, second-breakdown stress and V CE overshoot: Analysis, design procedure and experimental verification

Nathan O. Sokal

Papers

Switchmode RF power amplifiers

RF and Microwave Power Amplifier and Transmitter Technologies — Part 1

Switchmode RF and Microwave Power Amplifiers

Class E high-efficiency power amplifiers, from HF to microwave

Nondissipative turn-off snubber alleviates switching power dissipation, second-breakdown stress and V CE overshoot: Analysis, design procedure and experimental verification